Court Opinion

ID: 9480666
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Date Created: 2023-08-05 07:54:53.261564+00
Date Added: 2024-06-11T17:47:49.774587
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Opinion for the Court PER CURIÁM.
Opinion dissenting in part filed by Chief Judge WALD.
Opinion concurring in part and dissenting in part filed by Circuit Judge SILBERMAN.
PER CURIAM:
Introduction
In November of 1986, a Lebanese newspaper reported that the United States had secretly sold weapons to Iran. Two months later, Congress established two committees charged with investigating the sales of arms to Iran, the diversion of proceeds therefrom to rebels (or “Contras”) fighting in Nicaragua, and the attempted cover-up of these activities (controversial events popularly known as “the Iran/Contra Affair”). In July of 1987, Lieutenant Colonel Oliver L. North, a former member of the National Security Council (“NSC”) staff, testified before the Iran/Contra congressional committees. North asserted his Fifth Amendment right not to testify before the committees, but the government compelled his testimony by a grant of use immunity pursuant to 18 U.S.C. § 6002. North testified for six days. His testimony was carried live on national television and radio, replayed on news shows, and analyzed in the public media.
Contemporaneously with the congressional investigation, and pursuant to the Independent Counsel statute, 28 U.S.C. §§ 591-599, the Special Division of this Court, see 28 U.S.C. § 49, appointed Lawrence E. Walsh as Independent Counsel (“IC”) and charged him with the investigation and prosecution of any criminal wrongdoing by government officials in the Iran/Contra events. As a result of the efforts of the IC, North was indicted and tried on twelve counts arising from his role in the Iran/Contra Affair. After extensive pretrial proceedings and a twelve-week trial, North was convicted in May of 1989 on three counts: aiding and abetting an endeavor to obstruct Congress in violation of 18 U.S.C. §§ 1505 and 2 (“Count 6”); destroying, altering, or removing official NSC documents in violation of 18 U.S.C. § 2071 (“Count 9”); and accepting an illegal gratuity, consisting of a security system for his *852home, in violation of 18 U.S.C. § 201(c)(1)(B) (“Count 10”). North now appeals his convictions on these counts.
Summary
Because of the length and complexity of our disposition of North’s appeal, we summarize our holdings.
(1) The District Court erred in failing to hold a full hearing as required by Kastigar v. United States, 406 U.S. 441, 92 S.Ct. 1653, 32 L.Ed.2d 212 (1972), to ensure that the IC made no use of North’s immunized congressional testimony. North’s convictions on all three counts are therefore vacated and remanded to the District Court for a Kastigar proceeding consistent with this opinion.
(2) The District Court’s jury instructions on Count 9 were erroneous in that they allowed the jury to convict without unanimously concluding that North committed any one of the criminal acts charged in Count 9. The instructions therefore violated United States v. Mangieri, 694 F.2d 1270 (D.C.Cir.1982). This error mandates reversal of North’s conviction on Count 9.
(3) The District Court did not err in refusing to instruct the jury on the defense of authorization purportedly recognized in United States v. Barker, 546 F.2d 940 (D.C.Cir.1976). The District Court did err, however, in limiting the jury’s consideration of authorization evidence as that evidence was relevant to the issue of intent in Count 9. North’s conviction on Count 9 is therefore reversed.
(4) The District Court did not err in quashing North’s subpoena of former President Reagan, and the quashal did not violate North’s Sixth Amendment rights.
(5) The District Court erred by instructing the jury that, as a matter of law, a congressional inquiry was “pending,” a necessary element of 18 U.S.C. § 1505 that must be found by the jury in order to convict. We conclude, however, that this error was harmless.
(6) Although the prosecution made highly improper remarks during closing argument, the District Court did not err in refusing to grant a new trial on that basis.
(7) The District Court’s rulings with regard to the Classified Information Procedures Act (“CIPA”) did not violate the Due Process Clause and were not otherwise erroneous.
(8) The credit given by the District Court to a juror’s denial of bias, even though the juror made false statements on the juror questionnaire, was not erroneous and in no way prevented North from exercising his peremptory challenges.
(9) The District Court did not err in declining to allow into evidence an edited videotape of the congressional testimony of Admiral John Poindexter, North’s former superior at the NSC.
(10) The District Court did not violate the Jury Selection and Service Act (“JSSA”).
(11) Although the District Court may have been better advised to use a different verdict form, the District Court did not improperly foreclose a general verdict of guilty or not guilty on Counts 6 and 9.
(12) Other than with respect to the element of intent in Count 9, the District Court committed no reversible error in its jury instructions concerning the critical elements of each offense.
(13) Venue in the District of Columbia was proper for Count 10.
(14) The District Court committed no error in allowing North to be tried as an aider and abettor on Count 6.
Therefore, North’s convictions on Counts 6, 9 and 10 are vacated and remanded for a Kastigar hearing. His conviction on Count 9 is reversed. Chief Judge Wald dissents from our holdings numbered (1) and (2). She also dissents from our holding numbered (3) insofar as we reverse North’s conviction on Count 9. Judge Silberman dissents from our holdings numbered (4), (5) and (7), and concurs dubitante in our holding number (6). He also dissents from our holding number (3) insofar as we do not reverse North’s conviction on Count 6.
*853I. Use of Immunized Testimony
A. Introduction
No person ... shall be compelled in any criminal case to be a witness against himself....
U.S. Const. Amend. V.
North argues that his Fifth Amendment right against self-incrimination was violated, asserting that the District Court failed to require the IC to establish independent sources for the testimony of witnesses before the grand jury and at trial and to demonstrate that witnesses did not in any way use North’s compelled testimony. North further argues that his Fifth Amendment right was violated by the District Court’s failure to determine whether or not the IC made “nonevidentiary” use of the immunized testimony.
North’s argument depends on the long-recognized principle that a predicate to liberal constitutional government is the freedom of a citizen from government compulsion to testify against himself:
And any compulsory discovery by extorting the party’s oath, or compelling the production of his private books and papers, to convict him of crime, or to forfeit his property, is contrary to the principles of free government. It is abhorrent to the instincts of an Englishman; it is abhorrent to the instincts of an American. It may suit the purposes of despotic power; but it cannot abide the pure atmosphere of political liberty and personal freedom.
Boyd v. United States, 116 U.S. 616, 631-32, 6 S.Ct. 524, 533, 29 L.Ed. 746 (1886). This rule has been established in England at least since 1641. See 8 Wigmore, Evidence § 2250 at 284 & n. 69 (McNaughton rev. ed. 1961); see also The Queen v. Coote, 4 L.R.-P.C. 599, 607 (1873) (“[T]he depositions on Oath of a Witness legally taken are evidence against him, should he be subsequently tried on a criminal charge, except so much of them as consist of answers to questions to which he has objected as tending to criminate him, but which he has been improperly compelled to answer.”).
Such compulsion is an ageless badge of tyranny, one that the framers and ratifiers of the Constitution were determined to avoid:
So deeply did the iniquities of the ancient system impress themselves upon the minds of the American colonists that the States, with one accord, made a denial of a right to question an accused person a part of their fundamental law, so that a maxim, which in England was a mere rule of evidence, became clothed in this country with the impregnability of a constitutional enactment.
Brown v. Walker, 161 U.S. 591, 597, 16 S.Ct. 644, 647, 40 L.Ed. 819 (1896).
Because the privilege against self-incrimination “reflects many of our fundamental values and most noble aspirations,” Murphy v. Waterfront Comm’n, 378 U.S. 52, 55, 84 S.Ct. 1594, 1596, 12 L.Ed.2d 678 (1964), and because it is “the essential mainstay of our adversary system,” the Constitution requires “that the government seeking to punish an individual produce the evidence against him by its own independent labors, rather than by the cruel, simple expedient of compelling it from his own mouth.” Miranda v. Arizona, 384 U.S. 436, 460, 86 S.Ct. 1602, 1620, 16 L.Ed.2d 694 (1966).
The prohibition against compelled testimony is not absolute, however. Under the rule of Kastigar v. United States, 406 U.S. 441, 92 S.Ct. 1653, 32 L.Ed.2d 212 (1972), a grant of use immunity under 18 U.S.C. § 60021 enables the government to *854compel a witness’s self-incriminating testimony. This is so because the statute prohibits the government both from using the immunized testimony itself and also from using any evidence derived directly or indirectly therefrom. Stated conversely, use immunity conferred under the statute is “coextensive with the scope of the privilege against self-incrimination, and therefore is sufficient to compel testimony over a claim of the privilege_ [Use immunity] prohibits the prosecutorial authorities from using the compelled testimony in any re-spect_” Kastigar, 406 U.S. at 453, 92 S.Ct. at 1661 (emphasis in original). See also Braswell v. United States, 487 U.S. 99, 108 S.Ct. 2284, 2295, 101 L.Ed.2d 98 (1988) (“Testimony obtained pursuant to a grant of statutory use immunity may be used neither directly nor derivatively.”).
When the government proceeds to prosecute a previously immunized witness, it has “the heavy burden of proving that all of the evidence it proposes to use was derived from legitimate independent sources.” Kastigar, 406 U.S. at 461-62, 92 S.Ct. at 1665. The Court characterized the government’s affirmative burden as “heavy.” Most courts following Kastigar have imposed a “preponderance of the evidence” evidentiary burden on the government. See White Collar Crime: Fifth Survey of Law-Immunity, 26 Am.Crim.L.Rev. 1169, 1179 & n. 62 (1989) (hereafter “Immunity’). The Court analogized the statutory restrictions on use immunity to restrictions on the use of coerced confessions, which are inadmissible as evidence but which do not prohibit prosecution. Kastigar, 406 U.S. at 461, 92 S.Ct. at 1665. The Court pointed out, however, that the “use immunity” defendant may “be in a stronger position at trial” than the “coerced confession” defendant because of the different allocations of burden of proof. Id.
A trial court must normally hold a hearing (a “Kastigar hearing”) for the purpose of allowing the government to demonstrate that it obtained all of the evidence it proposes to use from sources independent of the compelled testimony. See, e.g., United States v. Rinaldi, 808 F.2d 1579, 1584 (D.C.Cir.1987); United States v. Garrett, 797 F.2d 656, 663-65 (8th Cir.1986); United States v. Zielezinski, 740 F.2d 727, 733 (9th Cir.1984); United States v. Beery, 678 F.2d 856, 863 (10th Cir.1982). As this Court pointed out in United States v. De Diego, 511 F.2d 818, 823-24 (D.C.Cir.1975), a trial court may hold a Kastigar hearing pre-trial, post-trial, mid-trial (as evidence is offered), or it may employ some combination of these methods. A pre-trial hearing is the most common choice.
Whenever the hearing is held, the failure of the government to meet its burden can have most drastic consequences. One commentator has stated that “[i]f the tainted evidence was presented to the grand jury, the indictment will be dismissed; when tainted evidence is introduced at trial, the defendant is entitled to a new trial. [Defendants] are afforded similar protections against nonevidentiary uses of immunized testimony.” Immunity at 1179 (footnotes omitted).2
Dismissal of the indictment or vacation of the conviction is not necessary where the use is found to be harmless beyond a reasonable doubt. United States v. Serrano, 870 F.2d 1, 16 (1st Cir.1989); United States v. Byrd, 765 F.2d 1524, 1529 n. 8 (11th Cir.1985); United States v. Gregory, 730 F.2d 692, 698 (11th Cir.1984), cert. denied, 469 U.S. 1208, 105 S.Ct. 1170, 84 L.Ed.2d 321 (1985); Beery, 678 F.2d at 860 n. 3, 863; United States v. Shelton, 669 F.2d 446, 464 (7th Cir.), cert. denied, 456 U.S. 934, 102 S.Ct. 1989, 72 L.Ed.2d 454 (1982).
A district court holding a Kastigar hearing “must make specific findings on the independent nature of this proposed *855[allegedly tainted] evidence.” Rinaldi, 808 F.2d at 1584. Because the burden is upon the government, the appellate court “may not infer findings favorable to it on these questions.” Id. at 1583 (citing United States v. Hampton, 775 F.2d 1479, 1485-86 (11th Cir.1985)). A district court’s determination that the government has carried its burden of showing independent sources is a factual finding that is subject to review under the “clearly erroneous” standard. Serrano, 870 F.2d at 15; United States v. Garrett, 849 F.2d 1141, 1142 (8th Cir.1988); United States v. Brimberry, 803 F.2d 908, 917 (7th Cir.1986), cert. denied, 481 U.S. 1039, 107 S.Ct. 1977, 95 L.Ed.2d 817 (1987); United States v. Romano, 583 F.2d 1, 7 (1st Cir.1978).
B. District Court Proceedings
Before North’s trial, the District Court held a “preliminary” Kastigar inquiry, and issued an order based thereon which it subsequently adopted as final (with certain changes) without benefit of further proceedings or hearings. Compare United States v. Poindexter, 698 F.Supp. 300, 302 (D.D.C.1988) (hereafter “Kastigar Memo ”) (“[A]ny final consideration of the issue must be deferred until after a full trial.”) with United States v. North, No. 88-0080-02, 1989 WL 57487 (D.D.C. May 26, 1989) (order denying North’s motion to dismiss or for a Kastigar hearing) (“Defendant North’s post-trial Kastigar motion raises few new issues. It seeks in most instances to relitigate issues already resolved by the Court, presenting no new information that would justify changing the Court’s Memorandum Opinion and Order of June 16,1988 [the Kastigar Memo ] dealing with the full range of Kastigar problems_”).3
After reviewing the relevant factual and statutory background, the District Court made four findings concerning the government’s alleged use of immunized testimony before the grand jury. Kastigar Memo, 698 F.Supp. at 314-15. First, “[d]efen-dants’ immunized testimony was not submitted to the grand jury in any form.” Second, “[t]he grand jurors were effectively warned not to read about or look at or listen to this immunized testimony and it played no part in the grand jury’s unanimous decision to indict.” Third, “[t]he grand jury transcript and exhibits reflect solid proof and ample probable cause to indict on each and every count.” Fourth, “[n]one of the testimony or exhibits presented to the grand jury became known to the prosecuting attorneys on Independent Counsel’s staff or to him personally either from the immunized testimony itself or from leads derived from the testimony, directly or indirectly.” Id..
In reaching these conclusions, the District Court noted that the “Independent Counsel’s legitimate independent leads to every significant witness were carefully documented,” id. at 307-08; that the grand jury heard many witnesses before the immunity order issued, id. at 308; that North’s testimony was undertaken and concluded while the grand jury was in recess, id.; and that the “grand jurors were specifically, repeatedly and effectively instructed to avoid exposure to any immunized testimony.” Id. at 309. The District Court provided examples of various warnings given to grand jurors, id. at 309-11, and to grand jury witnesses. Id. at 311-12. The District Court also noted that Associate Independent Counsel were “apparently careful to avoid broad, rambling questions,” id. at 312, and that “written materials from Independent Counsel demonstrated] that all the prosecutor’s substantive witnesses were known to him before the first immunity grant.” Id. at 313.
Addressing what it referred to as nonevi-dentiary problems, the District Court noted that “[witnesses, probably a considerable number of them, have had their memories refreshed by the immunized testimony,” id., but because of its belief that “there is no way of determining, except possibly by a trial before the trial, whether or not any defendant was placed in a substantially worse position by the possible refreshment *856of a witness’ memory through such exposure,” id. at 314, the District Court concluded that “[i]f testimony remains truthful the refreshment itself is not an evidentiary use.” Id.
C. Analysis
North’s primary Kastigar complaint is that the District Court failed to require the IC to demonstrate an independent source for each item of evidence or testimony presented to the grand jury and the petit jury, and that the District Court erred in focusing almost wholly on the IC’s leads to witnesses, rather than on the content of the witnesses’ testimony. North also claims that the IC made an improper nonev-identiary use of the immunized testimony (as by employing it for purposes of trial strategy), or at least that the District Court failed to make a sufficient inquiry into the question. North also protests that his immunized testimony was improperly used to refresh the recollection of witnesses before the grand jury and at trial, that this refreshment caused them to alter their testimony, and that the District Court failed to give this question the careful examination it deserved. In our discussion here, we first consider alleged nonevidentiary use of immunized testimony by the IC. We will then proceed to consider the use of immunized testimony to refresh witnesses’ recollections. Finally, we will address the distinction between use of immunized testimony as a lead to procure witnesses and use insofar as it affects the substantive content of witnesses’ testimony.
Assuming without deciding that a prosecutor cannot make nonevidentiary use of immunized testimony, we conclude that the IC here did not do so and that the District Court’s inquiry and findings on this issue are not clearly erroneous. Thus, we do not decide the question of the permissibility or impermissibility of nonevidentiary use. However, contrary to the District Court, we conclude that the use of immunized testimony by witnesses to refresh their memories, or otherwise to focus their thoughts, organize their testimony, or alter their prior or contemporaneous statements, constitutes evidentiary use rather than non-evidentiary use. The District Court on remand is to hold the searching type of Kast-igar hearing described in detail below, concerning North’s allegations of refreshment. Finally, because the District Court apparently interpreted Kastigar as prohibiting the government only from using immunized testimony as a lead rather than using it at all, we hold that the District Court’s truncated Kastigar inquiry was insufficient to protect North’s Fifth Amendment right to avoid self-incrimination.
1. “Nonevidentiary” Use
The District Court briefly discussed the problem of nonevidentiary use of immunized testimony through witnesses and through the IC’s staff. Kastigar Memo, 698 F.Supp. at 313-14. The District Court found that witnesses had their memories refreshed with immunized testimony by “hearing the testimony, reading about it, being questioned about aspects of it before the Select Committees and, to some extent, by exposure to it in the course of responding to inquiries within their respective agencies.” Id. at 313. This exposure was not motivated, the Court found, by a desire “to harm a defendant or help the prosecution.” Id. The District Court concluded that in such a circumstance a “trial before the trial” was not necessary because “[n]o court has ever so required, nor did Kasti-gar suggest anything of the kind.” Id. at 314.
The District Court was similarly untroubled by allegations of prosecutorial exposure to immunized testimony through a grand juror or a witness: “Defendants in their zeal treat this as if even the tiniest exposure to a witness or grand juror constituted exposure to an incurable disease. Such is clearly not the case. Exposure to a fleeting snippet means nothing.” Id. As a matter of “common sense,” the District Court determined that a “prosecutor who inadvertently overhears mention of a fact already confirmed by his own independent investigation” cannot be said to have used immunized testimony; similarly, a defendant’s “Fifth Amendment rights are not infringed if a witness hears immunized tes*857timony yet testifies solely to facts personally known to the witness.” Id. The District Court concluded that “[t]he good faith of Independent Counsel cannot be questioned on this record.” Id.
This Circuit has never squarely addressed the question of whether or not Kastigar encompasses so-called noneviden-tiary use of immunized testimony. The federal use immunity statute does not speak in terms of “evidence,” but rather provides that “no testimony or other information compelled under the order (or any information directly or indirectly derived from such testimony or other information ) may be used against the witness in any criminal case_” 18 U.S.C. § 6002 (emphasis supplied). Kastigar does not define, except perhaps by implication, what nonevidentiary use of compelled testimony might be nor does it expressly discuss the permissible scope of such use.
As we suggested above, see note 2, supra, courts have differed on this question. Compare United States v. Semkiw, 712 F.2d 891 (3d Cir.1983); United States v. Pantone, 634 F.2d 716, 723 (3d Cir.1980); United States v. First W. State Bank, 491 F.2d 780, 787-88 (8th Cir.), cert. denied, 419 U.S. 825, 95 S.Ct. 42, 42 L.Ed.2d 49 (1974); United States v. McDaniel, 482 F.2d 305 (8th Cir.1973); United States v. Carpenter, 611 F.Supp. 768, 779 (N.D.Ga. 1985); United States v. Smith, 580 F.Supp. 1418, 1421-22 (D.N.J.1984); and United States v. Dornau, 359 F.Supp. 684, 687 (S.D.N.Y.1973), rev’d on other grounds, 491 F.2d 473 (2d Cir.1974) (all holding or strongly suggesting that Kastigar prohibits nonevidentiary use of compelled testimony) with United States v. Serrano, 870 F.2d 1, 16 (1st Cir.1989); United States v. Mariani, 851 F.2d 595, 600-01 (2d Cir.1988), cert. denied, — U.S.-, 109 S.Ct. 1654, 104 L.Ed.2d 168 (1989); United States v. Crowson, 828 F.2d 1427, 1431-32 (9th Cir.1987), cert. denied, 488 U.S. 831, 109 S.Ct. 87, 102 L.Ed.2d 63 (1988); and United States v. Byrd, 765 F.2d 1524, 1528-31 (11th Cir.1985) (all holding or observing that Kastigar does not prohibit nonevidentiary use of compelled testimony).
The two principal scholarly commentaries on the nonevidentiary use aspect of Kasti-gar also disagree. Compare Strachan, Self-Incrimination, Immunity, and Watergate, 56 Tex.L.Rev. 791, 820 (1978) (“[U]nless an immunized defendant is accorded a firm right to discovery and a comprehensive pretrial hearing on the issues of evidentiary and nonevidentiary use, the defendant is left totally dependent on the good faith of the prosecutors for the preservation of his constitutional rights— the result both the majority and dissent in Kastigar regarded as constitutionally unacceptable.”) with Humble, Nonevidentiary Use of Compelled Testimony: Beyond the Fifth Amendment, 66 Tex.L.Rev. 351, 355-56 (1987) (“[NJeither the immunity statute nor the fifth amendment requires the government to prove that it made no non-evidentiary uses of the defendant’s compelled testimony.”).
An initial difficulty is that a precise definition of the term nonevidentiary use is elusive. See, e.g., Humble, 66 Tex.L.Rev. at 353 (defining nonevidentiary uses as “uses that do not furnish a link in the chain of evidence against the defendant”); Stra-chan, 56 Tex.L.Rev. at 807 (Nonevidentiary use is “use of immunized disclosures that does not culminate directly or indirectly in the presentation of evidence against the immunized person in a subsequent criminal prosecution. This definition is too vague to be very helpful_”). Thus, we follow the lead of other courts and delineate nonevi-dentiary use by example rather than definition: “One court has described such nonev-identiary use as ‘conceivably includpng] assistance in focusing the investigation, deciding to initiate prosecution, refusing to plea bargain, interpreting evidence, planning cross-examination, and otherwise generally planning trial strategy.’ ” Serrano, 870 F.2d at 16 (quoting McDaniel, 482 F.2d at 311). Prosecutorial knowledge of the immunized testimony may help explicate evidence theretofore unintelligible, and it may expose as significant facts once thought irrelevant (or vice versa). Compelled testimony could indicate which witnesses to call, and in what order. Com*858pelled testimony may be helpful in developing opening and closing arguments. See Strachan, 56 Tex.L.Rev. at 806-10.
Kastigar itself did not expressly discuss the propriety of nonevidentiary use. The Court simply held that
immunity from use and derivative use is coextensive with the scope of the privilege against self-incrimination, and therefore is sufficient to compel testimony over a claim of the privilege. While a grant of immunity must afford protection commensurate with that afforded by the privilege, it need not be broader. Transactional immunity, which accords full immunity from prosecution for the offense to which the compelled testimony relates, affords the witness considerably broader protection than does the Fifth Amendment privilege.
Kastigar, 406 U.S. at 453, 92 S.Ct. at 1661. Thus, because “[i]mmunity from the use of compelled testimony, as well as evidence derived directly and indirectly therefrom” provides protection coextensive with the Fifth Amendment, the use immunity statute “prohibits the prosecutorial authorities from using the compelled testimony in any respect, and it therefore insures that the testimony cannot lead to the infliction of criminal penalties on the witness.” Id. (emphasis in original).
Responding to the contention that the use immunity statute provides scant protection from the various ways in which the government might use the compelled testimony, the Court pointed out that “[t]he statute provides a sweeping proscription of any use, direct or indirect, of the compelled testimony and any information derived therefrom_ This total prohibition on use provides a comprehensive safeguard, barring the use of compelled testimony as an ‘investigatory lead,’ and also barring the use of any evidence obtained by focusing investigation on a witness as a result of his compelled disclosures.” Kastigar, 406 U.S. at 460, 92 S.Ct. at 1665 (emphasis supplied). Section 6002 is constitutional, the Court concluded, because it “leaves the witness and the prosecutorial authorities in substantially the same position as if the witness had claimed the Fifth Amendment privilege.” Id. at 462, 92 S.Ct. at 1666.
Construing Kastigar in McDaniel, the Eighth Circuit forbade “all prosecutorial use of the testimony, not merely that which results in the presentation of evidence before the jury.” McDaniel, 482 F.2d at 311. Through a misunderstanding of North Dakota law, the United States Attorney read three transcript volumes of McDaniel’s immunized state grand jury testimony before he obtained the indictment from the federal grand jury. He did not know that McDaniel was immunized, so “he therefore could have perceived no reason to segregate McDaniel’s testimony from his other sources of information.” Id. Similarly, the court could not “escape the conclusion that the testimony could not be wholly obliterated from the prosecutor’s mind in his preparation and trial of the case.” Id. at 312. The court concluded that “if the immunity protection is to be coextensive with the Fifth Amendment privilege, as it must to be constitutionally sufficient, then it must forbid all prosecutorial use of the testimony, not merely that which results in the presentation of evidence before the jury.” Id. at 311. See also Semkiw, 712 F.2d at 895 (remanding for hearing as to prosecutor’s access to grand jury testimony and “what use she may have made of it in the preparation and conduct of the trial”); Pantone, 634 F.2d at 721 (finding that the government met its Kastigar burden partly because “a primary concern of Kastigar and the Department of Justice Guidelines, that mere access to immunized information may catalyze chains of investigation or subliminally affect decisions to prosecute, is not even in issue here”).
The McDaniel rule has been criticized or rejected by Serrano, 870 F.2d at 16, Mariani, 851 F.2d at 600-01, and Byrd, 765 F.2d at 1528-31. A judgment upon the nonevidentiary use issue was not necessary to the First Circuit’s holding in Serrano because the defendant had failed to raise the issue in the district court. However, the First Circuit disagreed with the McDaniel standard in dicta, stating that “[sjuch an approach amounts to a per se *859rule that would in effect grant a defendant transactional immunity once it is shown that government attorneys or investigators involved in the prosecution were exposed to the immunized testimony.” Serrano, 870 F.2d at 17 (emphasis in original). Because Kastigar expressly stated that a grant of immunity short of transactional immunity can still be constitutional if the grant is coextensive with the Fifth Amendment, the First Circuit “[did] not think this purpose is automatically frustrated by the government’s mere exposure to immunized testimony.” Id. The court concluded:
We also reject the notion that all nonevi-dentiary use necessarily violates the Fifth Amendment. While we need not decide whether certain nonevidentiary uses of immunized testimony may so prejudice the defendant as to warrant dismissal of the indictment, we agree with the Second Circuit that a prosecution is not foreclosed merely because the ‘immunized testimony might have tangentially influenced the prosecutor’s thought processes in preparing the indictment and preparing for trial.’
Id. at 17-18 (quoting Mariani, 851 F.2d at 600).
In Byrd, 765 F.2d at 1530-31, the Eleventh Circuit apparently agreed with the First and the Second:
So long as all the evidence presented to the grand jury is derived from legitimate sources independent of the defendant’s immunized testimony, and the grand jury finds that independent evidence sufficient to warrant the return of an indictment, the defendant’s privilege against self-incrimination has not been violat-ed_ [T]he privilege against self-incrimination is concerned with direct and indirect evidentiary uses of compelled testimony, and not with the exercise of prosecutorial discretion. If the contrary views of McDaniel and Semkiw were adopted, the realistic difference between transactional immunity and use immunity would become hopelessly blurred if not totally extinguished, thus negating the plain import of Kastigar....
The court then rejected as premature the defendant’s contention that the prosecutors had used his immunized testimony to make strategic decisions. Id. at 1531. We note that in a case following Byrd, the Eleventh Circuit continued to insist that Kastigar is concerned with evidentiary use only, but the court included as “evidentiary” certain “investigatory” uses that could reasonably be considered to be nonevidentiary. See United States v. Hampton, 775 F.2d 1479, 1490-91 & n. 53 (11th Cir.1985).
The IC favorably cites United States v. Schwimmer, 882 F.2d 22, 25 (2d Cir.1989), but it does not help him greatly on the nonevidentiary use point: “Section 6002 provides a ‘sweeping proscription’ of any direct or indirect use of the testimony, including its use as an investigatory lead, or as a means of focusing an investigation on the witness.” Id. (emphasis supplied). Indeed, in language which places in some doubt the Second Circuit’s apparent rejection in Mariani of the McDaniel approach, the Schwimmer opinion points out the danger of use that “might assist the prosecutor in focusing additional investigation, planning, cross-examination, or otherwise generally mapping a strategy for retrial,” id. at 26, and suggests that the prosecutors, in the event of. a retrial, should establish a Chinese wall.
The District Court in the present case distinguished McDaniel on the grounds that McDaniel turned on “unusual circumstances” (i.e., the prosecutor read the testimony and did not know that it was immunized). Kastigar Memo, 698 F.Supp. at 307 & n. 8. We are not so persuaded. The prosecutor’s knowledge (or lack thereof) that the testimony was immunized is relevant to the question of prosecutorial good faith, not prosecutorial use. The Fifth Amendment right of the defendant— which is, after all, Kastigar’s point and our concern — can be violated whether or not the prosecutor has knowledge that the testimony is immunized or that his witness has heard immunized testimony. Insofar as Serrano, Mariani, and Byrd may be read as establishing a rule that Kastigar allows nonevidentiary use of compelled tes*860timony under all circumstances, we find those cases troubling. We are not unsympathetic, nevertheless, to the concerns voiced by the First, Second and Eleventh Circuits and by the District Court here. In the present appeal, the record is extensive and the District Court’s findings are thorough as to precautions taken by the IC to prevent untoward exposure or use by his staff. The record is clear and the findings are not clearly erroneous. Without significant exposure, the IC could not have made significant nonevidentiary use, permissible or impermissible. Thus, even assuming without deciding that a prosecutor cannot make nonevidentiary use of immunized testimony, in the case before us the IC did not do so. We do not reach the precise question, therefore, of the permissible quantum of nonevidentiary use by prosecutors, or indeed whether such use is permissible at all. Our concern is the use of immunized testimony by witnesses before the grand jury and at trial.
We cannot agree with the District Court that the use of immunized testimony to refresh the memories of witnesses is a nonevidentiary matter and that therefore refreshment should not be subject to a Kastigar hearing because “[n]o court has ever so required, nor did Kastigar suggest anything of the kind.” Kastigar Memo, 698 F.Supp. at 314. In our view, the use of immunized testimony by witnesses to refresh their memories, or otherwise to focus their thoughts, organize their testimony, or alter their prior or contemporaneous statements, constitutes indirect evidentiary not nonevidentiary use. This observation also applies to witnesses who studied, reviewed, or were exposed to the immunized testimony in order to prepare themselves or others as witnesses.
Strictly speaking, the term direct eviden-tiary use may describe only attempts by the prosecutors to offer the immunized testimony directly to the grand jury or trial jury, as by offering the testimony as an exhibit. But the testimony of other witnesses is also evidence that is to be considered by the grand jury or the trial jury. When the government puts on witnesses who refresh, supplement, or modify that evidence with compelled testimony, the government uses that testimony to indict and convict. The fact that the government violates the Fifth Amendment in a circuitous or haphazard fashion is cold comfort to the citizen who has been forced to incriminate himself by threat of imprisonment for contempt. The stern language of Kastigar does not become lenient because the compelled testimony is used to form and alter evidence in oblique ways exclusively, or at a slight distance from the chair of the immunized witness. Such a looming constitutional infirmity cannot be dismissed as merely nonevidentiary. This type of use by witnesses is not only evidentiary in any meaningful sense of the term; it is at the core of the criminal proceeding.
In summary, the use of immunized testimony — before the grand jury or at trial — to augment or refresh recollection is an evi-dentiary use and must be dealt with as such.
2. Refreshment
Both the trial and the grand jury proceedings involved “a considerable number” of witnesses who had “their memories refreshed by the immunized testimony,” Kastigar Memo, 698 F.Supp. at 313, a use of compelled testimony that the District Court treated as nonevidentiary. Id. The District Court stated that “[tjhere is no way a trier of fact can determine whether the memories of these witnesses would be substantially different if it had not been stimulated by a bit of the immunized testimony itself” and that “there is no way of determining, except possibly by a trial before the trial, whether or not any defendant was placed in a substantially worse position by the possible refreshment of a witness’ memory through such exposure.” Id. at 314. The District Court found that such taint occurs in the “natural course of events” because “[mjemory is a mysterious thing that can be stirred by a shaggy dog or a broken promise.” Id. at 313.
This observation, while likely true, is not dispositive of the searching inquiry Kastigar requires. The fact that a *861sizable number of grand jury witnesses, trial witnesses, and their aides apparently immersed themselves in North’s immunized testimony leads us to doubt whether what is in question here is simply “stimulation” of memory by “a bit” of compelled testimony. Whether the government’s use of compelled testimony occurs in the natural course of events or results from an unprecedented aberration is irrelevant to a citizen’s Fifth Amendment right. Kastigar does not prohibit simply “a whole lot of use,” or “excessive use,” or “primary use” of compelled testimony. It prohibits “any use,” direct or indirect. From a prosecutor’s standpoint, an unhappy byproduct of the Fifth Amendment is that Kastigar may very well require a trial within a trial (or a trial before, during, or after the trial) if such a proceeding is necessary for the court to determine whether or not the government has in any fashion used compelled testimony to indict or convict a defendant.
We readily understand how court and counsel might sigh prior to such an undertaking. Such a Kastigar proceeding could consume substantial amounts of time, personnel, and money, only to lead to the conclusion that a defendant — perhaps a guilty defendant — cannot be prosecuted. Yet the very purpose of the Fifth Amendment under these circumstances is to prevent the prosecutor from transmogrifying into the inquisitor, complete with that officer’s most pernicious tool — the power of the state to force a person to incriminate himself. As between the clear constitutional command and the convenience of the government, our duty is to enforce the former and discount the latter.
The District Court ruled that “[i]f testimony remains truthful the refreshment itself is not an evidentiary use.” Id. at 314. But Kastigar addresses “use,” not “truth.” If the government uses immunized testimony to refresh the recollection of a witness (or to sharpen his memory or focus his thought) when the witness testifies before a grand jury considering the indictment of a citizen for acts as to which the citizen was forced to testify, then the government clearly has used the immunized testimony. Even if “truthfulness” were the focus of the Kastigar inquiry, the present record does not.disclose the basis for the determination that the testimony of any witness was “truthful,” nor does it indicate how we might review such a determination.
The IC attempts to meet North’s refreshment argument by relying on United States v. Apfelbaum, 445 U.S. 115, 124-27, 100 S.Ct. 948, 953-55, 63 L.Ed.2d 250 (1980), for the proposition that Kastigar “prohibits use [of immunized testimony] by the prosecution, not by others.” Brief for Appellee at 24. The IC misreads Apfel-baum, which is concerned with how immunized testimony may or may not be used rather than with who may or may not use it. In Apfelbaum, the Supreme Court stated that it had never held that the Fifth Amendment precludes all use of immunized testimony because “[s]uch a requirement would be inconsistent with the principle that the privilege does not extend to consequences of a noncriminal nature, such as threats of liability in civil suits, disgrace in the community, or loss of employment.” Apfelbaum, 445 U.S. at 125, 100 S.Ct. at 954 (emphasis supplied). North does not contend that the government violated his Fifth Amendment right because he received bad press as a result of his immunized testimony, or that he has been unable to find employment. Rather, he protests that the government used his immunized testimony to secure his indictment and subsequent conviction as a federal felon. Because North appeals a judgment that apparently violates his Fifth Amendment privilege by the imposition of criminal sanctions, we find Apfelbaum inapplicable to this case.
The IC further relies on Monroe v. United States, 234 F.2d 49, 56-57 (D.C.Cir.), cert. denied, 352 U.S. 873, 77 S.Ct. 94, 1 L.Ed.2d 76 (1956), for the proposition that recollection may be refreshed with inadmissible evidence even when the government violated the Fourth and Fifth Amendments to obtain the evidence. In Monroe, this Court allowed an undercover police officer *862to refresh his recollection with recordings of conversations between himself and the defendants. The recordings were not in evidence. The refreshment was permissible because, inasmuch as the conversations were his own, the “connection between any possible violation of the statute [section 605 of the Federal Communications Act, 47 U.S.C. § 605] and his testimony had ‘become so attenuated as to dissipate the taint’ in its relation to admissibility.” Monroe, 234 F.2d at 57 (quoting Nardone v. United States, 308 U.S. 338, 341, 60 S.Ct. 266, 267 84 L.Ed. 307 (1939)). Thus, the officer’s “testimony was not itself the product of an illegal interception; he repeated on the stand what he himself had heard.” Id. The IC analogizes the officer in Monroe to the witnesses here, claiming that “the testimony of witnesses about matters they had personally heard or observed is the product of their own memory, not of immunized testimony they might have seen or read.” Brief for Appellee at 25.
We cannot agree. As an initial matter, Monroe nowhere hints that a violation of the Fourth or Fifth Amendments was at issue. In Monroe, this Court concluded that refreshed testimony was not “publication” within the meaning of section 605 of the Federal Communications Act. Here, what the federal use immunity statute prohibits is “use” of the immunized testimony. The IC would have us adopt a parallel rule: as refreshment was not “publication,” so now refreshment is not “use.” But, the immunity statute is constitutional only because it is coextensive with the Fifth Amendment. The clear language of the Constitution, coupled with the Supreme Court’s sweeping approach in Kastigar, requires us to define “use” more broadly than we defined “publication” for purposes of the Federal Communications Act and prevents the sort of parallelism that the IC urges upon us. Because we conclude that refreshment is “use” within the meaning of Kastigar and the statute, the Monroe rule is inapplicable.
Indeed, the fact that immunized testimony has entered the consciousness of someone other than the immunized witness does not lessen the heavy burden upon the government to show that it has made no use, directly or indirectly, of the compelled testimony. The following hypothetical illustrates the weakness of the IC’s argument. A prosecutor locates a witness known to have observed certain events, seemingly inconsequential at the time but later critical to a criminal prosecution. The witness has absolutely no recollection of those events. The prosecution then arranges to procure the immunized testimony of the defendant. The forgetful witness sits in the gallery and listens to that immunized testimony. Under the IC’s theory, that witness could then be brought forward to relate the events he had previously forgotten. It would require a curiously strained use of language and learning to hold that in such a case no “use” of the immunized testimony had been made against the defendant.
The IC offers no logical distinction between that hypothetical and the dangers of use in the case at bar. It may be that it is possible in the present case to separate the wheat of the witnesses’ unspoiled memory from the chaff of North’s immunized testimony, but it may not. There at least should be a Kastigar hearing and specific findings on that question. If it proves impossible to make such a separation, then it may well be the case that the prosecution cannot proceed. Certainly this danger is a real one in a case such as this where the immunized testimony is so broadly disseminated that interested parties study it and even casual observers have some notion of its content. Nevertheless, the Fifth Amendment requires that the government establish priorities before making the immunization decision. The government must occasionally decide which it values more: immunization (perhaps to discharge institutional duties, such as congressional fact-finding and information-dissemination) or prosecution. If the government chooses immunization, then it must understand that the Fifth Amendment and Kastigar mean that it is taking a great chance that the witness cannot constitutionally be indicted or prosecuted.
*863Even before the congressional Iran/Contra committees began taking testimony, the IC recognized this problem in his memorandum to the committees concerning use immunity: “[A]ny grant of use and derivative use immunity would create serious— and perhaps insurmountable — barriers to the prosecution of the immunized witness.” Memorandum of the Independent Counsel Concerning Use Immunity 1 (Jan. 13, 1987) (Submitted to the Joint Congressional Iran/Contra Committees) (JA at 2502). See also id. at 4 (JA at 2505) (“Indeed, the prosecutor must demonstrate that all its evidence is based on entirely legitimate sources, independent of the compelled testimony. ... [SJince Kastigar, most lower courts have held that Section 6002 prohibits both evidentiary and nonevidentiary use of compelled testimony.”) (emphasis in original); id. at 5 (JA at 2506) (“Under these principles, the prosecution must not only prove that all of its evidence was derived from sources independent of the immunized testimony, but also demonstrate that no nonevidentiary or strategic use was made of the immunized testimony or the fruits of the testimony. In practice, these burdens are often very difficult to satisfy.”); id. at 6 (JA at 2507) (“ ‘[UJnder the circumstances of many cases, use of the statute will effectively preclude a future prosecution of the witness for the matters to which his/her testimony related.' ”) (citing United States Attorneys’ Manual at 1-11.212) (emphasis supplied in IC’s memorandum). These observations have indeed proven prescient, and we commend them to the District Court upon remand.
3. “Identity of Witness” vs. “Content of Testimony”
The refreshment of witnesses’ recollections is indicative, but not exhaustive, of the Kastigar questions left unanswered on the present record. The District Court’s disposition of the “identity-of-witness” issue, see supra at 855-56, does not dispose of the “content-of-testimony” Kastigar problem: the District Court inquired as to whether the names of witnesses were derived independently of the immunized testimony, but it made no determination of the extent to which the substantive content of the witnesses’ testimony may have been shaped, altered, or affected by the immunized testimony.
A central problem in this case is that many grand jury and trial witnesses were thoroughly soaked in North’s immunized testimony, but no effort was made to determine what effect, if any, this extensive exposure had on their testimony. Papers filed under seal indicate that officials and attorneys from the Department of Justice, the Central Intelligence Agency, the White House, and the Department of State gathered, studied, and summarized North’s immunized testimony in order to prepare themselves or their superiors and colleagues for their testimony before the investigating committees and the grand jury. JA at 3365-92 (classified appendix). A few examples will suffice.
A senior Department of Justice official, identified as “Witness No. 1” in North’s ex parte appendix filed under seal with the District Court, watched North’s testimony on a television located in his office, read media reports of the immunized testimony, and received transcribed portions of that testimony. This senior official watched the testimony because he headed a Department of Justice team charged with preparing the Attorney General for his testimony before the committees and the grand jury. Subsequent to his study of the immunized testimony, this official testified before the grand jury in late January or early February of 1988. Defendant’s Ex Parte Designation of Witnesses Pursuant to Court Order 1-2 (Apr. 21, 1988) (JA at 3240-41).
Another senior Justice Department official, identified as “Witness No. 4,” also saw the immunized testimony and gathered reports (particularly in two areas) in his capacity as a member of the team headed by Witness No. 1. Id. at 4 (JA at 3243). Indeed, the Attorney General testified before the grand jury seven times after having been exposed to the immunized testimony directly and indirectly through this “prep team.” A Department of Justice official (“Witness No. 5”) was assigned to help the IC obtain evidence from overseas sources. *864Witness No. 5 was exposed to immunized testimony through the public media and through in-house Department of Justice publications that reported on the immunized testimony. Id. at 4-5 (JA at 3243-44). Another member of the Justice Department’s prep team for the Attorney General (“Witness No. 6”) was similarly exposed to the testimony, id. at 5 (JA at 3244), as was a colleague on the team (“Witness No. 7”) who subsequently testified before the grand jury in December of 1987. Id. at 6 (JA at 3245). Another senior Department of Justice official (“Witness No. 8”) watched much of the testimony on the television in his office, watched media analyses of the testimony, was part of the prep team, and testified before the grand jury in January of 1988. Id.
Nor were all of the apparently tainted witnesses from the Department of Justice. Three CIA attorneys and one CIA official were exposed to North’s immunized testimony. One CIA attorney (“Witness No. 10”) watched most of North’s testimony, videotaped it, and obtained transcripts of the testimony, transcripts which he subsequently annotated. He also read press accounts of the testimony and was part of a CIA prep team charged with helping CIA employees ready themselves for their testimony before Congress and the grand jury. Witness No. 10 had interviews with the Office of Independent Counsel and allegedly used knowledge gleaned from the immunized testimony in discharging his duty as counsel to CIA employees who subsequently testified. Id. at 7-8. (JA at 3246-47). Another CIA attorney (“Witness No. 11”) was apparently part of a CIA task force on the Iran/Contra affair. Her function and the degree of her exposure approximated that of Witness No. 10. Id. at 8-9 (JA at 3247-48). The CIA official (“Witness No. 12”) apparently suffered extensive exposure to media reports of the testimony. Although he did not testify to the grand jury or at trial, he was interviewed by the IC after his exposure. Id. at 9-10 (JA at 3248-49).
Furthermore, two White House officials (“Witnesses Nos. 13 and 15”) were exposed by watching the testimony and reading about it in newspapers and magazines. Witness No. 13 did not testify to the grand jury after his exposure, but did testify at trial. After his exposure, he met with the IC in February of 1988 and provided him with factual information. Witness No. 15 was similarly exposed, and testified before the grand jury in February of 1988. Id. at 10-11 (JA at 3249-50).
The testimony of Robert C. McFarlane, the National Security Advisor to President Reagan, is especially troubling and is indeed emblematic of both the weakness of the IC’s position and the necessity of further Kastigar inquiry. Although McFar-lane completed his grand jury testimony before North gave his immunized testimony, McFarlane was a key government witness at trial. He testified before the investigating committees prior to North’s immunized testimony, but then specifically requested and was granted a second appearance after North testified in order to respond to North’s testimony. See Senate Select Comm, on Secret Military Assistance to Iran and the Nicaraguan Opposition & House Select Comm, to Investigate Covert Arms Transactions with Iran, Report of the Congressional Comm. Investigating the Iran/Contra Affair, with Supplemental, Minority and Additional Views, S.Rep. No. 216, H.R.Rep. No. 433, 100th Cong., 1st Sess. 687 (1987). In his second appearance on Capitol Hill, McFarlane revised his earlier testimony in light of North’s testimony, and directly responded to North’s testimony at certain points. See, e.g., id. at 40, 41, 399 and accompanying notes. He also apparently managed to recall items that he had not remembered in his prior testimony. McFarlane subsequently testified at North’s trial. Trial Transcript at 3916 et seq. (JA at 1041 et seq.). No effort was made to determine what use — if any — this government witness made of North’s testimony in his trial testimony.
Our dissenting colleague chastises us for use of the passive voice when we state that “many grand jury and trial witnesses were thoroughly soaked in North’s immunized testimony....” See supra at 863; Wald Dissent at 920 n. 7. As a general proposi*865tion, we agree that the virtues of the active voice are irrefutable. See W. Strunk, Jr. & E.B. White, The Elements of Style 18 (3d ed. 1979). Our colleague goes further, however. The dissent concludes that all of these witnesses, familiar with Kastigar, “soaked themselves in the immunized testimony” and that “it goes beyond reason to insist that the IC must additionally demonstrate that Justice Department officials from the same Administration as North himself did not purposefully use North’s immunized testimony in preparing for their own or their colleagues’ grand jury appear-ances_” Wald Dissent at 920 n. 7 (emphasis in original).
As an initial matter, there is absolutely nothing in the voluminous record that would even begin to support the conspiracy theory that the dissent advocates. In this heavily lawyered and professionally argued appeal, this notion appeared neither in the briefs nor at oral argument. Even when presented with colorable evidence, conspiracy theories are often difficult to believe, if only because the claims made for them are simultaneously grandiose and improbable. Such a theory presented without any evidence at all, indeed, without any allegations, is even less persuasive.
The more important point, however, is that such a conspiracy — even if it existed — would be entirely irrelevant to the issue before us, which is whether or not North’s Fifth Amendment right was violated. The Department of Justice could have held evening classes in “The Parsing and Deconstruction of Kastigar” for the very purpose of “derailing” the IC’s prosecution, and such a curriculum would have been simply irrelevant to the question of whether or not the prosecution’s case made use of North’s compelled testimony. As the District Court aptly observed, we do not countenance political trials in this country, and this matter is not styled Independent Counsel v. Executive Branch, or even Congress v. Executive Branch. Rather, this is an individual’s appeal from his criminal conviction, an appeal based on his contention that the government has violated his fundamental, enumerated constitutional right not to incriminate himself. We must so treat it.
The IC relies on Patton v. Yount, 467 U.S. 1025, 1035, 104 S.Ct. 2885, 2891, 81 L.Ed.2d 847 (1984), for the proposition that exposed jurors need not be disqualified (even if they have formed an opinion as to guilt) if they can put their opinions aside and make a judgment on the record. The IC’s reliance on Patton is ill-placed. Patton is a Sixth Amendment case that is concerned with impartial jurors, not immunized testimony. North’s Kastigar argument does not depend on the partiality of jurors. Rather, he protests that the government used his compelled testimony against him. Patton simply does not speak to the question before us.
The core purpose of the immunity statute, 18 U.S.C. §§ 6001-6005, is to allow the prosecution of an immunized witness while preventing use of his compelled testimony. One forbidden use of the immunized testimony is the identification of a witness, but other uses of a citizen’s immunized testimony — as by presenting the testimony of grand jury or trial witnesses that has been derived from or influenced by the immunized testimony — are equally forbidden. As we said in United States v. De Diego, 511 F.2d 818, 821 (D.C.Cir.1975), it is clear “that ‘[o]nce immunity is shown, the prosecutor has the burden of demonstrating that its use of the immunized testimony has not tainted any aspect of the case up to indictment and will not do so during trial.’ ” (emphasis supplied). In De Diego, the trial court had dismissed the indictment against a burglar involved in the break-in of a psychiatrist’s office. The district court dismissed the indictment on the grounds that the Special Prosecutor (the predecessor of the Independent Counsel) had not met his burden of establishing that De Diego’s testimony, compelled pursuant to the immunity granted by the State of Florida, would not taint the case. This Court reversed because the district court “had no discretion to dismiss the case without giving the Government an opportunity to prove lack of taint.” De Diego, 511 F.2d at 822. We also noted that the government had independent, legitimate evidence as to De Die*866go’s involvement in the break-in. Id. at 824. In the face of North’s Kastigar protest, the case before us presents the opposite danger: requiring no demonstration of independent sources for the evidence presented to the grand jury.
The District Court relied on United States v. Rinaldi, 808 F.2d 1579, 1583-84 (D.C.Cir.1987) (per curiam), for its conclusion that the IC’s independent discovery of witnesses was dispositive of the invalidity of North’s Kastigar claim. Kastigar Memo, 698 F.Supp. at 313 n. 15. We read Rinaldi otherwise.
In Rinaldi, the defendant pled guilty to a count of conspiracy to import heroin. He appealed the district court’s denial of his motion to suppress certain testimony that he alleged was known to the government only through his immunized testimony. A codefendant who had been present during some of Rinaldi’s immunized testimony later testified to the grand jury. Her grand jury testimony was elicited in part by leading questions from the government attorney. The government argued that the co-defendant knew all the important details, that the government had developed her as a witness independently of the immunized testimony, and that its discovery of her testimony was inevitable, but the trial court made no specific findings to that effect on the record before it. The government had provided no independent basis for the leading questions. This Court therefore remanded for further evidentiary hearings and specific findings.
In Rinaldi we pointed out that “[a]s the government bore the burden of proving that Reardon’s testimony was free of taint and independently derived, we may not infer findings favorable to it on these questions.” Rinaldi, 808 F.2d at 1583 (emphasis supplied) (citing United States v. Hampton, 775 F.2d 1479, 1485-86 (11th Cir.1985)). The emphasized portion of this statement directs us to two inquiries: the taint of the testimony and the derivation of the testimony. The District Court in the present case concentrated only on the independence of the leads to witnesses, rather than on the substance of their testimony. Kastigar Memo, 698 F.Supp. at 313 (“[A]ll the prosecutor’s substantive witnesses were known to him before the first immunity grant.”); id. at 312 (“[T]he immunized testimony taken before the Select Congressional Committees was elicited relatively late and well after the apparent diversion of funds, various cover-up tactics and many other facts relevant and material to the charges in this indictment were known to Independent Counsel.”); id. at 308 (“Nearly 950 pages of transcript [of the IC’s interrogation of Secord] cover interviews occurring before either North or Poindexter were compelled to testify publicly.”). Although a methodology based on derivation is a sound starting point for a Kastigar inquiry, such an approach is incomplete. On the record, it is clear that the District Court focused solely on the derivation of the witnesses’ testimony while dealing with that testimony’s substantive content only by invoking other devices, such as the IC’s “warnings” to grand jury witnesses.
Our dissenting colleague would avoid the entire foregoing analysis by equating the District Court’s “finding” that North’s immunized testimony was not presented to the grand jury with a “finding” that the testimony was not used at trial, an equation allegedly supported by the District Court’s remark that North’s post-trial Kastigar motion “presented no new information” that would warrant an additional hearing. Concluding that these are factual findings, the dissent indicates that we may not reverse them unless they are clearly erroneous. See Wald Dissent at 916, 921-923.
We disagree. In addition to the fact that the District Court did not actually make a specific finding that North’s immunized testimony was not used at trial, we note that the District . Court also “found” that grand jury witnesses had their memories refreshed by immunized testimony, but held that this use of the immunized testimony posed no Kastigar difficulty as long as the witnesses’ testimony was truthful. As we have already discussed, see supra at 860-863, such a use of immunized testimony is impermissible, *867and the resulting truth or falsity of the witnesses’ testimony is irrelevant to the issue before us. Thus, our colleague cannot logically proceed from a “finding” concerning the grand jury to a “finding” concerning the trial because the former is the product of straightforward legal error not subject to clearly erroneous review. Simply put, a reviewing court cannot always accept as a “factual finding” any conclusion so labeled by a district court; rather, the appellate court must be aware of what the district court believed to be the object of its search. If the lamp by which the District Court here searched was legally erroneous, then even an encyclopedia of facts boots it little. Indeed, as the dissent implicitly concedes, see Wald Dissent at 915, the District Court did not even claim to examine the grand jury transcripts for the presence of immunized testimony in the substance of witnesses’ testimony.
Because of the legal infirmity of the District Court’s grand jury finding, we decline to place great weight on the assertion that North’s post-trial Kastigar motion presented “no new information.” We are particularly mystified by our colleague’s statement that “[i]n determining that the trial testimony presented ‘no new information’ vis-a-vis the grand jury testimony, Judge Gesell obviously compared the substance of McFarlane’s presentations before the grand jury and at trial.” Wald Dissent at 923. To the contrary, the District Court’s “no new information” statement in no way suggests that there was a comparison between McFarlane’s grand jury testimony and his trial testimony. Given the witness’s 180-degree public about-face before Congress, we doubt that the two sets of testimony were the same. At the very least, we are unprepared to hold that they were the same without a hearing on the question or to state that the District Court made such a finding when in fact it did not.
Our dissenting colleague asserts that she examined the grand jury transcripts, determined which witnesses testified as to matters touching upon Counts 6, 9 and 10, and then compared the substance of those witnesses’ testimony both with their prior statements to the FBI and with North’s trial testimony. Although we do not doubt our colleague’s thoroughness and perseverance, her review cannot substitute for the hearing required under Kastigar for at least three reasons. First, the dissent does not determine that trial witnesses in no way incorporated, used or relied upon North’s testimony in giving their own; rather, it relies on the District Court’s legally erroneous finding concerning grand jury testimony, an approach that is flawed for the reasons noted above. Second, even by the dissent’s lights, two Justice Department officials were substantially exposed to North’s testimony and subsequently testified before the grand jury on matters concerning Count 6. See Wald Dissent at 919-920. Even if we were to accept the dissent’s conclusion that one of those witnesses testified consistently with a prior FBI interview, see id. at 919, we are still left with the other witness. Under Rinal-di, the presence of the remaining witness requires a remand, unless the “pragmatic” approach that the dissent apparently thinks we endorsed in that case, see Wald Dissent at 914, is correct and Kastigar has virtually no substance. Finally, and most importantly, an ex parte review in appellate chambers is not the equivalent of the open adversary hearing contemplated by Kasti-gar. See United States v. Zielezinski, 740 F.2d 727, 734 (9th Cir.1984); see also Section (D), infra.
The primary teaching of Rinaldi is not pragmatism, but that the government always bears the burden of proof and that we may not infer findings favorable to the government. The dissent simply shifts the burden of proof to North, apparently heedless of Kastigar and Rinaldi. The dissent repeats this somewhat fundamental error in its discussion of witness refreshment, see Wald Dissent at 920-22; in its inference of findings that the District Court did not make concerning the substance of grand jury testimony; in its discussion of grand juror exposure, see id. at 921-22; and, tellingly, in its assumption that there is no significant difference between the grand jury and the trial records because North’s “counsel does not cite to *868even a single line of trial testimony that indicates either a change from the witness’ grand jury testimony or any other evidence of taint.” Id. at 923. Pragmatism is doubtless a virtue, but its invocation cannot override the Fifth Amendment, Kastigar, and Rinaldi.4
In giving the IC a Kastigar clean bill of health, the District Court emphasized the warnings that were given to witnesses who appeared before the grand jury:
Beginning in July, 1987, the lawyers and investigators began instructing potential witnesses during interviews not to repeat any of the immunized testimony they may have been exposed to. When the grand jury reconvened in September, grand jury witnesses were formally instructed on matters related to immunized testimony.
Kastigar Memo, 698 F.Supp. at 311.5 The District Court went on to note that “a limited number of cooperating witnesses agreed to avoid exposing themselves to any of the immunized testimony elicited by Congress” and that Associate Independent Counsel “were apparently careful to avoid broad, rambling questions that might inadvertently invite generalized answers that comprehended facts not personally known to the witness but learned from immunized testimony.” Id. at 312.
We conclude that the District Court’s reliance on warnings to witnesses (to avoid testifying as to anything they had learned from North’s immunized testimony) was not sufficient to ensure that North’s testimony was not used. As North argues, “witnesses could not possibly filter each answer through the court’s hypothetical ‘prior knowledge’ test.” Brief for Appellant at 19 n. 28. The fact that the District Court reviewed transcripts of testimony before the grand jury in camera would have alerted the Court to the presence of North’s immunized testimony only if it were clearly identified as such. Such a review could not have disclosed the unattributed inclusion of immunized testimony in other evidence and is defective. The only proper remedy is the searching Kastigar inquiry prescribed in Section (E), infra.
D. Appropriate Legal Standards On Remand
To assist the parties and the District Court, we offer some further observations on the legal standards to be applied on remand. First, it is important to note what is not at issue here. In certain situations, a grand jury may be presented with incompetent evidence — for example, physical evidence seized in violation of the Fourth Amendment, or hearsay evidence, or evidence resulting from the violation of grand jury secrecy rules. In such circumstances, it is clear that dismissal of the indictment is not necessary. Midland Asphalt Corp. v. United States, 489 U.S. 782, 109 S.Ct. 1494, 103 L.Ed.2d 879 (1989); United States v. Calandra, 414 U.S. 338, 94 S.Ct. 613, 38 L.Ed.2d 561 (1974); United States v. Blue, 384 U.S. 251, 86 S.Ct. 1416, 16 L.Ed.2d 510 (1966); Lawn v. United States, 355 U.S. 339, 78 S.Ct. 311, 2 L.Ed.2d 321 (1958); Costello v. United States, 350 U.S. 359, 76 S.Ct. 406, 100 L.Ed. 397 (1956) (roughly, the “Costello-Calandra rule”). In essence, the Costello-Calandra rule says that a facially valid indictment need not be dismissed sole*869ly because the grand jury has considered evidence that would be inadmissible at trial because that evidence was obtained in violation of some constitutional or statutory prohibition. The rule applies where the allegedly unlawful or unconstitutional action is independent of or prior to the consideration by the grand jury of that action’s consequences. The terms of the Fourth Amendment do not prevent a grand jury from contemplating papers that have been seized without a warrant and without probable cause; rather, it prohibits the seizure of those papers in the first instance. Similarly, grand jury secrecy rules prohibit the publication of grand jury proceedings, not the government’s use of those proceedings once the publication has occurred. The Costello-Calandra rule gives substance to this distinction.
As we explain in some detail below, that is not the situation before us. Here, what is prohibited and unconstitutional under the Fifth Amendment and Kastigar is the very presentation of the immunized testimony. Where immunized testimony is used before a grand jury, the prohibited act is simultaneous and coterminous with the presentation; indeed, they are one and the same. There is no independent violation that can be remedied by a device such as the exclusionary rule: the grand jury process itself is violated and corrupted, and the indictment becomes indistinguishable from the constitutional and statutory transgression. The Costello-Calandra rule depends upon a distinction between the prohibited action and the presentation to the grand jury of the fruits of that prohibited action. Kastigar prohibits use. There is no antecedent or prior wrong to be remedied, but use is a wrong that goes to the quick of the indictment. This distinction eludes the IC and the District Court; it becomes clearer, however, upon a comparison of cases from other circuits.
In United States v. Garrett, 797 F.2d 656 (8th Cir.1986), the defendant was convicted of conspiracy to distribute cocaine. He appealed on the grounds that the grand jury that indicted him was the same grand jury to which he had testified on related matters under a grant of use immunity, and therefore his Fifth Amendment right was violated. The district court held no evidentiary hearing. The Eighth Circuit reversed and remanded for an evidentiary hearing on the grand jury issue. The government argued, much as it does here, that under Costello (which held that the grand jury clause of the Fifth Amendment does not require dismissal of an indictment that was based solely on hearsay evidence), and its progeny “courts may not dismiss or question an indictment, valid on its face, on the ground that the grand jury considered incompetent evidence, including evidence obtained in violation of an individual’s fifth amendment privilege.” Garrett, 797 F.2d at 660. Agreeing with the Ninth Circuit’s decision in United States v. Zielezinski, 740 F.2d 727, 732 (9th Cir.1984), the Garrett court rejected the government’s Costello analogy because “Costello simply does not consider the power of a court to look behind or dismiss an indictment where there is a strong likelihood that the grand jury process itself violated the witness’s fifth amendment privilege.” Garrett, 797 F.2d at 661.
In Zielezinski, an Arizona firefighter under a grant of use immunity testified before a grand jury that he had used cocaine once, but denied further involvement. Other grand jury witnesses identified the defendant as a source and user of cocaine. The grand jury indicted him for drug offenses and perjury. The government submitted to the trial court grand jury transcripts and case-agent reports in order to establish the requisite independent sources. Defense counsel never saw the materials, which the court reviewed in camera. The Ninth Circuit remanded for an evidentiary hearing at which the government would be required to show independent sources, noting that “[t]he government cannot simply provide transcripts to the court, in camera, and assume that it has met its Kastigar burden. Only a hearing can convincingly establish that the command of the Fifth Amendment has been satisfied.” Zielezinski, 740 F.2d at 734.
*870In United States v. Hampton, 775 F.2d 1479 (11th Cir.1985), the defendant gave immunized testimony to a Florida state grand jury, portions of which played a role in his subsequent indictment by a federal grand jury on charges involving the same events. For at least part of the investigation, federal investigators were using state materials and took no measures to insulate themselves from immunized testimony. The Eleventh Circuit reversed the conviction, holding that the district court erred in its conclusion that those of Hampton’s statements that were not immunized sufficed as an independent source for all the evidence that the grand jury considered. The court stated that “Kastigar and its progeny require dismissal of an indictment of a previously immunized witness unless the government can demonstrate that ‘none of the evidence presented to the grand jury is derived, directly or indirectly, from the immunized testimony....’” Id. at 1489 (quoting United States v. Byrd, 765 F.2d 1524, 1530 (11th Cir.1985)) (emphasis supplied in Hampton).
In United States v. Beery, 678 F.2d 856 (10th Cir.1982), a debtor was convicted of withholding a document and concealing assets in a bankruptcy. The debtor had been granted use immunity under 11 U.S.C. § 25(a)(10) (1976), the immunity provision of the Bankruptcy Act of 1898. He then claimed that the trustee had used the immunized testimony in testifying before the grand jury. The Tenth Circuit found the government’s assertions conclusory and the trial court’s findings insufficient. It therefore remanded for a hearing that would “afford the Government an opportunity to meet its burden of proof as to its sources of its evidence presented to the grand jury and at trial, with any response the defendant may have.” Beery, 678 F.2d at 863. The court also noted that the Costello principle was not necessarily applicable “where what was transpiring before the grand jury would itself violate a constitutional or statutory privilege.” Id. at 860 (citing Calandra, 414 U.S. at 346, 94 S.Ct. at 619).
Garrett and Zielezinski both rejected the approach of the Second Circuit in United States v. Hinton, 543 F.2d 1002 (2d Cir.), cert. denied, 429 U.S. 980, 97 S.Ct. 493, 50 L.Ed.2d 589 (1976), and its progeny. In Hinton, the defendant testified under a grant of use immunity and gave some 200 pages of testimony to a grand jury concerning her involvement in a narcotics distribution ring. Two years later, that same grand jury indicted her. The Second Circuit reversed Hinton’s conviction because
[t]he prospect of peering into the grand jurors’ minds, or of examining them individually, to ascertain whether Hinton’s testimony was improperly used, is both impractical and unpalatable.... [A]s a matter of fundamental fairness, a Government practice of using the same grand jury that heard the immunized testimony of a witness to indict him after he testifies, charging him with criminal participation in the matters being studied by the grand jury, cannot be countenanced.
Id. at 1010. Thus, Hinton supports a per se rule requiring dismissal of the indictment where it is shown that the indicting grand jury has been exposed to any immunized testimony. Circuit law as established in United States v. De Diego, 511 F.2d 818 (D.C.Cir.1975), instructs us to allow the government an opportunity to make its case at a hearing, and therefore we decline to adopt the per se rule of Hinton.
The IC has pointed us to several cases that he claims support application of a Costello-Calandra treatment in an immunized testimony case. In Midland Asphalt Corp. v. United States, 489 U.S. 782, 109 S.Ct. 1494, 1499-1500, 103 L.Ed.2d 879 (1989), the Court stated that “[w]e have held that even the grand jury’s violation of the defendant’s right against self-incrimination does not trigger the Grand Jury Clause’s ‘right not to be tried.’ ” (citing Lawn v. United States, 355 U.S. 339, 349, 78 S.Ct. 311, 317, 2 L.Ed.2d 321 (1958)). The Court went on to state that “[ojnly a defect so fundamental that it causes the grand jury no longer to be a grand jury, or the indictment no longer to be an indictment, gives rise to the constitutional right not to be tried.” Id. The Court found that the alleged violation of a grand jury secre*871cy rule, Fed.R.Crim.P. 6(e) (prohibiting government attorneys’ disclosure of matters before the grand jury), did not give rise to such a right. Midland Asphalt, 109 S.Ct. at 1499-1500. North’s whole point, of course, is that in his situation his widely disseminated testimony caused “the grand jury no longer to be a grand jury,” and we conclude that such may have been the case; at the very least, it is impossible to tell from the record before us.
The IC also points to United States v. Society of Independent Gasoline Marketers of America, 624 F.2d 461, 473-74 (4th Cir.1979), cert. denied, 449 U.S. 1078, 101 S.Ct. 859, 66 L.Ed.2d 801 (1981) (hereafter “SIGMA ”), as support for the proposition that “the Costello-Calandra principle has been applied to claims that the Government has improperly used immunized testimony.” Brief for Appellee at 13 n. 21. SIGMA fails to recognize the violation-of-process distinction pointed out in cases such as Beery and Garrett, and to that extent we decline to follow the Fourth Circuit. The IC attempts to distinguish the grand jury cases on the grounds that they all involved the government itself presenting immunized testimony, whereas in the present case it is presented by witnesses, if presented at all. Kastigar prohibits “use,” however, regardless of the conduit through which the government passes the testimony. The fact that Congress or a government witness, rather than the IC personally, provides compelled testimony to the grand jurors is legally irrelevant under Kastigar. The IC agreed that some of the grand jury witnesses had been exposed, Transcript of Kastigar Hearing at 221 (Apr. 25, 1988) (JA at 756), and the issues of the replacement jurors’ exposure, noted infra at Section (E), and of the effectiveness of the warnings, described supra at 868, strengthen us in our conclusion that it was error for the District Court to fail to hold a full Kastigar hearing concerning the content as well as the sources of the witnesses’ testimony.
We note again that use of immunized testimony before the grand jury could possibly lead to dismissal of the indictment. Apparently aware of this possibility, the IC protests that he sealed and filed (or “canned”) both evidence and prosecution theories prior to North’s congressional testimony. It is not clear to what extent the District Court saw and relied on these materials, or what part they played in the District Court’s review. See Kastigar Memo, 698 F.Supp. at 315-16 (listing materials reviewed). The District Court reviewed both sealed and unsealed materials. The sealed materials include the in-court testimony of IC Walsh; transcribed portions of the grand jury proceedings, including exhibits; the transcript of the voir dire of the replacement grand jurors; transcripts of interviews with General Richard V. Secord; a subpoena index; correspondence between the Congress and the IC concerning use immunity; and the so-called “Douglass file,” a collection of papers noting instances of exposure to the immunized testimony on the part of the IC and his staff. The sealed materials also included “[t]wo bound volumes of material establishing independent ‘leads’ to all trial witnesses providing substantive information who may be called in the government’s case-in-chief.” Id. at 315.
At oral argument, North’s counsel asserted that the canned materials played no part in the District Court’s review:
The interviews and any materials that had been sealed, so-called canned material, was not given to the District Court judge, although it had been filed with the District Court while the investigation was ongoing. There was an order, which is in the record, that that material was then transferred back to the Office of Independent Counsel for preservation, in ease it was ever needed, so that the interviews with these witnesses were not before the trial judge. He didn’t consider those in making his determination.
Transcript of Oral Argument at 20-21. Counsel for the IC did not contest this proposition, except to note that after the trial North had access to grand jury testimony and trial testimony concerning the three counts on which he was convicted, as well as access to the two volumes of leads noted by the District Court. Transcript of *872Oral Arg. at 50. See also United States v. Poindexter, No. 88-0080-02 (D.D.C. Apr. 28, 1988) (J.A. at 287-88) (order to the Court Security Officer (“CSO”) that he remove from the Office of the Clerk of the Court the material filed there under seal by the IC, and further instructing the CSO that the material be deposited in the sensitive compartmented information facility maintained by the IC). On the current record, therefore, we cannot determine the proper weight to afford these materials. On remand, the record must be clear and specific about the District Court's review of and reliance upon any canned testimony in its Kastigar determination.
E. Conclusion
North also asserts that a full Kastigar hearing is in order concerning the grand jury which was in recess from 29 June 1987 to 2 September 1987. Kastigar Memo, 698 F.Supp. at 308. North’s immunized testimony before Congress began on 7 July 1987 and ended 14 July 1987. No matter how many warnings the grand jurors were given, North argues, they were out of the presence of court and counsel for two months. During one of these weeks North was testifying before Congress. During the other seven weeks his testimony was disseminated widely and analyzed thoroughly. In addition, two replacement grand jurors were qualified after the- immunized testimony had been taken, as the District Court noted: “Neither grand juror was questioned in any detail concerning any knowledge either might have of the content or nature of the immunized testimony. The records of the grand jury indicate that in the normal course of later events they were adequately warned.” Id. at 311 n. 13. Although the government’s possible use of compelled testimony via the grand jury and trial witnesses concerns us most among North’s voluminous protestations, factors such as the grand jury’s recess during the daily, ubiquitous broadcast of North's immunized testimony, and the apparent decision of the District Court not to inquire in any detail as to the possible taint of the replacement grand jurors cause us to note with even greater concern the District Court’s decision not to hold a full-blown, item-by-item Kastigar hearing. The assertion that there was “solid proof and ample probable cause to indict,” id. at 315, even if true, cannot replace a Kastigar inquiry. Coerced confessions and compelled testimony may often supply proof and cause, but that fact does not diminish their constitutional offensiveness in virtually all uses.
The District Court also stated that “[t]he grand jurors were specifically, repeatedly and effectively instructed to avoid exposure to any immunized testimony.... Many more warnings were given during the course of the grand jury’s tenure.” Id. at 309. There is no evidence that the warnings to the grand jurors were effective, however, because grand jury deliberations are not transcribed and therefore could not have been part of the record reviewed by the Court. These concerns underscore our conclusion as expressed above that the present convictions cannot stand. We are not persuaded, however, to extend our holding and require an unprecedented Kastigar -type hearing concerning possible exposure of individual grand jurors through the media.
Nonetheless, as to witness exposure, such a hearing is required.
The convictions are vacated and the case is remanded to the District Court. On remand, if the prosecution is to continue, the District Court must hold a full Kastigar hearing that will inquire into the content as well as the sources of the grand jury and trial witnesses’ testimony. That inquiry must proceed witness-by-witness; if necessary, it will proceed line-by-line and item-by-item. For each grand jury and trial witness, the prosecution must show by a preponderance of the evidence that no use whatsoever was made of any of the immunized testimony either by the witness or by the Office of Independent Counsel in questioning the witness. This burden may be met by establishing that the witness was never exposed to North’s immunized testimony, or that the allegedly tainted testimony contains no evidence not “canned” by the prosecution before such exposure oc*873curred. Unless the District Court can make express findings that the government has carried this heavy burden as to the content of all of the testimony of each witness, that testimony cannot survive the Kastigar test. We remind the prosecution that the Kastigar burden is “heavy” not because of the evidentiary standard, but because of the constitutional standard: the government has to meet its proof only by a preponderance of the evidence, but any failure to meet that standard must result in exclusion of the testimony.
If the District Court finds that the government has failed to carry its burden with respect to any item or part of the testimony of any grand jury or trial witness, it should then consider whether that failure is harmless beyond a reasonable doubt. If the District Court concludes that the government’s failure to carry its burden with respect to that particular witness or item is harmless beyond a reasonable doubt, the District Court should memorialize its conclusions and rationales in writing. If the government has in fact introduced trial evidence that fails the Kastigar analysis, then the defendant is entitled to a new trial. If the same is true as to grand jury evidence, then the indictment must be dismissed.
II. Jury Unanimity Instruction
North alleges error as to Count 9 in the trial court’s refusal to give a specific unanimity instruction. The Court gave a general unanimity instruction:
The verdict must represent the considered judgment of each juror. In order to return a verdict on any aspect of this case it is necessary that each juror agree to the verdict. Your verdict must be unanimous.
In addition to this instruction, North contends that he was entitled to further instruction directing the jury that it must be unanimous as to the specific act (or acts), method, mode or manner by which North violated the statute as charged in Count 9. Upon review of the facts of this case and the appropriate authorities, we conclude that the District Court committed reversible error as to Count 9 in its refusal to include a specific unanimity requirement in its instructions to the jury.
In 1982, in United States v. Mangieri, 694 F.2d 1270 (D.C.Cir.1982), we considered a defendant’s “argument ... that when the government seeks to convict for one offense by proving two or more acts, proof of either one being sufficient, the court must ... instruct jurors that they must be unanimous in their finding that the government has proven the same one (or more) act(s).” Id. at 1280. In Mangieri, Chief Judge Wald, writing for a unanimous panel, noted “that the District of Columbia Court of Appeals has announced a rule requiring an instruction on the need for unanimity on the particular acts on which a guilty verdict is based.” Id. at 1281 (citing Hack v. United States, 445 A.2d 634, 641 (D.C.App.1982)). The Mangieri panel went on to note the reasoning underlying the District of Columbia rule, that is, “ ‘the possibility of a nonunanimous verdict, when one charge encompasses two separate incidents,’ ” so that a judge should (and under the District of Columbia’s rule must) “ ‘instruct the jury that if a guilty verdict is returned the jurors must be unanimous as to which indictment or incident they find the defendant guilty.’ ” Mangieri, 694 F.2d at 1281 (quoting Hack, 445 A.2d at 641 (other citations omitted)). We described the District of Columbia’s rule as “sensible and appropriate — and we urge[d] trial courts to employ the instruction without request in cases” where the possibility of non-unanimity as to specifics of the offense exists. Id.
Nonetheless, in Mangieri we did not reverse. The defendant had not requested a specific unanimity instruction. Despite our urging that the instruction should be given without request, we noted that “[t]his circuit, along with others, has not heretofore adopted a rule requiring the particularized instruction.” Id. Therefore, we examined the context of the entire instruction and the charge, and subjected the allegation to a “plain error” analysis. Finding no plain error, we affirmed.
*874More recently, in United States v. Hubbard, 889 F.2d 277 (D.C.Cir.1989), we confronted the same argument in the context of a defendant who had not objected to the general instruction given by the trial court and had made no request for a specific unanimity instruction. Again, we rejected the defendant’s specific-unanimity-instruction argument under a plain error analysis, but we reiterated that “[t]his Circuit strongly approved a District of Columbia Court of Appeals rule requiring an instruction on the need for unanimity on the particular acts on which a guilty verdict is based.” Id. at 279 (citing Mangieri).
In the present case, we do not confront a specific-unanimity-instruction question in a plain error context. North did request the instruction from the trial court and did object to the court’s refusal to give it. Therefore, the issue is before us for definitive resolution. We must determine whether the refusal to give the requested instruction was reversible error. We conclude that it was.
A. The Standard
Although we have not previously squarely faced this issue in other than a plain error context, other circuits have. In United States v. Gipson, 553 F.2d 453 (5th Cir.1977), the Fifth Circuit considered an appeal by a defendant who had been charged in one count with selling or receiving a stolen car that had moved in interstate commerce in violation of 18 U.S.C. § 2313. The Fifth Circuit noted that under the instructions actually given in that case, the guilty verdict could have resulted from each individual juror finding “that the defendant perform[ed] one of ... six prohibited acts — receiving, concealing, storing, bartering, selling, or disposing — on a stolen vehicle moving in interstate commerce that the defendant knew to be stolen.” Id. at 458. Speaking for the court, Judge Wisdom noted that “Rule 31(a) of the Federal Rules of Criminal Procedure requires that a jury verdict in a federal criminal trial be unanimous,” and that Rule 31(a) “gives explicit recognition to a requirement that the Supreme Court has long assumed to inhere in a federal criminal defendant’s sixth amendment right to a trial by jury.” Id. at 456 (footnote omitted) (citing, inter alia, Andres v. United States, 333 U.S. 740, 748-49, 68 S.Ct. 880, 884-85, 92 L.Ed. 1055 (1948)). Thus, the Fifth Circuit concluded, an instruction that permits the jury to return a guilty verdict where all jurors agree that he is guilty of something is not sufficient. The defendant’s right to a unanimous verdict is not adequately “protected unless [the] prerequisite of jury consensus as to the defendant’s course of action is also required.” Gipson, 553 F.2d at 458 (footnote omitted). Finally, the Gipson court held that “[b]ecause it is impossible to determine whether all of the jurors agreed that the defendant committed acts falling within one of the two conceptual groupings, we cannot say that the district court’s instruction was harmless beyond a reasonable doubt....” Id. at 459 (citing Chapman v. California, 386 U.S. 18, 87 S.Ct. 824, 17 L.Ed.2d 705 (1967)). Thus, the court reversed and remanded for a new trial.
In United States v. Beros, 833 F.2d 455 (3d Cir.1987), the Third Circuit considered the specific unanimity question. In that case the indictment charged a union official with embezzling, stealing, abstracting or converting to his own use funds belonging to the union. Like the defendant in Gip-son, and North in the present case, the official had requested a specific unanimity instruction in the district court. The Third Circuit noted that each of the counts alleged “four separate and distinct theories of criminal activity: embezzlement, abstraction, stealing and conversion.” Id. at 461. It further noted that “[e]ach count also enumerates several acts upon which a finding of guilty could be predicated.” Id. In that circumstance, the court concluded that “[i]t is plainly not enough that the jury was unanimous in finding one theory on which it believed Beros culpable. The jury needed also to match that finding to another unanimous finding regarding a particular act.” Id.
In an opinion by Judge Higginbotham, the Beros court described the circum*875stances that mandate a specific unanimity instruction:
When the government chooses to prosecute under an indictment advancing multiple theories, it must prove beyond a reasonable doubt at least one of the theories to the satisfaction of the entire jury. It cannot rely on a composite theory of guilt, producing twelve jurors who unanimously thought the defendant was guilty but who were not unanimous in their assessment of which act supported the verdict.
Id. at 462. Thus, the Third Circuit concluded that the Sixth Amendment requires the jury to be unanimous as to the specific act and theory underlying the defendant’s guilt and that the reviewing court “must be certain that the jury was properly instructed to achieve” that unanimity. Id. (citing United States v. Peterson, 768 F.2d 64, 67 (2d Cir.), cert. denied, 474 U.S. 923, 106 S.Ct. 257, 88 L.Ed.2d 264 (1985)). Expressly distinguishing our decision in Mangieri where the defendant had not requested the specific unanimity instruction, the Beros court, like the Fifth Circuit in Gipson, subjected the question to a harmless error analysis and vacated Beros’s convictions on the counts under review. Id. at 462-63.
The Sixth Circuit faced the specific unanimity issue in United States v. Duncan, 850 F.2d 1104 (6th Cir.1988), aff'd without op. on appeal after remand, 881 F.2d 1077 (6th Cir.1989), cert. denied sub nom. Downing v. United States, — U.S.-, 110 S.Ct. 732, 107 L.Ed.2d 751 (1990). In Duncan, each of two counts of the indictment charged the defendant with criminal acts relating to the filing (Count 3) and preparation (Count 5) of a false tax return. As to each of those counts, the allegations and the prosecution’s evidence supported the inclusion of two distinct false statements in the relevant tax return. Hence, the possibility existed that one or more jurors might have found that the defendant acted criminally with respect to one of the false statements, even though the juror (or jurors) harbored doubt as to the other statement. Thus, a jury, unanimous as to guilt, might have been divided as to the specific act upon which that conclusion of guilt was founded. In considering the defendant’s argument that it was error for the trial judge not to have offered a specific unanimity instruction, the Sixth Circuit first considered the question, “Must the jury’s verdict actually have been unanimous as to one or the other statement?” Id. at 1111. The court held that “unanimity on alternatives is necessary when ‘discrete acts are alleged in a single count, such as charges of separate false statements, any one of which is sufficient to convict.’ ” Duncan, 850 F.2d at 1113 (quoting United States v. Ferris, 719 F.2d 1405, 1407 (9th Cir.1983) (Kennedy, J.)).
Having reached that conclusion, the Sixth Circuit then considered the question, “[Gjiven the necessity for a unanimous verdict, [was] the trial judge ... required to instruct the jury of that necessity[?]” Duncan, 850 F.2d at 1113. Relying heavily on Judge Higginbotham’s discussion in Beros, the Duncan court answered that question in the affirmative:
‘When it appears ... that there is a genuine possibility of jury confusion or that a conviction may occur as a result of different jurors concluding that the defendant committed different acts, the general unanimity instruction does not suffice.
To correct any potential confusion in such case, the trial judge must augment the general instruction to insure the jury understands its duty to unanimously agree to a particular set of facts. ’
Duncan, 850 F.2d at 1114 (quoting Beros, 833 F.2d at 461) (emphasis supplied in Duncan) (other citations omitted).
We adopt the holding of our sister circuits in Duncan, Beros, and Gipson and conclude that the trial court erred in refusing to instruct that in order to return a unanimous verdict of guilty on a count involving multiple distinct underlying acts, jurors are required to be unanimous as to the specific act by which the defendant violated the law. We hold that in cases where there is a danger of a fragmented verdict the trial court must upon request offer a specific unanimity instruction.
*876In discussing the application of this rule to the present case, we will further delineate the circumstances warranting such an instruction.
B. Application to the Present Case
At the outset, we recognize that as a rule a general instruction on unanimity like the one given in the present case-advising the jury that its members must unanimously agree on any aspect of the case as to which it renders a verdict-protects the defendant's right to a unanimous jury decision. Duncan, 850 F.2d at 1113. A further safeguard in the form of a particularized instruction is required, however, in the face of "a genuine risk that the jury is confused or that a conviction may occur as the result of different jurors concluding that the defendant committed different acts." Id. at 1114. The present case presents such a genuine risk. Analyzing the question in common-law terms, we would state that in order to return a guilty verdict under Count 9, the jury was required to agree that the defendant did commit a charged actus reus with a mens rca. Cf. Duncan, 850 F.2d at 1111. Count 9 charged that North, having custody of NSC documents, "willfully and knowingly did conceal, remove, mutilate, obliterate, falsify and destroy and did cause to be concealed, removed, mutilated, obliterated, falsified and destroyed records, papers and documents filed and deposited in a public office. . . ." JA at 260-61.6 In his jury instruction on Count 9, the trial judge summarized the indictment as charging North with destroying, altering, and removing documents from mid- to late November 1986. JA at 645. In effect, then, the jury had three alternative theories of destroying, altering, or removing on which it might have convicted North under section 2071(b).
Where several factual predicates support a guilty verdict, a defendant is entitled to unanimous agreement among the jury as to which of those "alternative factual predicates" provided a basis for conviction. Duncan, 850 F.2d at 1112 (citing cases). As a general rule, when an indictment charges several "distinct conceptual groupings" of activities in an individual count, as opposed to "a single conceptual grouping of related facts," the jury must agree unanimously as to which of these distinct groupings the defendant is guilty. Id. at 1113. See Gipson, 553 F.2d at 458 (actions are conceptually indistinct when they are interrelated or when they cannot be characterized separately from each other). When a statute criminalizes false statements, for example, each false statement charged in a single count is properly treated as a distinct conceptual grouping; to convict, the jury must unanimously ~agree upon which one of those statements the defendant made. See Mangieri, 694 F.2d at 1281; United States v. Ryan, 828 F.2d 1010, 1019 (3d Cir.1987); see also Beros, 833 F.2d at 460-63 (three alternative trans~ctions charged in same count as occasions of "embezzlement, stealing, abstracting, or converting to own use" require specific unanImity in verdict); United States v. Peterson, 768 F.2d 64, 67 (2d Cir.), cert. denied, 474 U.S. 923, 106 S.Ct. 257, 88 L.Ed.2d 264 (1985) (two separate instances ch'arged in single count of drug possession require specific unanimity in verdict).
In North's case, the factual predicates on which the indictment was based are, in our view, distinct enough to necessitate specific unanimity. North testified that he destroyed documents beginning in late October 1986 and that he continued to do so until he was fired in November 1986. At Casey's instruction, he destroyed a ledger of the Contra operating fund, Transcript *877of Testimony (“Tr.”) at 7138-39; acting on his own, in order to avoid jeopardizing clandestine supporters of American activities in the Middle East and Central America, Tr. at 7578, he also destroyed documents concerning the Iranian arms sales and Contra support initiatives, Tr. at 7561-63, 7574-75. He explained that he regarded the destroyed documents as part of his personal files, Tr. at 7560, and, therefore, did not consider his actions unlawful.
North also testified that, on McFarlane’s instructions, he altered five official documents — apparently System IV NSC documents — relating to the Iranian arms sales. Tr. at 6905. North thought that altering only the five or six documents indicated by McFarlane “didn’t ... [make] any sense,” Tr. at 6906, because other documents included equally sensitive information about Contra support. North said that he did not consider the alterations unlawful because he had prepared the documents in question for McFarlane. Tr. at 6907.
Finally, North testified that after he was fired, he removed documents from his NSC office on the advice of Secord’s counsel. Tr. at 7109, 7113. He returned the documents a few days later on the advice of his present counsel, whom he had retained in the intervening period. Tr. at 7117.
Thus, the jury could have found that North violated section 2071(b) in several different ways. The circumstances of his destruction, alteration, and removal of documents were distinct; any of those activities could serve as an underlying criminal act. Furthermore, the evidence bearing on North’s knowledge of the lawfulness of his actions — and, in effect, on the criminality of his intent — varied from instance to instance. Each of the possible predicates for a conviction on Count 9, therefore, required distinct, individuated proof. As a result, we conclude that the jury had to agree unanimously as to which, if any, of these combinations of actus reus and mens rea actually occurred, and the trial court should have so instructed.
The IC attempts to distinguish Gipson, Beros, and Ferris on the argument that the charge in Count 9 “involves a continuing course of conduct, rather than conceptually distinct episodes of destruction, alteration and removal....” Brief for Appellee at 66 (emphasis supplied). This argument is not supportable either on the law or the facts. Although the presence of a “conceptual distinction” in the acts charged was important to other circuits in some of the cited cases, see, e.g., Gipson, 553 F.2d at 458, that term is simply a useful formulation of a circumstance requiring the specific unanimity instruction. The exact parameters of the universe of cases in which the instruction must be given cannot be determined by a niggling construction of that phrase. In Peterson, the Second Circuit noted the Fifth Circuit’s use of that phrase as a qualifier in Gipson. The Second Circuit, in an opinion by Judge Friendly, read the Gipson court’s use of “the ‘distinct conceptual grouping' qualification” as “referring] to situations where the same act is characterized in different ways, each of which constitutes a crime under the same count of an indictment.” Peterson, 768 F.2d at 67 (footnote omitted). The Peterson court went on to note that “the two instances of possession offered in support of [a single count] ... would constitute ‘distinct conceptual groupings’ despite their close coincidence in time and similarity in nature.” Id.
Likewise, after considering the Gipson court’s use of the phrase and Judge Friendly’s construction of it in Peterson, the Sixth Circuit concluded in Duncan that “a count containing two false representations ... is normally treated as containing two distinct conceptual groupings.” Duncan, 850 F.2d at 1113 (internal quotations omitted). The Duncan court went on to state in its analysis of the necessity for a specific unanimity instruction, “the touchstone has been the presence of a genuine risk that the jury is confused or that a conviction may occur as the result of different jurors concluding that a defendant committed different acts.” Id. at 1114 (emphasis supplied). Because the indictment in the present case charged several distinct acts of concealing, removing or falsifying documents, the Peterson/Duncan analysis of the Gipson phrase “distinct conceptual grouping” *878seems to us apposite, and the danger that a jury unanimous as to guilt could have been divided as to the specific act committed seems most real.
As the Ninth Circuit has stated, “[w]hen it appears ... that there is a genuine possibility of jury confusion or that a conviction may occur as a result of different jurors concluding that the defendant committed different acts, the general unanimity instruction does not suffice.... [T]he trial judge must augment the general instruction to ensure the jury understands its duty to unanimously agree to a particular set of facts.” United States v. Echeverry, 719 F.2d 974, 975 (9th Cir.1983) (emphasis supplied) (modifying 698 F.2d 375 (9th Cir.1983)) (adopted in Beros, 833 F.2d at 455; Duncan, 850 F.2d at 1114). Count 9 presents just such a situation.
It is certainly a genuine possibility, and perhaps not an unlikely one, that individual jurors or groups of jurors differed on whether North performed the separate acts charged under Count 9 with the requisite intent.7 For example, some jurors may have concluded that North knew only that destroying official documents was unlawful, while other jurors may have believed that he knew only that altering System IV documents was unlawful, and still others may have believed that he knew only that removing documents from his office aftér being fired was unlawful. It is also possible, albeit less likely, that despite North’s testimony, jurors could have disagreed as to which actus reus North committed, regardless of his intent. Because “the permutations that can support a valid conviction are varied and several,” Beros, 833 F.2d at 462, the possibility that the jury did not reach a verdict of specific unanimity is significant and real. Consequently, we cannot conclude that the District Court’s refusal to give a particularized unanimity instruction was harmless error. We reverse Count 9 on this ground.
III. Authorization
North argues that his convictions on Counts 6 and 9 must be reversed because the jury was improperly instructed concerning North’s claimed authorization from his superiors to do the acts underlying those counts. He raises two arguments that at least appear to be conceptually distinct. First, North asserts that under our decision in United States v. Barker, 546 F.2d 940 (D.C.Cir.1976), the jury should have been instructed to return a verdict of not guilty if it found the necessary elements of a so-called “authorization defense.” That is, he claims that he was entitled to an instruction that reasonable reliance on the apparent authority of one’s superiors is an absolute defense. We hold that the District Court did not err in refusing to give an authorization defense instruction. Second, North claims that the District Judge erred when he instructed the jury to ignore all evidence of authorization in deciding whether North had the requisite intent in either count unless “the defendant was specifically ordered and directed by a superior to act contrary to the law, and if no alternative was available to him to comply with the order by other lawful means ... [and if] he reasonably believed the order was legally proper.” JA at 674-75. We hold that the District Court erred in limiting the jury’s consideration of the evidence of authorization with reference to Count 9, but not as to Count 6.
A. Authorization Defense
North claims that the District Court erred by refusing to instruct the jury that authorization is a complete defense requiring acquittal if supported by the evidence. This argument is raised separately and distinctly from the claim that the jury was improperly constrained in its consideration of the evidence of authorization. North asserts in his brief that “there is an enormous difference between (1) an instruction that authorization is merely relevant to intent and (2) an instruction that authoriza*879tion is a defense that requires acquittal if supported by the evidence.” Brief for Appellant at 37. Specifically, North requested the following instruction:
If you find that LtCol North acted in good faith on a superior’s apparent authorization of his action, and that his reliance was reasonable based on the facts as he perceived them, that is a complete defense to [Counts Six and Nine].
JA at 2459. North argues that he was entitled to such an instruction under our decision in United States v. Barker, 546 F.2d 940 (D.C.Cir.1976), which, he claims, establishes an authorization defense in this Circuit quite apart from the question of intent. North faults the District Court for its failure to follow Barker. Although North’s argument has an initial appeal because Barker is a previous case of our Circuit, we have read Barker, and reread it, and simply cannot find in it a rule of law to apply.
In Barker, we reversed the convictions of Bernard Barker and Eugenio Martinez, who participated in the burglary of Dr. Lewis Fielding’s office at the behest of E. Howard Hunt. Hunt, who was known to Barker and Martinez as a long-time CIA agent, worked under the supervision of John Ehrlichman in the White House and was attempting to obtain information about Daniel Ellsberg, the source of the Pentagon Papers leak. Dr. Fielding was Ells-berg’s psychiatrist, and Hunt hired Barker and Martinez to break into Fielding’s office for the purpose of photographing Ells-berg’s file. That break-in led to charges under 18 U.S.C. § 241 against Barker and Martinez, among others, for conspiring to violate Dr. Fielding’s Fourth Amendment rights. The defendants claimed that they lacked the mens rea necessary for conviction because they had reasonably relied on Hunt’s authority to engage them in carrying out the burglary, and that the district court had erred by refusing to instruct the jury accordingly and by excluding evidence that would tend to establish their theory of the case.
All three judges issued separate opinions, two of which supported reversal on grounds that the defendants were entitled to put on evidence and have the jury instructed on the defense of good faith reasonable reliance on the apparent authority of Hunt. Judge Wilkey thought the case presented an exception to the usual rule that a mistake of law is no defense to a criminal charge. He observed first that it would be a mistake of law, not fact, for a police officer to search someone’s home or office in reliance on a warrant that was issued by a judicial officer who mistakenly believed that there was probable cause for the search:8 “It is readily apparent that few courts would countenance an instruction to a jury ... which advised that since the mistake in acting on an invalid warrant was one of law, it would not excuse the agent’s unlawful search.... [T]here is an overriding societal interest in having individuals rely on the authoritative pronouncements of officials whose decisions we wish to see respected.” 546 F.2d at 947 (opinion of Wilkey, J.) (emphasis in original) (footnotes omitted). Judge Wilkey thought that interest implicated only when the reliance was objectively reasonable under the circumstances (as it clearly would be for the officer relying on an invalid judicial warrant). See id. at 947-48 (opinion of Wilkey, J.).9 Judge Wilkey therefore concluded that the district court’s instruction that a mistake of law cannot be an excuse required reversal unless
there is no legal possibility of equating the reliance of Barker and Martinez on Hunt’s apparent authority with the reliance of a police officer on a judicial *880warrant subsequently held invalid. And this will be true if and only if Barker and Martinez could not show both (1) facts justifying their reasonable reliance on Hunt’s apparent authority and (2) a legal theory on which to base a reasonable belief that Hunt possessed such authority.
Id. at 949 (opinion of Wilkey, J.) (emphasis in original). Judge Wilkey went on to determine that Barker and Martinez could make both of those showings. As to the facts, Judge Wilkey thought there was evidence to support the conclusion that the defendants “honestly and reasonably believed they were engaged in a top-secret national security operation lawfully authorized by a government intelligence agency.” Id. at 949 (opinion of Wilkey, J.). They could meet the legal theory requirement as well, continued Judge Wilkey, on the grounds that it was plausible to believe at the time of the break-in that the President had the power to confer authority on his aides to conduct warrantless searches pertaining to foreign agents. See id.
Sitting by designation, Judge Merhige of the Eastern District of Virginia also thought the case fit into an exception to the “mistake of law is not an excuse” rule and analogized the case to situations in which a defendant acted on the basis of erroneous government advice, thereby making a criminal conviction unduly harsh. The quintessential examples mentioned by Judge Mer-hige were individuals acting in reliance on a statute later held to be unconstitutional or on a court decision that a statute is unconstitutional that is subsequently overruled. See 546 F.2d at 956 (opinion of Merhige, J.). In order to avoid convictions in those situations, Judge Merhige thought a defense should be available to a defendant who
(1) reasonably, on the basis of an objective standard, (2) relies on a (3) conclusion or statement of law (4) issued by an official charged with interpretation, administration, and/or enforcement responsibilities in the relevant legal field.
Id. at 955 (opinion of Merhige, J.). Responding to the fear that such a defense would reward public ignorance of the law to the detriment of the rule of law in general, Judge Merhige stated that “the defense requires that the individual either seek out or be cognizant of the official statement upon which he or she relies. Some knowledge of the law, verified by an independent and typically competent source, is required.” Id. Furthermore, the defense would be narrowed because “[t]he reasonableness of the reliance may dissipate if one depends on nonenforceable advisory opinions of minor officials.... Similarly, the defense does not extend to reliance on individuals, who ... have no interpretative or administrative responsibilities in the area associated with the legal concepts involved in the mistaken opinion or decision.” Id. at 956 (opinion of Merhige, J.).
North cannot even approach the showing that Judge Merhige’s formulation of the defense requires. North does not even claim that he relied on any “conclusion or statement of law,” let alone one “issued by an official charged with interpretation, administration, and/or enforcement responsibilities in the relevant legal field.” See id. at 955 (opinion of Merhige, J.). On the other hand, neither did Barker or Martinez, yet Judge Merhige voted that their convictions had to be reversed. Despite all that was recounted above, Judge Merhige concluded:
Barker and Martinez assert that they relied on Hunt’s authority as delegated from an intelligence super-structure controlled by the White House_ The Executive Branch ... is vested with substantive responsibilities in the field of national security, and decisions of its officials on the extent of their legal authority deserve some deference from the public. A jury may well find that John Ehr-lichman ... expressed or implied that the break-in of Dr. Fielding's office was legal ... and that Hunt ... passed the position on to the defendants, which they, acting as reasonable men, relied upon in performing the break-in.
Id. at 957 (opinion of Merhige, J.) (footnotes omitted).
We suppose we could simply ignore the reasoning of Judge Merhige’s *881opinion and merely infer the contours of an authorization defense from the facts in Barker that he thought warranted an authorization instruction. But the very premise of appellate review is that reasoning matters. Indeed, that is one of the crucial reasons why we are bound only by prior published opinions of this Circuit and not by other means of deciding cases. We do not think that any coherent principle can be gleaned from the Barker case because the reasoning of Judge Merhige’s opinion does not mesh with its outcome. In such a situation, we could not fault a district court solely for a failure to “follow” Barker.
North’s suggested instruction, quoted above, goes so far as to conjure up the notion of a “Nuremberg” defense, a notion from which our criminal justice system, one based on individual accountability and responsibility, has historically recoiled. In the absence of clear and comprehensible Circuit authority that we must do so, we refuse to hold that following orders, without more, can transform an illegal act into a legal one.10
B. Evidence of Authorization
1. Count 6
We conclude that Judge Ge-sell’s limitations on the jury’s consideration of authorization evidence were not prejudicial to North as to Count 6. If we compare the standard of criminal intent in 18 U.S.C. § 1505,11 the statute underlying North’s convictions on Count 6, with the authorization evidence he actually submitted at trial, the lack of any prejudicial effect from the judge’s instructions becomes clear.
Section 1505 mandates a fine or imprisonment, or both, for anyone who “corruptly, or by threats or force, or by any threatening letter or communication influences, obstructs, or impedes or endeavors to influence, obstruct, or impede ... the due and proper exercise of the power of inquiry under which any inquiry or investigation is being had by either House, or any committee of either House or any joint committee of the Congress .... ” Thus, absent evidence of threats or force, a person violates section 1505 by “corruptly” influencing, obstructing, or impeding a congressional investigation or attempting to do the same. Because Congress is not shown to have intended otherwise, “corruptly” should be understood by a jury and by a court to have its usual meaning. In general, common words in statutes should be given their common or popular meanings, in the absence of congressional definition. See, e.g., Perrin v. United States, 444 U.S. 37, 41-45, 100 S.Ct. 311, 313-15, 62 L.Ed.2d 199 (1979); United States v. Stewart, 311 U.S. 60, 63, 61 S.Ct. 102, 104-05, 85 L.Ed. 40 (1940); Old Colony R.R. Co. v. Commissioner, 284 U.S. 552, 560, 52 S.Ct. 211, 213-14, 76 L.Ed. 484 (1932); Martin v. Hunter’s Lessee, 14 U.S. (1 Wheat) 556, 571, 4 L.Ed. 97 (1816); United States v. Smith, 209 F.Supp. 907, 917 (E.D.Ill.1962); Svilokos v. State, Dep’t of Community Aff., 220 N.J.Super. 441, 532 A.2d 743, 744-45 (1987); Allgood v. Bradford, 473 So.2d 402, 411 (Miss.1985); 2A Sutherland Statutory Const. § 47.28, at 223 (4th ed.) and at 50 (Supp.1989). According to a standard dictionary, “corruptly” is the adverbial form of the adjective “corrupt,” which means “depraved, evil: perverted into a state of moral weakness or wickedness ... of debased political morality: characterized by bribery, the selling of political favors, or other improper political or legal transactions or arrangements.” Webster’s Third New International Dictionary 512 (1976). A “corrupt” intent may also be defined as *882“the intent to obtain an improper advantage for [one]self or someone else, inconsistent with official duty and the rights of others.” Ballentine’s Law Dictionary 276 (3d ed. 1969) (definition of “corruptly”).
Several courts of appeal, in upholding convictions under 18 U.S.C. § 1505, and its companion statute, 18 U.S.C. § 1503, which criminalizes corrupt obstructions of judicial proceedings, have said that the word ‘corruptly’ means nothing more than an intent to obstruct the proceeding. In so doing, they have not read the corrupt intent requirement out of the statute; rather, these cases have recognized that “constitutionally unprotected and purportedly illicit” conduct — behavior that is “not ... inadvertent, negligent, or even reckless[ly] non-purposeful” — reflects a “ ‘corrupt[ ]’ endeavor to interfere with the due administration of justice.” United States v. Jeter, 775 F.2d 670, 679 (6th Cir.1985), cert. denied, 475 U.S. 1142, 106 S.Ct. 1796, 90 L.Ed.2d 341 (1986). Clandestinely obtaining grand jury transcripts and selling them to targets of the grand jury’s investigation, id., or purposefully concealing documents subpoenaed by the IRS, United States v. Laurins, 857 F.2d 529, 536-37 (9th Cir.1988), or by a grand jury, United States v. Rasheed, 663 F.2d 843, 852 (9th Cir.1981), cert. denied sub nom. Phillips v. United States, 454 U.S. 1157, 102 S.Ct. 1031, 71 L.Ed.2d 315 (1982), have readily been held to meet the requisite corrupt standard.
For the conduct covered by section 1503 such a legal presumption may well be warranted because, after all, very few non-corrupt ways to or reasons for intentionally obstructing a judicial proceeding leap immediately to mind. The Fifth Circuit has made similar observations:
Although the special considerations surrounding a criminal trial have caused courts interpreting section 1503 to impute ‘corrupt’ intent to many practices, the independent significance of this term has not been suppressed.... [Wjhere a defendant has endeavored to obstruct a criminal proceeding, the ‘advantage inconsistent with the duties and rights of others’ is so clear that courts have often been willing to impute the desire to obtain such advantage on a per se basis.... [Sjection 1503 presupposes a proceeding the disruption of which will almost necessarily result in an improper advantage to one side in the case.
United States v. Reeves, 752 F.2d 995, 999 (5th Cir.), cert. denied, 474 U.S. 834, 106 S.Ct. 107, 88 L.Ed.2d 87 (1985).
But to import that legal presumption to section 1505 — and thus to assert that all endeavors to influence, obstruct or impede the proceedings of congressional committees are, as a matter of law, corrupt — would undoubtedly criminalize some innocent behavior. Unlike courts of law covered by section 1503, congressional committees are part and parcel of a political branch of government and therefore serve wide-ranging political functions not limited to a search for truth in accordance with formal rules. They may also have a far-flung investigative scope and evoke legitimate political jousting between the executive and legislative branches. No one can seriously question that people constantly attempt, in innumerable ways, to obstruct or impede congressional committees. An executive branch official, for example, might call the chairman of a congressional committee convened to investigate some wrongdoing and say, “We both know this investigation is really designed to embarrass the President (or a Senator), not to investigate wrongdoing. Why don’t you call it off?” The official surely intends to obstruct or impede the inquiry, but it does not necessarily follow that he does so corruptly. Similarly, a political activist might contact his representative and tell her that unless she stops spending her time pursuing a certain investigation rather than some other legislative endeavor, the activist’s group will oppose her reelection. Again, the activist is endeavoring to impede or obstruct the investigation, but is not necessarily doing so corruptly.
Even if we do not apply the presumption from section 1503 to indictments under section 1505, however, North was entitled only to the instruction on intent given, and to a jury that applied “corruptly” according to its usual definitions. He contends, never*883theless, that the trial court erred, in its intent instruction, by placing limitations on the jury’s use of his evidence of authorization. The trial court instructed that the jury could consider authorization on the question of intent, but only subject to the following limitations:
It [authorization] must be specific, not simply a general admonition or vague expression of preference. It must be sufficiently precise to assure a reasonable person that it was intended to apply in the circumstances that develop subsequently which were not otherwise specifically stated.
Finally, if an authorization can be satisfied by two different courses of action, one clearly legal and one illegal or of dubious legality and a person chooses the illegal or dubious course when other legal action would comply, authorization cannot be viewed as affecting intent.
JA at 675.
Although the trial court might well have omitted any reference to authorization, the instruction it actually gave apparently represents an attempt to synthesize the two opinions constituting the majority in Barker with United States v. Ehrlichman, 546 F.2d 910 (D.C.Cir.1976), decided by the same panel on the same day. From this synthesis, the trial court drew the three requirements that there be (1) specific instruction, (2) no alternative lawful means of compliance, and (3) a reasonable belief in the legal propriety of the order. Ehrlich-man contains language supporting the first requirement of a specific instruction. See 546 F.2d at 925. In Ehrlichman, the defendants were charged with conspiring to violate the civil rights of a psychiatrist by planning and conducting an unlawful search of his office. They relied on a claimed “national security exception” to the Fourth Amendment protections against unlawful searches and seizures. It was in the context of evaluating that specific defense that the Ehrlichman panel laid down the specific-instruction requirement. Ehr-lichman may be read beyond its holding when the specific-instruction requirement is extended beyond the Ehrlichman circumstances and is imposed on a defendant who asserts that he was properly authorized to do what he did and therefore lacked the necessary criminal intent regardless of the underlying act. The requirement of no-alternative-means-of-compliance is also a reasonable reading of Ehr-lichman and, at least on the Ehrlichman facts, seems to be a proper statement of the law.12 None of this, however, has a direct bearing on the facts of the present case.
North’s evidence, as we have demonstrated above, does not support a mistake-of-law defense. In effect, he is arguing that the jury should have been instructed or permitted to consider the authorization evidence not as it bore on his intent to commit the acts charged or the nature of the acts, but rather on his motive in committing the acts. This argument invites us to establish a rule that in determining whether a defendant charged with violating section 1505 acted corruptly, the trial judge should instruct the jury that in order to find the defendant guilty, it must find that he acted from a “corrupt motive.” We have seen no authority to this effect, and we cannot agree. Just as we noted above, there are myriad ways of “impeding” or “obstructing” congressional investigations that are not in themselves corrupt; so are there equally corrupt ways of impeding or obstructing Congress that do not proceed from corrupt motives. Allowing an official’s personal motive to exculpate otherwise corrupt obstructive conduct would give him license to “substitute for law his own notions of right, [which] would be in effect to subvert the law.” G. Williams, Criminal Law — The General Part § 241 (2d ed. 1961) (quoting Cr.L.Comm’rs., 7th Rep. (1843) Parl.Pap. xix 33).
The implications of a contrary view are stunning. Could a jury sympathetic to the *884official’s individual notion of morality exculpate a self-styled Robin Hood bureaucrat who concealed, altered, or destroyed documents that he knew Congress needed for its oversight of budgetary disbursements? Could a bigoted jury excuse a white supremacist official who altered documents eventually slated for Congress’s review of misuse of government set-asides by minority businesses? To hold that North was entitled to have the jury consider the authorization of his superiors because it bore on his motive for committing the acts in question does little more than restate the purported Barker defense which we already rejected above. Under either formulation, the defendant is enabled to escape the criminal consequences of his otherwise unlawful acts merely by asserting that his reason for committing the acts was that he was “following orders.”
If knowledge of unlawfulness were required in order to convict a defendant of violating section 1505, North’s argument might be more colorable. But this is not the case. Although the violation of this statute is a “specific intent” offense, “the mental state required for most ‘specific intent’ offenses does not involve knowledge of illegality.” Ehrlichman, 546 F.2d at 919 (footnote omitted). North received from the trial court the instruction that
[sjpecific intent requires that a person not only acted knowingly, voluntarily and deliberately, but that he acted with a bad purpose, having decided in his mind what he would do and that he then did something prohibited.
JA at 672-73. Thus, because knowledge of illegality was not required, he was not entitled to an instruction that the jury should consider authorization as bearing on knowledge of illegality. The jury was not empaneled to determine whether or not the defendant knew that his acts were illegal, but only whether “he specifically intended to do something the law prohibits, whether he knew of the law or not.” JA at 674. In this case, the act that the law prohibited was to “corruptly ... endeavor[ ] to influence, obstruct, or impede” a congressional inquiry. 18 U.S.C. § 1505. Because the District Court had correctly defined for the jury the required intent, and because “corruptly” and the other words in the statute are to be understood according to their common meanings, necessitating no specific definitional instructions from the court, we see no way in which the evidence of authorization would bear on the decisions the jury was required to make. If the jury was convinced beyond a reasonable doubt that North’s creation of a false chronology was an intentional (as defined in the instructions) endeavor corruptly to influence the congressional investigation (as defined in the common use and sense of those terms), then it was the jury’s duty to return a verdict of guilty. Whether or not he was “following orders” was immaterial to that decision, and there was no error in the trial court’s refusal to give the instruction.
2. Count 9
In Count 9, North was charged with violating 18 U.S.C. § 2071(b), which makes it a crime for anyone who has custody of “any record, proceeding, map, book, paper, document, or other thing, filed or deposited with any clerk or officer of any court of the United States, or in any public office, or with any judicial or public officer of the United States,” to “willfully and unlawfully conceal[ ], remove[ ], mutilate[], obliterate[ ], falsify[], or destroy[] the same_” (emphasis supplied). North was alleged to have violated this section by concealing, removing, and destroying a number of NSC documents concerning both the provision of aid and assistance to the Contras and the sale of arms to Iran, acting with the knowledge that doing so contravened an internal NSC regulation governing the proper means of handling documents. As both parties agree, a conviction under section 2071(b) requires that the government prove that North acted with knowledge that his conduct was unlawful.13
*885With regard to the relevance of authorization to the jury’s deliberations about North’s state of mind on this (and other) counts, the District Court instructed:
If the defendant was specifically ordered and directed by a superior to act contrary to the law, and if no alternative was available to him to comply with the order by other lawful means, you may weigh this authorization along with other facts in determining his specific intent, provided under the facts and circumstances he reasonably believed the order was legally proper.
However, authorization requires clear, direct instructions to act a given time in a given way. It must be specific, not simply a general admonition or vague expression of preference.... A person’s general impression that a type of conduct was expected, that it was proper because others were doing the same, or that the challenged act would help someone or avoid political consequences, does not satisfy the defense of authorization.
Finally, if an authorization can be satisfied by two different courses of action, one clearly legal and one illegal or of dubious legality, and a person chooses the illegal or dubious course when other, legal action would comply, authorization cannot be viewed as affecting intent.
JA at 674-75 (emphasis supplied).14
It may well have been acceptable if the District Court had said nothing at all about authorization when instructing the jury about intent and merely told them to consider all of the surrounding circumstances when deciding if North knew his actions were unlawful. Instead, the Dis-trict Judge decided that the jury could not consider at all the instructions, statements, and behavior of North’s colleagues, whether superiors or not, unless the evidence sufficed to warrant an “authorization defense” instruction to the jury. But whatever might have once been thought to constitute an “authorization defense” — see Section III(A), supra — it was error to preclude the jury from considering whatever evidence of authorization exists in the record as it bears on the jury’s determination of whether North had subjective knowledge of unlawfulness.15 As we have made clear above, authorization from one’s superiors cannot convert illegal activity into legal, yet it surely can affect a defendant’s belief that his conduct was lawful — particularly when we are dealing in an area of international security concerns, and when the authorization is thought to come from the President himself.
Of course communications from associates or even subordinates would also be relevant if they bear on the defendant’s state of mind regarding the lawfulness of a given action. It is only incidental that this case arises in the context of a superior communicating with a subordinate. Nor is the issue unique to government. An individual working in a corporation, a union, or even a private law firm charged with a crime under which the government must prove knowledge of unlawfulness would be entitled to put in evidence communications from others in the institution that rebutted the contention that he was aware his conduct was unlawful. Communications from a superior might be given greater weight *886by a jury than, say a subordinate or equal but that would be because of the natural assumption that a superior knows more and, therefore, the defendant might be thought to more likely rely upon the superi- or’s view, not because the superior’s status entitles him or her to direct the subordinate to violate the law. Here, however, since we are concerned with an internal regulation concerning part of the White House staff, it is quite possible that North could have believed (even reasonably) that the President’s direction, specific or implicit, overrode the regulation. In this case then the President’s status as it bears on Count 9 is relevant. In particular, we think that the emphasized passages of the instructions quoted above were all prejudicial to North on this point. The requirement that North “reasonably believed the order was legally proper” was improper as it relates to Count 9, which, we repeat, both parties agree requires a jury determination that North knew he was acting unlawfully. When that is the nature of the intent required for conviction, the jury by definition must measure the defendant’s intent by a subjective standard. See United States v. Rhone, 864 F.2d 832, 835 (D.C.Cir.1989); United States v. Aitken, 755 F.2d 188 (1st Cir.1985). Thus, even an unreasonable belief that one’s conduct was not unlawful would seem properly to preclude conviction for a crime requiring knowledge of unlawfulness. See Liparota v. United States, 471 U.S. 419, 425 n. 9, 105 S.Ct. 2084, 2088 n. 9, 85 L.Ed.2d 434 (1985). The dissent maintains that a conviction is appropriate under section 2071(b) if the defendant “lacks a reasonable belief that his actions are not unlawful.” Wald Dissent at 929. Assuming for the moment that there is such a reasonableness requirement, the dissent’s articulation would entirely reverse the burden of proof on the state-of-mind requirement for this statute. It is the prosecution that must prove, beyond a reasonable doubt, that the defendant knew he was acting unlawfully (or, arguendo, that he lacked a reasonable belief that he was not acting unlawfully). We realize that this last clause is a double negative, but the change in wording makes a real difference: if North had no belief at all about the lawfulness vel non of his actions, or if he was uncertain, then the proper result is acquittal. Knowledge of unlawfulness means just that; it does not mean lacking the knowledge (or reasonable belief) that the conduct was legal.
Indeed, the whole issue raised by the dissent — that there is a requirement that the defendant’s belief that he was not acting unlawfully be reasonable — is a red herring. The District Court instructed the jury that “[f]or [Count 9], the defendant must have known his conduct was unlawful.” JA at 649 (emphasis' supplied). For purposes of this appeal, that should be the end of the matter.16 The dissent may well be correct that “the consensus is overwhelming that a defendant’s mistake of law must be reasonable to be exculpatory.” Wald Dissent at 930; United States v. Aguilar, 883 F.2d 662, 674-75 nn. 4 & 5 (9th Cir.1989) (criticizing Rhone). But we are not dealing here with the mere negation of specific intent; rather, we are dealing with a statute that indisputably (at least as between the parties) requires subjective knowledge of unlawfulness for conviction. None of the cases cited by the dissent involved statutes that require knowledge of unlawfulness for conviction.17 We also note that statutes requiring actual knowledge of unlawfulness for conviction are rare, making all but irrelevant the dissent’s exaggerated concern about defendants being exculpated for “bizarre and incredible mistakes of law.” Wald Dissent at 930. The obvious answer to this fear is that if the defendant’s belief *887in the lawfulness of his behavior is indeed incredible, then the jury will not credit it, and he will not be exculpated.18 In any event, even if we adopted the reasonableness limitation, it would not affect our decision on Count 9. We surely could not hold that it is unreasonable as a matter of law to believe that one’s superiors in the NSC, including the National Security Advisor himself, could authorize the destruction of internal NSC documents, especially when only an NSC regulation prohibits their destruction in the first place. This last point is critical because it makes it all the more plausible that the jury would credit North’s claim that he did not think he was acting unlawfully. Thus, the jury should have been able to consider the evidence of authorization in the record that was excluded by the District Court’s instructions even if it had been determining whether North reasonably believed his conduct was not unlawful.
Equally damaging was the instruction not to consider the evidence of authorization unless North was given “clear, direct instructions to act at a given time in a given way.” That instruction alone could very well have stopped the jury from considering any of the authorization evidence in the record. That evidence included North’s testimony that Casey told him “to get the operation in Central America cleaned up,” Tr. at 7023, 7029, and “to get rid of things that weren’t necessary.” Tr. at 7553. North also testified that, in North’s presence, Poindexter personally destroyed a Presidential Finding approving a shipment of HAWK missiles to Iran in 1985. Furthermore, McFarlane sent North a note on November 8,1986 stating that he hoped “someone was purging the NSA traffic files on [a matter relating to the Iranian arms shipment].” Tr. at 4781. Finally, with respect to certain altered documents concerning aid to the Contras, North testified that McFarlane told him to “fix these documents so that they are consistent with what we have basically told the Congress.” Tr. at 6903. All of that testimony was within the scope of what the jury should have been able to consider in its deliberations on Count 9, but none of it meets the District Court’s requirement that there be “clear, direct instructions to act at a given time in a given way." Not even the IC disputes this. See Brief for Appel-lee at 35-36 (Casey’s “general directive” was “vague, informal and inexact.” “McFarlane did not actually instruct North at that time to alter any documents.” “North did not offer evidence that he was specifically instructed ... ”).19
Finally, we think the related instructions that the jury could consider authorization only “if no alternative was available to [North] to comply with the order by other lawful means,” and that the authorization evidence could not be considered if “an authorization can be satisfied by two different courses of action, one clearly legal and one illegal or of dubious legality, and a person chooses the illegal or dubious course when other, legal action would comply,” were prejudicial. These instructions improperly direct the jury’s deliberations away from North’s state of mind and instead focus them on the objec*888tive question of whether the destruction of documents violated the executive branch regulation. The dissent argues that these instructions were harmless because North had to destroy, alter, and remove documents in order to comply with his instructions and there were no alternative lawful means to do that because to do so would violate the executive branch regulation. See Wald Dissent at 930. Obviously, these instructions require the jury to determine whether a course of action is legal, illegal, or of dubious legality (whatever that means) without considering the evidence of authorization. In this context, as the question here is whether that authorization made the defendant believe (reasonably or unreasonably) that he was acting lawfully notwithstanding the regulation, this limitation is prejudicial. If he did so believe, then his course was not illegal or even dubious. The District Court’s instruction in effect makes violation of the regulation a per se violation of the statute without regard to the defendant’s belief that his authorization from the highest echelons of the executive branch could trump a regulation about document control.
Our dissenting colleague appears to agree that evidence of authorization is relevant to Count 9 on the issue of North’s knowledge of unlawfulness. Nevertheless, the dissent defends all of the District Judge’s strictures on the jury’s consideration of that evidence. In effect, the dissent argues that one must make out a full-blown authorization defense consisting of reasonable reliance on a superior’s assurance that the desired action is legal — based on that superior’s interpretation of the law — before the evidence of what the superior told you can even be considered by the jury.20 Where, as here, the statute requires the jury to find subjective knowledge of unlawfulness, that view cannot prevail. Evidence of what one’s superiors say and do, even if they do not explicitly assure one that the conduct is legal, might be crucial in establishing the defendant's belief that his conduct was not unlawful. This does not mean, as the dissent suggests, that a defendant charged with this crime or a similar one can gain acquittal simply by pleading he was “following orders.” Those orders or directions or communications permit the jury to acquit only if the jurors find that the defendant did not know his conduct was illegal. Because the District Court’s instruction on authorization precluded the jury from fully considering whether North’s claim of authorization rebutted the prosecution’s burden of showing North’s knowledge that his behavior was unlawful, and because it is impossible to say that the error was harmless — authorization being the core defense — North’s conviction on Count 9 must be reversed.
IV. The Reagan Subpoena
North contends that his convictions on Counts 6 and 9 should be reversed because the District Court erroneously quashed his subpoena to former President Ronald Reagan. Finding that Mr. Reagan’s testimony would not have added anything material to North’s defense to Counts 6 and 9, we decline to reverse North’s convictions on this ground.
A. Background
Prior to his trial, North served then-President Reagan with a subpoena ad testifi-candum. Mr. Reagan, represented by the Attorney General, moved to quash the subpoena. The District Court held the matter in abeyance until trial was underway, when North again asked the court to require Mr. Reagan’s appearance. The court ordered North to file “under seal, ex parte a succinct particularized statement of facts defendant desires to elicit from President Reagan.” United States v. North, Cr.No. 88-0080-02, 1989 WL 57512 (D.D.C. Mar. 27, 1989) (order). North identified thirteen subjects on which he expected to elicit favorable testimony from Mr. Reagan, including the fact that “between November 7 and *889November 25, 1986, Mr. Reagan approved of and participated in efforts to withhold many aspects of the [Iran] initiative from Congress and the public.” JA at 3237 (sealed appendix). After examining North’s proffer along with Mr. Reagan’s written responses to grand jury interrogatories and portions of Mr. Reagan’s personal diary, the court concluded that “[t]here has been no showing that President Reagan’s appearance is necessary to assure Lt. Col. North a fair trial.” United States v. North, 713 F.Supp. 1448, 1450 (D.D.C.1989).
B. Legal Standard
The Sixth Amendment guarantees a defendant the right “to have compulsory process for obtaining witnesses in his favor.” U.S. ConstAmend. VI. “Few rights are more fundamental” than this one, Chambers v. Mississippi, 410 U.S. 284, 302, 93 S.Ct. 1038, 1049, 35 L.Ed.2d 297 (1973), for it is “in plain terms the right to present a defense,” Washington v. Texas, 388 U.S. 14, 19, 87 S.Ct. 1920, 1923, 18 L.Ed.2d 1019 (1967). In practice, however, this right is subject to several limitations. See, e.g., United States v. Thornton, 733 F.2d 121, 125 (D.C.Cir.1984) (right to compulsory process does not compel witness to waive Fifth Amendment privilege). Most important in the instant context is the requirement that the witnesses’ testimony be “material and favorable to [the] defense.” United States v. Valenzuela-Bernal, 458 U.S. 858, 867, 102 S.Ct. 3440, 3446, 73 L.Ed.2d 1193 (1982). See also Washington, 388 U.S. at 23, 87 S.Ct. at 1925 (wit nesses must be “relevant and material” to defense). The primary concern on review is whether the defendant suffers actual prejudice from his inability to obtain compulsory process. See Valenzuela-Bernal, 458 U.S. at 869, 102 S.Ct. at 3447.
C. Application
In Part III(A), supra at 878-81, we dismiss North’s contention that he was entitled to an instruction charging the jury to return a verdict of not guilty if it found the necessary elements of an “authorization defense.” As a result, we need not consider whether Mr. Reagan’s testimony was necessary for North to make out such a defense. Rather, our inquiry is limited to whether Mr. Reagan would have presented to the jury evidence relevant and material to North’s claim that he lacked the criminal intent defined by the statutes under which he was convicted.
1. Count 6
North’s argument on appeal as to his need for Mr. Reagan’s testimony focuses on his conviction under Count 6 for obstructing pending congressional inquiries as an aider and abettor, in violation of 18 U.S.C. §§ 1505 and 2. Brief for Appellant at 45-46. North asserts that Mr. Reagan would have corroborated his defense by testifying that he authorized William Casey and John Poindexter to withhold information from Congress concerning the 1985 sales of HAWK missiles to Iran. Assuming that presidential authorization would have exonerated Casey and Poindexter from the “corrupt” intent required by the statute, North contends that his conviction as an aider and abettor, stemming from his role in preparing a false chronology to be used by Casey and/or Poindexter when they testified before congressional committees on November 21, 1986, and in destroying, altering, and concealing official NSC records and papers concerning arms sales to Iran and efforts to aid the Contras, logically would have fallen as well. North points out that only Mr. Reagan could have told the jury whether he had authorized Poindexter and Casey to conceal the 1985 HAWK sales from Congress.
We have said in Part 111(B)(1), supra at 881-884, that a person who “corruptly” intends to obstruct a pending investigation has the requisite criminal intent under 18 U.S.C. § 1505. The person need not know that his actions are unlawful in order to violate the statute. Thus, evidence of authorization, presumably intended to demonstrate that the defendant believed his actions were lawful, would not exculpate a defendant who admitted performing actions that impeded or obstructed a congressional investigation in a corrupt manner. *890By extension, neither principals who corruptly obstructed Congress nor their aiders and abettors would be exculpated by evidence that the principals’ actions were authorized by their superior.21
The jury, of course, could not have convicted North of aiding and abetting unless Poindexter or Casey had acted as a principal in corruptly obstructing Congress. And, correlatively, if Casey or Poindexter had intended corruptly to obstruct Congress, evidence of a putative presidential authorization would be irrelevant to their criminal intent under 18 U.S.C. § 1505, as well as to North’s under 18 U.S.C. § 2. North’s testimony at trial provided the jury with substantial evidence of Poindexter’s and Casey’s endeavor to destroy or suppress evidence relevant to Congress’s ongoing investigation. North testified that at a meeting held in Poindexter’s office and attended by Poindexter, North proposed false and obfuscatory changes in the chronology that was supposed to accompany Casey’s congressional testimony the following day. Tr. at 7631.22 North further recalled that Casey also instructed him specifically to destroy the Contra operating fund ledger and more generally to “start cleaning things up, to get rid of things that weren’t necessary.” Tr. at 7553. North also saw Poindexter destroy a Finding by President Reagan approving the 1985 HAWK shipment to Iran. Tr. at 7612-13.
We explained in Part 111(B)(1), supra, that the jury was authorized to interpret the “corrupt[]” intent requirement in 18 U.S.C. § 1505 according to the word’s common meaning. See supra at 881. Provided that the jury was convinced beyond a reasonable doubt that Casey’s and Poindex-ter’s actions in preparing the false chronology and altering and destroying official documents were intentional endeavors corruptly to influence an ongoing congressional inquiry, and that North aided and abetted Casey and Poindexter with the same corrupt intent, the jury was duty-bound to find North guilty of aiding and abetting the corrupt obstruction of a pending congressional inquiry. In those circumstances, whether or not Casey or Poindexter — or North himself — was following President Reagan’s orders is immaterial to North’s defense. See supra at 884. Nor would Casey’s and Poindexter’s motives, however laudable, exculpate their otherwise corrupt endeavor to obstruct an ongoing congressional investigation. See supra at 883— 884.
Furthermore, the available evidence concerning Mr. Reagan’s involvement in Casey’s and Poindexter’s concealment is entirely unhelpful to North. In his responses to the IC’s interrogatories, Mr. Reagan flatly denied authorizing any of Casey’s statements to Congress concerning the Iran arms sales; indeed, he reported receiving his only advance knowledge of Casey’s testimony on the eve of that testimony, when Secretary of State Shultz informed him of discrepancies between his own recollections and what he understood would be Casey’s testimony the following day. Cf. Silberman Dissent at 950 n. 26.23 Nor do Mr. Reagan’s responses provide any sustenance for North’s belief that Mr. Reagan concealed the HAWK shipments during a meeting with congressional leaders in early November 1986 and thus authorized his subordinates to act similarly; Mr. Reagan’s answers imply that he had no recollection in November 1986 of arms sales that took place a year earlier. Cf. Brief for Appellant at 45 n. 77.
*8912. Count 9
Count 9 charged North with concealing, mutilating, obliterating, falsifying and destroying official documents. North never claims that Mr. Reagan authorized any such conduct; at most, North contends that Mr. Reagan indirectly encouraged him to withhold information from Congress. See JA at 3237 (sealed appendix). As we indicate in Part 111(B)(2) of our opinion, conviction on Count 9 required the jury to believe that North knew he was violating the law. Absent any proffer by North that Mr. Reagan ever approved the destruction, alteration, or concealment of official NSC documents, the District Court fairly concluded that any evidence of authorization provided by Mr. Reagan would have had no bearing on whether North considered his activities lawful. Even if, as North claims, Mr. Reagan indicated to his subordinates that he did not want the Iran and Contra initiatives disclosed, North presents no evidence that the President authorized his subordinates to employ the means charged in Count 9. In light of the NSC’s internal regulation severely restricting the removal and destruction of official documents, see National Security Council Administrative Manual 33 (Oct.1984) [Supplemental Appendix at 105], the trial judge was fully justified in refusing to credit North’s contention that Mr. Reagan’s comments about nondisclosure were meant to authorize the destruction, alteration, and concealment of official documents.24
3. Corroborative Effect of Mr. Reagan’s Testimony
In considering the materiality of the evidence North hoped to elicit from Mr. Reagan, the District Court inquired only into “whether or not Mr. Reagan while President, directly or indirectly, authorized Lt. Col. North to take any of the actions” underlying his indictment. United States v. North, 713 F.Supp. at 1450. North attacks this standard as not taking into consideration the corroborative force of Mr. Reagan’s testimony to North’s defense. Clearly, corroborative evidence can be material to a defense. See United States v. Detrich, 865 F.2d 17, 22 (2d Cir.1988). But the record in this case contains ample evidence for the jury to have found that Casey, Poindexter, and North himself intended corruptly to obstruct an ongoing congressional inquiry, and no reason whatsoever to suspect that Mr. Reagan would have offered any testimony indicating that he authorized concealment of the 1985 *892HAWK shipment from Congress. The record also contains no evidence whatsoever that Mr. Reagan ever suggested that North alter, destroy, or conceal official documents. Consequently, the District Judge’s narrow formulation of the standard for granting North’s subpoena amounted to at worst harmless error.25
D. Conclusion
There is no indication that Mr. Reagan would have provided evidence material or favorable to North with respect to Counts 6 and 9.26 Accordingly, we decline to reverse his conviction on the grounds of the denial of the Reagan subpoena.
V. Pending Inquiry Instruction
North’s conviction on Count 6 for aiding and abetting the obstruction of a congressional inquiry required the IC to prove that an “inquiry or investigation is being had by either House, or any committee of either House or any joint Committee of the Congress ...” 18 U.S.C. § 1505 (emphasis supplied); see also JA at 634 (jury instructions) (evidence must establish that congressional inquiry “underway” in November 1986). North contends that his Fifth Amendment right to due process and his Sixth Amendment right to a jury verdict were violated when the District Judge instructed the jury
as a matter of law that congressional inquiries were pending and that Congress was authorized to inquire into arms sales [to Iran] and Contra assistance, both of which were relevant and material issues, [tl] You need only deliberate regarding the other three elements [of 18 U.S.C. § 1505]_
JA at 635. North’s counsel objected to the finding “that as a matter of law” congressional inquiries were underway in November 1986 on the grounds that “what this permits the jury to do is to find there was an obstruction of an investigation concerning a matter that was in fact not pending at that time_” Tr. 8499.
We agree that the District Court erred by removing this element of the offense from the jury’s province. Indeed, in their proposed jury instructions both North and the IC requested that the jury decide whether the inquiry was pending. See JA at 2434, 2468-70. We do not, however, believe that the judge’s charge deprived North of a fair trial.
The Supreme Court has “repeatedly reaffirmed the principle that an otherwise valid conviction should not be set aside if the reviewing court may confidently say, on the whole record, that the constitutional error was harmless beyond a reasonable doubt.” Delaware v. Van Arsdall, 475 U.S. 673, 681, 106 S.Ct. 1431, 1436, 89 L.Ed.2d 674 (1986). Thus, while some constitutional errors, such as the complete denial of the right to counsel, Gideon v. Wainwright, 372 U.S. 335, 83 S.Ct. 792, 9 L.Ed.2d 799 (1963), or adjudication by a biased judge, Turney v. Ohio, 273 U.S. 510, 47 S.Ct. 437, 71 L.Ed. 749 (1927), are so egregious as to require reversal “without regard to the facts or circumstances of the particular case,” Van Arsdall, 475 U.S. at 681, 106 S.Ct. at 1436 constitutional errors that occur at “a trial, at which the defendant, represented by counsel, may present evidence and argument before an impartial judge and jury” are properly subjected to a harmless error analysis. Rose v. Clark, 478 U.S. 570, 578, 106 S.Ct. 3101, 3106, 92 L.Ed.2d 460 (1986). Provided that “beyond a reasonable doubt ... the error complained of did not contribute to the verdict obtained,” Chapman v. California, 386 U.S. 18, 24, 87 S.Ct. 824, 828, 17 L.Ed.2d *893705 (1967), the error is not grounds for reversal.
The Supreme Court has never held that the trial judge’s determination of one of the elements of a crime is per se reversible error. Cf. Silberman Dissent at 956-957. Indeed, in Carella v. California, — U.S. -, 109 S.Ct. 2419, 105 L.Ed.2d 218 (1989), the Court remanded for a harmless error inquiry even though the jury instructions at issue “relieved the State of its burden of ... proving by evidence every essential element of Carella’s crime beyond a reasonable doubt.” Id. 109 S.Ct. at 2420. Four Justices concurring in the judgment placed the harmless error remand in context, explaining, inter alia, that “an instruction establishing a conclusive presumption with regard to an element of the crime that the defendant in any case admitted” was properly subject to harmless error analysis. Id. at 2423 (Scalia, J., concurring in the judgment). The mere fact that an error “deprives the jury of its factfind-ing role” is not per se grounds for reversal, id., and is subject to harmless error analysis when no rational jury could find the other elements of the offense without finding the fact presumed, see id. at 2421 (per curiam); id. at 2423 (Scalia, J., concurring in the judgment).
We have no doubt that a harmless error analysis is appropriate here. Although the District Judge’s instruction took one narrow determination away from the jury, the error neither “aborted the basic trial process” nor “denied it altogether.” Rose, 478 U.S. at 578 n. 6, 106 S.Ct. at 3106 n. 6. Since the jury had to find all of the other elements of a violation of 18 U.S.C. § 1505 — whether North knew of the pending inquiries, whether he endeavored to obstruct them, and whether he did so with requisite criminal intent, see JA at 635 — the instruction imposed no conclusive presumption of guilt, see Carella, 109 S.Ct. at 2421, and left the jury, rather than the judge, as the ultimate arbiter of whether North violated 18 U.S.C. § 1505, see Rose, 478 U.S. at 578, 106 S.Ct. at 3106.27 In these circumstances, we are not concerned that the trial court was “directpng] a verdict for the prosecution in a criminal trial by jury” — a matter of concern to the Supreme Court in a situation where the “wrong entity” actually adjudged the defendant’s guilt, id. Cf. Silberman Dissent at 956.
There can be little doubt that this instruction did not deprive North of a fair trial on the charge of corruptly obstructing Congress. North conceded at trial that he substituted the acronym “USG” [United States Government] for “CIA” and “NSC” throughout the chronology that was supposed to accompany Casey’s and/or Poindexter’s testimony before Congress — a change that North admitted left the chronology as a “false statement.” Tr. 7631. While preparing the false chronology, “[i]t [was] [North’s] understanding that Director Casey was going to testify, and Admiral Poindexter, I think I knew at that point, was going to brief [Congress].... ” Tr. at 7632-33. North further testified that while he did not “recall people talking about specifically that [the false chronology] is going to be used at this meeting of the Congress or that meeting of the Congress,” he “apparently ... had a card that showed the times later on the next day” for Casey’s and Poindexter’s appearances before Congress. Tr. at 7635. North also readily admitted at trial that he altered, destroyed, and concealed official documents in this same time frame. See Tr. at 6907 (North “had the documents pulled from the files and altered them consistent with what [McFarlane] had earlier asked me to do”); Tr. at 7138-39 (North’s testimony about destruction of Contra operating fund ledger on Casey’s instruction); Tr. at 7109-13 (North’s testimony about removal of official documents after being fired to “protect” himself). It is clear from North’s own trial testimony, therefore, not only that congressional inquiries were in fact pending in November 1986, but also *894that he himself realized they were pending at that time.
Carella's test for harmless error is that “no rational jury could find the predicate acts but fail to find the fact presumed.” 109 S.Ct. at 2421 (citing Rose ).28 Similarly, in light of North’s own testimony, no rational jury could find that North knew of the pending congressional investigation, endeavored to obstruct it, and did so with specific corrupt intent without concomitantly finding that the investigation was pending in the first place.29 See also id. at 2423 (Scalia, J., concurring in the judgment) (“When the predicate facts relied upon in the instruction, or other facts necessarily found by the jury, are so closely related to the ultimate fact to be presumed that no rational jury could find those facts without also finding that ultimate fact, making those findings is functionally equivalent to finding the element required to be presumed” and the error is harmless.).30
In light of North’s admissions at trial, we believe the judge’s error in his instruction on Count 6 properly comes under a harmless error analysis that reveals no prejudice to North. We therefore affirm North’s conviction on Count 6.
VI. Closing Argument
North contends that certain comments made by the IC to the jury during closing arguments were improper and mandate reversal of his convictions. In particular, North complains about the IC’s comparison of his conduct to Adolf Hitler’s, and about the IC’s statement that Richard Secord and Albert Hakim made a “killing” from arms sales to Iran and the Contras, despite the absence of any evidence in the record concerning the amount of their profits. Although both of the prosecutor’s remarks were clearly improper, we find that neither was sufficiently prejudicial to North as to warrant the reversal of any or all of his convictions.
A. Legal Standard
A prosecutor may not make “statements calculated to arouse the passions or prejudices of the jury,” United States v. Monaghan, 741 F.2d 1434, 1440 (D.C.Cir.1984), cert. denied, 470 U.S. 1085, 105 S.Ct. 1847, 85 L.Ed.2d 146 (1985), or “statements of fact to the jury not supported by proper evidence introduced during trial,” United States v. Perholtz, 842 *895F.2d 343, 360 (D.C.Cir.) (quoting Gaither v. United States, 413 F.2d 1061, 1079 (D.C.Cir.1969)), cert. denied, 488 U.S. 821, 109 S.Ct. 65, 102 L.Ed.2d 42 (1988). When an objection is timely made, such remarks, while improper, are cause for reversal only if they “sufficiently prejudiced” the defendant. United States v. Fowler, 608 F.2d 2, 12 (D.C.Cir.1979) (quoting Gaither, 413 F.2d at 1079). We have generally looked to three factors in determining whether improper remarks by the prosecutor sufficiently prejudiced a defendant: “the closeness of the case, the centrality of the issue affected by the error, and the steps taken to mitigate the effects of the error.” Fowler, 608 F.2d at 12 (quoting Gaither, 413 F.2d at 1079). We have also framed the test for prejudice in terms of the severity of the prosecutor’s misconduct, the measures adopted to cure the misconduct, and the certainty of conviction absent the improper remarks. Perholtz, 842 F.2d at 361; Monaghan, 741 F.2d at 1443. “[I]n assessing the effect a prosecutor’s remark would have had on a jury,” however, we seek to avoid an overly mechanistic application of these criteria by according “due respect” to “the jurors’ common sense and discrimination.” Monaghan, 741 F.2d at 1440.
B. Application
1. Reference to Hitler31
The IC stated during closing argument that:
So far in this drama in August and September of 1985, North and McFarlane are following Adolf Hitler’s old strategy. He was the one who said, the victor will never be asked if he told the truth. And the idea here was if the lies work, Congress will stop asking questions.
Tr. at 8011. Unquestionably inflammatory, the reference to Hitler reflected remarkably poor judgment by the IC. Nonetheless, in response to North’s timely motion for a mistrial, the District Court pointed out that “defendant’s ... counsel took full advantage of the reference in his effective response before the jury.” United States v. North, Cr. No. 88-0080-02, 1989 WL 57493 (D.D.C. May 5, 1989) (order) [hereafter “May 5 Order”].32 Clearly, the District Judge is better situated than we are to assess the impact of both sides’ hyperbole upon the jury. In light of defense counsel’s forceful reply to the IC’s ill-chosen remark, we have no reason to disagree with the District Court’s perception that the IC’s statement caused no substantial prejudice to North. To suspect that the reference to Hitler swayed the jury on a close and critical issue would underestimate the common sense that we properly attribute to the jury. We therefore decline to reverse any of North’s convictions on this ground.
2. Reference to Secord’s and Hakim’s “Killing”
During the course of the trial, the IC elicited testimony from Willard Zucker that Zucker had distributed “profits” from certain bank accounts to Albert Hakim and Richard Secord. Tr. at 5218. The IC also sought to introduce evidence that would have established the amount of profits Se-cord and Hakim had made from arms sales to Iran. North objected, claiming that the amount of profits was immaterial to the charges against him. Tr. at 5233. In an ensuing bench conference, the IC explained *896that the evidence was crucial to establishing North’s motive in accepting a security fence from Secord in return for official acts, as charged in Count 10. By showing that Secord had made large profits through the business channeled to him by North, the IC apparently hoped to persuade the jury that North accepted the fence as an illegal gratuity, rather than as a gift from a solicitous friend seeking to protect North’s family. Tr. at 5234. As the IC told the trial judge, “[t]he amount [of profits] certainly gives a powerful motive on both sides.” Tr. at 5234-35.
The District Judge initially suggested that “the way to deal with it is to simply say were those amounts substantial or something of that kind and go on.” Tr. at 5235. North’s counsel objected to that proposal, intimating- that if the IC introduced any evidence about the amount of profits, North would be entitled to respond by explaining Secord’s and Hakim’s businesses in detail. The District Judge agreed and told the IC that “if you want to put some figure in terms of small or large profits, if you want to call it profits,” then North would be permitted to explore “[a]ll the other businesses that [Secord and Hakim] do.” Tr. at 5237. Faced with that prospect, the prosecutor said, “We don’t want to do that.” Id. He then added, “I think we’ll leave it alone.” Tr. at 5239. Nevertheless, the IC did raise the issue of the amount of Secord’s and Hakim’s profits in the closing argument. He stated:
To understand the security fence charge I think you need to consider the testimony about North’s relationship with Se-cord and Hakim. Secord and Hakim were making a killing, a killing. Millions in Contra arms sales, millions coming in from the Iranian arms sales. All from the business that Oliver North, the government official, the action officer of the NSC, the person who could say this is the White House calling, all from the business that he brought to them.... [North knew] that Secord and Hakim were taking a fair and reasonable profit but he didn’t know what they considered a fair and reasonable profit. Would you send ten million or 20 million or 14 million or five million or even $5 to somebody who is going to take a fair and reasonable profit without talking to them about what a fair and reasonable profit was? Secord and Hakim were making a killing....
Tr. at 8038-40. Although North moved for a mistrial on the basis of that statement, the District Judge denied the motion on the grounds that “the use of the word ‘killing’ was mere characterization.” See May 5 Order.
In- light of the prosecutor’s agreement not to introduce evidence of the size of Secord’s and Hakim’s profits, his description of their profits as a “killing” or as “millions” was improper. Whether or not those references were slips of the tongue in the heat of oral argument, they amounted to “statements of fact ... not supported by proper evidence introduced during trial.” Perholtz, 842 F.2d at 360. We must therefore determine whether the remarks sufficiently prejudiced North to require reversal of his conviction on Count 10 — the only conviction count implicated by the prosecutor’s misstatement. As we consider the various factors that this Court has identified as relevant to the prejudicial effect of prosecutorial misconduct, see id. at 361; Fowler, 608 F.2d at 12, we focus on three criteria: the magnitude of the potential prejudice, the magnitude of the prosecutor’s error, and the curative measures adopted by the trial judge.
a. Magnitude of Potential Prejudice
To convict North under Count 10, the jury had to find only that he accepted the security system “for or because of” an official act. 18 U.S.C. § 201(c)(l)(B)(1988). The evidence that North channeled a substantial amount of arms business to Secord and Hakim is undisputed; North himself testified that he knew Secord sold the Contras approximately $11 million worth of weapons and made a sufficient profit on those transactions so as to receive “fair and just” and “reasonable” compensation. Tr. at 7181, 7307. Even absent evidence as to the size of Secord’s and Hakim's profits, the jury had ample grounds to infer that *897Secord gave North the security fence as a gratuity in exchange for referring to him millions of dollars of arms business. As this inference provided sufficient basis for conviction, the jury’s decision to convict could not have turned critically on the prosecutor’s improper description of the size of Secord’s and Hakim’s profits. In light of the record evidence of the substantial links between North and Secord and Hakim, the reference to the size of the profits could have had only limited corroborative effect on the jury’s perception of North’s motive in accepting the fence. The prosecutor’s comments, therefore, were at worst minimally prejudicial.
b. Magnitude of Prosecutorial Misconduct
Like other courts of appeal, we have traditionally been chary of reversing convictions solely on the grounds of a misstatement in a closing argument. See Monaghan, 741 F.2d at 1443 (affirming conviction because improper remarks confined to closing argument, rather than part of cumulative evidence that proceeding driven by passion and prejudice); see also United States v. Modica, 663 F.2d 1173, 1181 (2d Cir.1981) (upholding conviction despite several improper remarks by prosecutor during summation), cert. denied, 456 U.S. 989, 102 S.Ct. 2269, 73 L.Ed.2d 1284 (1982). Without other compelling factors, a single misstatement confined to a closing argument rarely amounts to severe misconduct. The Supreme Court has approved this approach, holding that absent “consistent and repeated misrepresentation” to influence a jury, “[ijsolated passages of a prosecutor’s argument, billed in advance to the jury as a matter of opinion not of evidence, do not reach the same proportions.” Donnelly v. DeChristoforo, 416 U.S. 637, 646, 94 S.Ct. 1868, 1873, 40 L.Ed.2d 431 (1974). By contrast, tainted closing arguments that follow on the heels of improper and indecorous prosecutorial conduct during trial are more likely to amount to the type of severe misconduct that justifies reversing a conviction. See Berger v. United States, 295 U.S. 78, 84-89, 55 S.Ct. 629, 631-33, 79 L.Ed. 1314 (1935).
c. Curative Measures
Our unwillingness to reverse a conviction has been particularly pronounced when the trial judge issues curative instructions. See Perholtz, 842 F.2d at 361 (citing precedent for proposition that “[cjourts have often emphasized the curative power of a trial court’s instructions”). Indeed, a former member of this Court declared that “it is the law, pure and simple, that jury instructions can sufficiently protect a defendant’s interest in being free from undue prejudice.” Id. (citing United States v. Daniels, 770 F.2d 1111, 1120 (D.C.Cir.1985) (Starr, J., concurring)). Here, Judge Gesell expressly addressed the role that closing arguments should play in the jury’s deliberations, and explicitly reminded the jurors that “the statements, opinion, and arguments of counsel are not evidence.” JA at 601. He stressed repeatedly that the jurors’ “recollection alone” is controlling as to “all aspects of the evidence.” JA at 602. The District Judge could not have more directly communicated to the jury the limited evidentiary value of closing arguments.
C. Conclusion
North does not make out any of the components of substantial prejudice resulting from the prosecutor’s closing argument. The District Court found that the reference to Hitler plainly was not prejudicial, and we have no reason to disagree. Furthermore, while a verdict of not guilty on Count 10 would not have been irrational, in light of North’s own testimony about the scope of Secord’s and Hakim’s arms dealings, it appears virtually certain that the jury would have convicted North on this Count in the absence of the prosecutor’s reference to the size of their profits. Finally, the prosecutor’s misconduct was at most marginal, limited to a few lines in a closing statement; and the trial judge offered clear curative instructions.33
*898This Court reverses a conviction on the grounds of a prosecutor’s summation in only the rarest and most prejudicial circumstances. See, e.g., United States v. Doe, 903 F.2d 16 (D.C.Cir.1990) (reversing conviction on grounds of prosecutor’s racially inflammatory summation). We have not reversed a conviction in over twenty years on the grounds of a prosecutor’s reference during closing argument to facts outside the record.34 Reversing North’s conviction for a single inappropriate remark of this nature in the prosecutor's closing argument is not only inconsistent with our past application of the substantial prejudice standard but would set a precedent requiring us to overturn virtually every conviction even marginally tainted by such a prosecutorial miscue. We therefore deny North’s appeal for reversal on this ground.
VIL CIPA Claims
North argues that the District Court’s application of the Classified Information Procedures Act, 18 U.S.C. App. (1988) (“CIPA”), violated his right to due process by compelling him to reveal to the IC before trial a 162-page summary of anticipated classified defense testimony, and by not imposing a reciprocal burden on the IC. Although the District Judge did not hew precisely to CIPA’s procedural outline, we believe that his balancing of the obligations imposed by CIPA on both parties does not warrant reversal of North’s conviction.
A. Statutory Framework
At issue here is the District Court’s application of CIPA sections 5 and 6. Section 5 requires the defense to notify the prosecution, before trial, of all classified information that the defense “reasonably expects to disclose or to cause the disclosure of” at trial. CIPA, 18 U.S.C. App. § 5(a). If the defendant fails to comply with section 5(a), the court may preclude his disclosure of classified information not properly noticed and may prohibit him from examining witnesses with respect to that information. Id. § 5(b).
Section 6 is the “heart” of CIPA. S.Rep.No. 823, 96th Cong., 2d Sess. 7, reprinted in 1980 U.S.Code Cong. & Admin. News 4294, 4300. Under section 6(a), the government may move for a hearing to determine, before further proceedings, the “use, relevance, or admissibility” of the classified information that the defense expects to disclose. CIPA, 18 U.S.C.App. § 6(a). Although section 6(a) does not specify that it is limited to classified information that the defense has noticed under section 5(a), the statutory structure and legislative history suggest that interpretation. S.Rep.No. 823, at 7, reprinted in 1980 U.S.Code Cong. & Admin.News at 4300 (“Once the Government learns that the defendant may disclose or cause to be disclosed classified information, it may move for a hearing.”). See United States v. Collins, 720 F.2d 1195, 1200 (11th Cir.1983) (similar interpretation).
Before a section 6(a) hearing, the government “shall provide the defendant with notice of the classified information that is at issue.” CIPA, 18 U.S.C. App. § 6(b)(1). This provision obligates the government, if it moves for a section 6 hearing, to notify the defense of those items in the defense’s section 5 submission whose disclosure it will contest in the section 6(a) hearing. The government meets this burden either by specifically identifying the classified information that it has already made available to the defense, or by generically describing the classified information that it has not yet provided. Id. In addition, at the defendant’s request, the court may order the prosecution to provide the defense with such details of the indictment “as are needed to give the defendant fair notice to prepare for the hearing.” Id. § 6(b)(2).
*899If the government’s motion for a section 6(a) hearing is timely filed, the court must determine the use, relevance, and admissibility of the classified information noticed by the defense before further proceedings ensue. Hearings are held in camera if the Attorney General certifies to the court that a public proceeding “may result in the disclosure of classified information.” Id. § 6(a). The court must set forth in writing “the basis for its determination” as to each item of classified information at issue. Id. If, after an in camera hearing, the court determines that the classified information in question should not be disclosed, the hearing record is sealed. The defendant may seek reconsideration before or during trial of the court’s determination not to disclose the classified information. Id. § 6(d).
If the court authorizes disclosure of specific classified information by the defendant, the prosecution may move the court to order, in lieu of that classified information, either an admission of relevant facts or a summary of the information. Id. § 6(c)(1). The court must grant the government’s motion if it finds that the admission or summary will leave the defendant in substantially the same position as would disclosure. Id. In connection with its motion under section 6(c)(1), the government may submit to the court an affidavit from the Attorney General explaining the basis of the government’s classification and certifying that disclosing the classified information requested by the defendant would damage United States national security. Id. § 6(c)(2).
If the court denies the government’s motion under section 6(c), and the government files an affidavit objecting to the defendant’s release of classified information, the court “shall order that the defendant not disclose or cause the disclosure of” that information. Id. § 6(e)(1). At that point, however, the court must either dismiss the indictment or, if it determines that such a drastic step would not serve the “interests of justice,” take more limited measures. Id. § 6(e)(2). These remedies do not take effect until the government has had an opportunity for interlocutory appeal and, thereafter, a chance to withdraw its objection to the defense’s use of classified information. Id.
Finally, if the court determines, pursuant to a section 6(a) hearing, that the defense may disclose classified information at trial or in a pretrial proceeding, “the court shall, unless the interests of fairness do not so require, order the United States to provide the defendant with the information it expects to use to rebut the classified information.” Id. § 6(f). The court may impose a continuing duty on the government to disclose such rebuttal information. If the government does not comply with its obligation under section 6(f), the court may prohibit both its use of unrevealed classified information and its examination of witnesses with respect to that information. Id.
B. Course of Events
In June 1988, the District Judge concluded that “strict application” of CIPA’s complex procedure would be “impossible to accomplish consistent with a fair and expeditious resolution” of North’s trial because of the enormous amount of classified information directly relevant to the case, including the myriad classified documents written by or sent to North. United States v. Poindexter, 698 F.Supp. 316, 319 (D.D.C.1988). The District Judge proposed, therefore, to focus on fulfilling CIPA’s overall goal of “mak[ing] the defendant whole.” To that end, Judge Gesell directed North to file a section 5 notice by July 11, 1988, preceded by an in camera, ex parte hearing,35 at which North would inform the court of the relevance to his defense of key classified documents and the court would consider alternatives to full disclosure. Id. at 321.36 *900In the same order, the District Court explained that it would neither monitor defense counsel’s opening and closing statements, nor subject defense testimony at trial to advance scrutiny. Id. at 322. On July 8, in response to concerns voiced by North at the ex parte hearing regarding IC redactions and substitutions, the District Court postponed North’s section 5 submission until August 1 to allow him to notice the redacted material that he required. The District Court also ordered the IC to release further specific information that North requested. United States v. North, 698 F.Supp. 322, 325 (D.D.C.1988).37
The CIPA issues were not resolved as the court had anticipated, however. Judge Gesell rejected North’s August 1 section 5 submission as “wholly insufficient” because it lacked “necessary particularization” as to the relevance and materiality of the documents noticed. Nonetheless, the District Judge invited a new section 5 submission by November 14, 1988, without prejudice to North. United States v. North, Cr. No. 88-0080-02, 1988 WL 148514 (D.D.C. Aug. 5, 1988) (order). On October 31, the District Court denied North’s motion, made pursuant to CIPA § 6(b)(2), for the IC to provide further details about the indictment in order to assist North in preparing his new section 5 notice. CIPA’s structure, according to the District Judge, required North’s section 5 submission to precede section 6(b)(2) notice by the IC. United States v. North, Cr. No. 88-0080-02, 1988 WL 148504 (D.D.C. Oct. 31, 1988) (order).
North’s second section 5 submission again failed to break the logjam. The District Court found North’s November 14 filing unacceptable because it sought disclosure of large amounts of classified material “which under no conceivable version of a defense could have any utility whatsoever.” United States v. North, 708 F.Supp. 389, 395 (D.D.C.1988). Consequently, the District Judge precluded North from using during trial any of the classified information in the documents noticed on November 14; he did, however, allow North until January 3, 1989 to identify 300 documents containing classified information, roughly the same number as the government expected to use in its case-in-chief. Under this plan, North would explain the relevance and materiality of disputed classified items at an in camera hearing. Id. at 398-99.38
Meanwhile, beginning on November 30, the District Court conducted in camera hearings pursuant to CIPA § 6 to consider redactions in the classified documents that the IC intended to offer in his case-in-chief. Although North opposed nearly all proposed redactions and substitutions in those documents, the District Judge approved a series of edits in order to assure that the trial could be kept open to the public. United States v. North, Cr. No. 88-0080-02, 1988 WL 148481 (D.D.C. Dec. 12, 1988) (memorandum and order).39
*901On December 19, 1988, pursuant to the court order of November 23, see supra note 38, North filed ex parte and in camera a 162-page “narrative summary” of the classified information that he expected to use or elicit at trial. See United States v. North, 708 F.Supp. 399, 400 (D.D.C. 1988). Four days later, the District Court ordered North to transmit this document to the prosecutor because it contained relevant and material information that, at least in part, had not previously been brought to the IC’s attention, id. at 401; a panel of this Court subsequently denied North’s petition for a writ of mandamus to prevent the transmission. In re Oliver L. North, No. 88-5438 (D.C.Cir. Jan. 4, 1989) (order).
Together with or shortly after submitting his narrative statement, North noticed 300 classified documents; at subsequent in camera section 6 hearings, however, he provided only “generalized” explanations as to the documents’ relevance and materiality. United States v. North, 713 F.Supp. 1436, 1438 (D.D.C.1989). At this point, to overcome “legal gridlock,” id., the District Judge laid out general categories of classified information that the defense could introduce at trial, and made specific rulings concerning particular documents that North had noticed. See id. at 1438-41. Finally, the District Court denied North’s motion for notice by the IC pursuant to section 6(b)(1), United States v. North, Cr.No. 88-0080-02, 1989 WL 12036 (D.D.C. Jan. 19, 1989), and did not respond to North’s motion under section 6(f) for disclosure of the information that the prosecution expected to use in rebutting his classified information, see Brief for Appellant at 53 n. 91.
C. Merits of North’s Challenges Under CIPA
North suggests that by requiring the transmission of his narrative statement to the IC, by denying his motions for notice under sections 6(b)(1) and (2), and by ignoring his motion for notice under section 6(f), the District Court violated the fundamental principle of reciprocity in pretrial disclosures, laid down by the Supreme Court in Williams v. Florida, 399 U.S. 78, 90 S.Ct. 1893, 26 L.Ed.2d 446 (1970), and Wardius v. Oregon, 412 U.S. 470, 93 S.Ct. 2208, 37 L.Ed.2d 82 (1973). We do not believe, however, that the District Judge’s lack of strict adherence to CIPA’s sequential directives is a ground for reversing the convictions in this case.
We agree with North that the District Judge did not move straightforwardly down the procedural path set out in section 6. Nevertheless, on appeal, North points to no actual injury or prejudice to his trial preparation or presentation that resulted from the District Judge’s application of CIPA. The section 6 hearings on the IC’s classified information, together with documentation provided to North through discovery, see supra note 36, appear to have provided North, in large part, with the information he would have received had his section 6(b)(1) motion been granted. Although North contends that he learned “nothing about the substance of the IC’s case” because that motion was denied, he acknowledges that the IC informed him of “what information was classified in particular documents.” Reply Brief for Appellant at 21 n. 38. Since section 6(b)(1) required the IC to provide North only “with notice of the classified information that is at issue,” CIPA, 18 U.S.C.App. § 6(b)(1), North in effect concedes that he suffered no cognizable injury from the denial of his section 6(b)(1) motion.
After his November 14 and December 19 section 5 submissions, North did not make a section 6(b)(2) motion for notice of “such details as to ... the indictment ... as are needed to give the defendant fair notice to prepare for the [section 6(a) ] hearing.” Id. § 6(b)(2). The lack of a timely section 6(b)(2) filing, coupled with the substantial information transmitted to North through discovery, see supra note 36, suggest that North had sufficient information about the indictment without further notice.
Nonetheless, we believe that the District Court erred in its handling of *902North’s section 6(f) motion. Without explanation, the District Court neither required the government to specify “the information it expect[ed] to use to rebut [North’s] classified information,” id. § 6(f), nor found explicitly that the “interests of fairness” did not warrant accession to North’s request.40 In our view, ignoring a statutorily sanctioned claim for reciprocal disclosure, without a finding that the interests of fairness do not require that disclosure, is error.
North, however, has adduced no evidence of prejudice resulting from the District Court’s error. Despite the benefit of a full trial record, North fails to demonstrate how he was surprised or prejudiced by prior unawareness of any of the evidence presented by the IC at trial to “refute” his defenses. Thus, North does not identify any hitherto IC’s attempt to rebut his contention that high executive branch officials knew of and authorized his conduct. See Reply Brief for Appellant at 21 n. 38. North also does not claim that he was surprised by the government’s evidence refuting his defense under Count 10 that he accepted the home security system in order to protect his family. See id. Absent any such showing of surprise at trial, therefore, we conclude that the trial judge committed only nonreversible harmless error by ignoring North’s section 6(f) motion.41
In several instances, moreover, the District Judge provided North with more procedural safeguards than CIPA requires. For example, at the ex parte hearing in July 1988, North was able to explain to the District Judge, outside the IC’s presence, the significance of classified documents to his case; as a result of that hearing, North received additional relevant classified information from the IC. See United States v. North, 698 F.Supp. at 325. Further, CIPA contains no requirement that the judge permit a defendant to refile his section 5 notice after finding his first filing inadequate. CIPA also does not seem to mandate a section 6(a) hearing on redactions made by the prosecution in classified information to be used in its case-in-chief. Finally, after finding North’s second section 5 filing unacceptable, the District Judge imposed only a circumscribed preclusion on North’s use of classified information. See United States v. North, 708 F.Supp. at 398-99.
North states that the District Court’s transmission of his narrative statement to the IC “confirmed” or “made clear” various aspects of his defense, Reply Brief for Appellant at 21 n. 37, and denied him the advantage of surprise at trial. Although CIPA enables the government to investigate “facts crucial to the determination of guilt or innocence,” Wardius, 412 U.S. at 474, 93 S.Ct. at 2212 (quoting Williams, 399 U.S. at 82, 90 S.Ct. at 1896), and to tailor its arguments accordingly, the defendant’s rights remain intact, provided that the defense has similar, though not necessarily identical, discovery opportunities. North enjoyed broad discovery before implementation of CIPA began, see supra note 36, and the government’s statements during the section 6 hearings on classified material in its case-in-chief gave North insight not required by CIPA into the prosecution’s trial strategy. United States v. *903North, 708 F.Supp. at 401. As the District Court observed, the IC gained little tactical advantage from receiving North’s narrative statement because prosecution witnesses were already “committed under oath and otherwise to their positions.” Id. Since North’s narrative statement shed important, if limited, light on his section 5 documentary notice, id. at 400, the judge’s decision to transmit the statement was appropriate.42
In sum, the District Court’s implementation of CIPA ultimately required each side to reveal substantial aspects of its arguments to its opponents. This result was envisioned by Congress, see Collins, 720 F.2d at 1200, and is consistent with the “salutary” development of “a system of liberal discovery which gives both parties the maximum possible amount of information with which to prepare their cases and thereby reduces the possibility of surprise at trial.” Wardius, 412 U.S. at 473-74, 93 S.Ct. at 2211. In the absence of any showing by North of actual injury, we find no constitutional violation arising out of the application of CIPA in this case. Cf. id. (finding unconstitutional state rule requiring that defendant provide prosecution with notice of alibi but not allowing for reciprocal discovery by defendant); Mauricio v. Duckworth, 840 F.2d 454 (7th Cir.) (due process violated when prosecution deliberately leaves name of its alibi rebuttal witness off witness list provided, after court order, to defense), cert. denied, 488 U.S. 869, 109 S.Ct. 177, 102 L.Ed.2d 146 (1988).
VIII. JueoR Dishonesty
North contends that he was denied his Sixth Amendment right to an impartial jury because a trial juror lied under oath, on both a pretrial jury questionnaire and in a post-trial hearing, about her immediate family’s involvement in judicial proceedings. We are not persuaded by North’s argument.
A. Background
Before trial, jurors were asked several questions, including whether they or any member of their immediate family had “ever been involved as a party to or appeared as a witness in any court proceeding (civil or criminal) or in any investigation by a federal or state authority or by an official legislative body or agency.” JA at 3050 (Tara King hearing exhibit). Tara King, who was eventually selected as a trial juror, checked the box marked “No” even though several of her brothers had been charged with criminal conduct, one was sent to prison, and King herself had testified before the grand jury investigating a robbery allegedly committed by one of her brothers. After trial, upon obtaining evidence that King had improperly completed her pretrial questionnaire, North moved for an in camera hearing concerning King’s qualifications and for a mistrial. See United States v. North, 716 F.Supp. 652, 653-55 (D.D.C.1989).
At the hearing, King testified that she had “forgotten” about one of her brothers’ guilty plea, conviction, and time in jail. See Transcript of Evidentiary Hearing, June 28, 1989, at 13, 16, 26. Although the District Judge did not “credit” King’s testimony of forgetfulness, he denied North’s motion for a mistrial because North had not demonstrated any resultant bias against him “by fact or implication.” United States v. North, 716 F.Supp. at 655, 656.
*904B. Analysis
At issue is whether deliberate concealment of information at voir dire is sufficient to require a mistrial, absent a showing of actual bias. The Supreme Court has laid down the following standard for overturning a conviction when a juror withholds critical information on voir dire:
[A] party must first demonstrate that a juror failed to answer honestly a material question on voir dire, and then further show that a correct response would have provided a valid basis for a challenge for cause. The motives for concealing information may vary, but only those reasons that affect a juror’s impartiality can truly be said to affect the fairness of a trial.
McDonough Power Equipment, Inc. v. Greenwood, 464 U.S. 548, 556, 104 S.Ct. 845, 850, 78 L.Ed.2d 663 (1984). Although McDonough involved a “mistaken, though honest, response” to a voir dire question in a civil case, id. at 555, 104 S.Ct. at 850, the test it lays out has been applied in criminal cases as well. See, e.g., United States v. Aguon, 851 F.2d 1158, 1170 (9th Cir.1988) (en banc); United States v. Casamayor, 837 F.2d 1509, 1515 (11th Cir.1988) (per curiam), cert. denied sub nom. Barker v. United States, 488 U.S. 1017, 109 S.Ct. 813, 102 L.Ed.2d 803 (1989).
Read along with the concurrences of five Justices, McDonough suggests that an aggrieved party must show that the juror’s correct response at voir dire would have demonstrated actual bias. Three Justices explained that while “in most cases, the honesty or dishonesty of a juror’s response is the best initial indicator of whether the juror in fact was impartial,” a trial court retains the option of ordering a post-trial hearing “at which the movant has the opportunity to demonstrate actual bias or, in exceptional circumstances, that the facts are such that bias is to be inferred.” 464 U.S. at 556-57, 104 S.Ct. at 850 (Blackmun, J., joined by Stevens and O’Connor, JJ., concurring). Two other Justices argued even more explicitly that a deliberate lie, without more, is insufficient evidence of juror bias: “Whether the juror answered a particular question on voir dire honestly or dishonestly, or whether an inaccurate answer was inadvertent or intentional, are simply factors to be considered in this latter determination of actual bias.” Id. at 558, 104 S.Ct. at 851 (Brennan, J., joined by Marshall, J., concurring in the judgment).
Judge Gesell found that a truthful answer by King might have led either side to strike her. United States v. North, 716 F.Supp. at 655. Under McDonough, however, a “valid basis for a challenge for cause,” 464 U.S. at 556, 104 S.Ct. at 850, absent a showing of actual bias, is insufficient justification for a mistrial.43 King’s concealment, then, is only one factor — albeit an important one — in the critical test for actual bias. As to this broader question, the District Court found that “[n]o proof was presented indicating that [she] was unfair or that she failed in any way to serve conscientiously.” United States v. North, 716 F.Supp. at 655. While King may have felt that full disclosure “would prevent her being considered for jury service ... she had no desire to help or to hurt North or the prosecutor.” Id. On appeal, North adduces no evidence of actual bias to call into question the District Court’s findings. Although King apparently wanted to serve as a juror at North’s trial, id., North offers no argument why her omissions on the questionnaire indicated that she was biased against him.
North argues on the basis of United States v. Colombo, 869 F.2d 149 (2d Cir.1989), that King’s deliberate concealment on the pretrial questionnaire was per se evidence of her lack of impartiality. In Colombo, the Second Circuit considered the partiality of a juror who wanted to serve on a RICO trial and, therefore, allegedly concealed her brother-in-law’s employment as a government attorney. Id. at 150. Noting that the juror’s alleged concealment effectively discouraged the magistrate and defense counsel from asking follow-up questions or from dismissing her peremptorily, id. at 151, the court concluded that if *905the juror deliberately and willingly lied about her relationship with her brother-in-law, she “exhibited an interest strongly suggesting partiality.” Id. at 152. The court remanded for a finding as to whether the juror’s brother-in-law actually was a government attorney; if he was, the defendant’s conviction would be vacated.
We decline to follow Colombo insofar as it stands for the proposition that juror dishonesty at voir dire is per se evidence of the juror’s partiality and therefore compels a mistrial. In our view, such a rule is inconsistent with the Supreme Court’s instruction that juror dishonesty does not, without more, prove actual bias. Nor are we persuaded, as a policy matter, that the Second Circuit’s more stringent approach increases in a constructive manner the incentives for either side to investigate vigorously the possibility of concealment by jurors at voir dire. Even without a per se rule, the defense is motivated to ask searching questions during voir dire in order to exercise its peremptory challenges effectively. A Colombo-type rule further encouraging defendants to investigate jurors in a criminal case might, indeed, produce a backlash effect by inducing prospective jurors to evade service. Under present practice, moreover, the defense has a substantial incentive to investigate leads on juror voir dire misstatements throughout the trial because of the possible “reward” of a mistrial if bias can also be shown.
By doing away with the need for any showing of actual bias, a per se rule would, of course, lighten the defense’s burden in obtaining a mistrial. A mere showing of dishonesty would suffice. Fear of such an eventuality might at least theoretically induce the prosecution to question prospective jurors more thoroughly at voir dire.
Nevertheless, we believe that a per se rule’s effect on prosecutorial behavior would be marginal at best. Under McDon-ough’s, standard, the prosecution is motivated to examine potential jurors carefully enough to avoid seating a biased juror. Furthermore, as an officer of the court, the prosecution must turn over any information that it uncovers concerning juror lies or concealments. Even with a Colombo-type rule in place, the prosecution is unlikely to have the time or resources to investigate every juror statement at voir dire for bias or perjury. In fact, since a discovery of untruthfulness would necessitate a mistrial, the per se rule might actually discourage prosecutorial investigations. On balance, then, since a per se rule would likely have only a minimal effect on either prosecution or defense conduct, we decline to follow the Second Circuit’s course rather than the approach drawn from the Supreme Court’s opinions in McDonough.44
In sum, the District Court applied the correct legal standard in addressing North’s claim of juror misconduct. Seeing no evidence that the District Judge’s factual findings concerning King’s lack of bias were clearly erroneous, United States v. Manner, 887 F.2d 317, 327 (D.C.Cir.1989), cert. denied, — U.S.-, 110 S.Ct. 879, 107 L.Ed.2d 962 (1990), we affirm his denial of North’s motion for a mistrial.
IX. Videotape
After the prosecution had rested its case and on the eve of the presentation of defense evidence, North, by motion, sought leave of the District Court to introduce a three-to-four-hour excerpted version of John Poindexter’s thirty hours of immunized testimony before the congressional committees investigating the Iran/Contra affair. The District Court denied the motion in United States v. North, 713 F.Supp. 1450 (D.D.C.1989) (hereafter “Videotape Memo ”). North now contends that the District Court erred in not admitting the videotape under the prior testimony exception to the hearsay rule, Fed.R.Evid. *906804(b)(1),45 or under the “catch-all” exception to the hearsay rule, Fed.R.Evid. 804(b)(5).46 We disagree. The District Court acted well within its broad discretion over evidentiary matters in its denial of the motion to introduce the Poindexter videotape.
As the District Court noted, “[t]here can be no dispute that the videotape is hearsay.” Videotape Memo, 713 F.Supp. at 1451.47 Therefore, the testimony is not admissible unless it comes within some exception provided by the Rules of Evidence or other controlling authority. Fed.R.Evid. 802. North asserts that the videotape comes within the prior testimony exception created by Rule 804(b)(1). However, as the language of the rule, see note 45, supra, makes plain and as the District Court correctly held, this exception only applies where “the party against whom the testimony is ... offered ... had an opportunity and similar motive to develop the testimony by direct, cross, or redirect examination.” Fed.R.Evid. 804(b)(1).48 North flatly asserts that “[t]he IC and Congress ... constitute the same ‘party’ for purposes of Rule 804(b)(1)” because “[e]ach is part of the United States Government_” Brief for Appellant at 49. However, we agree with the District Court that “[t]he Independent Counsel is not the Congress.... ” Videotape Memo, 713 F.Supp. at 1451. The Supreme Court recognized the distinction between the entities in Morrison v. Olson, 487 U.S. 654, 108 S.Ct. 2597, 101 L.Ed.2d 569 (1988). In that case, the High Court recognized the IC as functionally within the executive branch and observed that Congress has “no powers of control or supervision over an independent counsel.” 487 U.S. at 694, 108 S.Ct. at 2620. Obviously, the IC has no powers of control over the Congress. The IC took no part in the examination of Poin-dexter, or any other examination in the congressional hearings. Indeed, as we noted in our discussion of the Kastigar issues, supra at Part I, Congress acted over the vigorous objection of the Independent Counsel in granting immunity to its witnesses, and the IC not only did not conduct the examination but was at pains to avoid exposure to any part thereof.
Further, as the District Court noted, there are no prior decisions of this or any other court holding that a congressional committee is the same party as an executive branch prosecutor for purposes of the prior testimony exception. See Videotape Memo, 713 F.Supp. at 1451. Such limited parallel authority as does exist does not support North’s claim that the District Court committed reversible error in not finding the IC and the Congress to be the same party. In a civil action applying a California Rule of Evidence paralleling Rule 804(b)(1), for example, the Ninth Circuit held that the Federal Deposit Insurance Corporation was not the same party as the United States, the prosecutor in the *907criminal action in which the prior testimony had been taken. FDIC v. Glickman, 450 F.2d 416, 418 (9th Cir.1971). See also State v. Freeman, 440 P.2d 744, 759 (Okla.1968) (excluding from a state criminal trial evidence taken at a legislative hearing).
North argues, however, that the requirements of the Rule 804(b)(1) exception should not be construed narrowly to exclude key evidence offered by a defendant as the requirements are, in North’s view, “primarily designed to protect the Sixth Amendment confrontation rights of criminal defendants....” Brief for Appellant at 49. This assertion is open to much question as the hearsay rule and its exceptions, like the rest of the Federal Rules of Evidence, govern both civil and criminal “proceedings in the courts of the United States and before United States bankruptcy judges and United States magistrates.... ” Fed.R.Evid. 101. Whatever the strength of North’s basic assumption, the District Court’s decision here comports with other applications of the same-party requirement in criminal cases. In United States v. McDonald, 837 F.2d 1287, 1291-93 (5th Cir.1988), the Fifth Circuit held that the district court had not erred in refusing to admit under the prior testimony exception depositions taken in a civil action between the criminal defendant and the alleged victim of the fraud which the United States was prosecuting. Likewise, in United States v. Kapnison, 743 F.2d 1450, 1458-59 (10th Cir.1984), cert. denied, 471 U.S. 1015, 105 S.Ct. 2017, 85 L.Ed.2d 299 (1985), the Tenth Circuit found the exception unavailable to a defendant attempting to offer depositions taken in a civil case arising from the same facts as the criminal prosecution. We find no more reason to relax or dispense with a requirement fixed by the plain words of the rule than did our sister circuits.
In short, we find no error in the District Court’s determination that North’s proffered videotape does not meet the same-party requirement, particularly as we apply the abuse-of-discretion standard of review. United States v. Williams, 738 F.2d 172, 178 (7th Cir.1984); United States v. MacDonald, 688 F.2d 224, 233 (4th Cir.1982), cert. denied, 459 U.S. 1103, 103 S.Ct. 726, 74 L.Ed.2d 951 (1983); United States v. Poland, 659 F.2d 884 (9th Cir.), cert. denied, 454 U.S. 1059, 102 S.Ct. 611, 70 L.Ed.2d 598 (1981).
We further agree with the District Court that even if Congress and the IC were the same party, the proffered videotape does not meet the further requirement of Rule 804(b)(1) that the occasion of the prior testimony must have presented the opposing party with “an opportunity and similar motive to develop the testimony by direct, cross, or redirect examination.” The IC in North’s case is a prosecutor seeking to lay before a jury those facts which he contends will support a criminal conviction. Although Congress in authorizing and conducting the Iran/Contra hearings may have had an intent to determine whether illegal conduct had occurred, and to identify government officials who might have engaged in illegal activity, the political and legislative goals of Congress are far different from the prosecutorial commission of the IC. Even where congressional questioners sound like prosecutors, the goals, methods, restraints and results of the former are different from those of the latter, and they are subject to different influences and motives, as the District Court observed. Not only did the IC not have an opportunity to cross-examine witnesses before the committees, but, because of his concern for the strength of his criminal case he did not even want some of them, including Poindexter, to be immunized or examined. Witnesses before the committees often gave long, rambling statements more like speeches than answers to interrogatories. Witnesses were allowed to consult with counsel before responding — a practice recently criticized by the Supreme Court even in a situation where cross-examination actually took place:
Permitting a witness, including a criminal defendant, to consult with counsel after direct examination but before cross-examination, grants the witness an opportunity to regroup and regain a poise and sense of strategy that the un*908aided witness would not possess.... [Cjross-examination of a witness who is uncounseled between direct examination and cross-examination is more likely to lead to the discovery of truth....
Perry v. Leeke, 488 U.S. 272, 109 S.Ct. 594, 601, 102 L.Ed.2d 624 (1989).
As the District Court observed, “[cjon-gressional examination was shaped in part by the demands of television and electoral politics, rather than by the rules of evidence and the norms of a fair adversary proceeding. Indeed, there was no fact finder in the process.” Videotape Memo, 713 F.Supp. at 1451. We concur, and readily affirm that the District Court’s conclusion evidenced no abuse of discretion.
North further contends that the District Court’s exclusion of the videotape violated his constitutional rights, citing Chambers v. Mississippi, 410 U.S. 284, 302, 93 S.Ct. 1038, 1049, 35 L.Ed.2d 297 (1973), for the proposition that “where constitutional rights directly affecting the ascertainment of guilt are implicated, the hearsay rule may not be applied mechanistically to defeat the ends of justice.” Certainly, this states a constitutional rule as announced by the Supreme Court. But, as the District Court found, Chambers is inap-posite. As an initial matter, Chambers limited itself to its own facts and circumstances. See Chambers, 410 U.S. at 302-303, 93 S.Ct. at 1049-50. Chambers involved an extremely strict application of state evidentiary rules and the consequent exclusion of key pieces of defense evidence in the capital trial of a black man for the alleged murder of a white police officer. The facts in North’s case are not nearly so extreme, and even North does not argue that the Poindexter videotape is the key piece of evidence upon which his case stands or falls. Also, unlike the testimony that the defendant desired to present in Chambers, the videotape here was the subject of an llth-hour request by North to admit a tape that his lawyers had edited in a fashion, presumably, not unfavorable to North’s case. Nor does the record here present the hallmarks of procedural arcana, racial prejudice and fundamental unfairness that characterized the record in Chambers. See id. at 285-94, 93 S.Ct. at 1041-45. For these reasons, we see no need to review the videotape ourselves, despite the District Court’s “hasty” review. The District Court was undoubtedly correct when it concluded that North “simply relies on a broad general claim of relevance, which in this context is not enough, since relevance in a case of this nature has no particular focus.” Videotape Memo, 713 F.Supp. at 1451-52. In light of our conclusions concerning North’s authorization defense, see supra Part III(A), Poindexter’s testimony in any form can hardly be considered as the key piece of exculpatory evidence, unlike the crucial testimony at issue in Chambers. Again, we find no error in the exclusion of the videotape.
North’s final claim that the District Court erred in failing to admit the videotape under the catch-all exception, Fed.R. Evid. 804(b)(5), is entirely without merit. That exception allows the admission only of hearsay statements “having equivalent circumstantial guarantees of trustworthiness” to the express exceptions in the foregoing rule. Fed.R.Evid. 804(b)(5). It permits the exceptional admission of such hearsay only where the trial court has determined that “the general purposes of these rules and the interests of justice will best be served by admission of the statement into evidence.” Id. Even then, such “a statement may not be admitted under this exception unless the proponent of it makes known to the adverse party sufficiently in advance of the trial or hearing to provide the adverse party with a fair opportunity to prepare to meet it, the proponent’s intention to offer the statement and the particulars of it....” Id.
The necessity for the exercise of a broad discretion by the trial judge is evident from the language of the rule and is underlined by the facts of this case. The indicia of trustworthiness of a potentially self-serving declaration in the context of the televised congressional hearings; the consistency of the admission of the testimony with the purposes of the rules; the service of the interests of justice by the *909admission of the proposed evidence; and the adequacy of the notice are ail matters which do not readily lend themselves to review as matters of law. We agree with the Eleventh Circuit that an appellate court should be “particularly hesitant to overturn a trial court’s admissibility ruling under the residual hearsay exception absent a ‘definite and firm conviction that the court made a clear error of judgment in the conclusion it reached based upon a weighing of the relevant factors.’ ” Balogh’s of Coral Gables, Inc. v. Getz, 798 F.2d 1356, 1358 (11th Cir.1986) (en banc) (quoting Page v. Barko Hydraulics, 673 F.2d 134, 140 (5th Cir.1982)). Accord Huff v. White Motor Corp., 609 F.2d 286, 291 (7th Cir.1979). Here, we are far from such a “definite and firm conviction,” and find no error in the District Court’s denial of North’s motion to admit the Poindexter videotape.
X. Jury Selection
The Jury Selection and Service Act (“JSSA”), 28 U.S.C. §§ 1861 et seq. (1988), sets out two fundamental principles governing jury selection in federal courts. First, it establishes that litigants in federal court entitled to a trial by jury "shall have the right to grand and petit juries selected at random from a fair cross section of the community in the district or division wherein the court convenes.” Id. § 1861. In addition, the JSSA provides that disqualifications, exemptions, and excusáis from jury service may be granted only for certain objective reasons, such as a showing of undue hardship or extreme inconvenience, inability to render impartial jury service, peremptory challenge, or good cause. See id. § 1866(c). See also United States v. Savides, 787 F.2d 751, 754 (1st Cir.1986). North argues that the District Court injected an “improper nonrandom criterion” into the selection process by excusing, without further inquiry, all prospective jurors who noted their exposure to North’s immunized testimony on the pretrial questionnaire while individually questioning prospective jurors who denied exposure on the questionnaire. Some of these latter jurors were excused for cause; others were selected for the jury. Brief for Appellant at 56; Affidavit of Barry S. Simon, Feb. 7, 1989, JA at 2416-17.49
North overstates the JSSA’s mandate for randomness. As the House of Representatives Judiciary Committee Report on the JSSA bill explained,
If the voter lists are used and supplemented where necessary, and if the procedures outlined in the bill are otherwise rigorously followed it is no departure from the standards of the legislation that the qualified jury wheel, the venire or array, or the jury itself, may not reflect a community cross section. The act ... does not require that at any stage beyond the initial source list the selection process shall produce groups that accurately mirror community makeup.
H.R.Rep. No. 1076, 90th Cong., 2d Sess. 5 (1968), 1968 U.S.Code Cong. & Admin. News 1792, 1794. Since North challenges neither the jury list from which the venire was selected nor the venire itself, the JSSA’s randomness mandate is not germane to his claim. Compare, e.g., United States v. Kennedy, 548 F.2d 608, 610 (5th Cir.) (prohibiting use of volunteers to fill out jury list pursuant to JSSA), cert. denied, 434 U.S. 865, 98 S.Ct. 199, 54 L.Ed.2d 140 (1977); United States v. Branscome, 529 F.Supp. 556 (E.D.Va.) (dismissing indictment handed down by grand jury panel composed, in part, of volunteers), aff'd, 682 F.2d 484 (4th Cir.1982).
More properly, North’s claim requires us to consider whether the District Judge’s differential treatment of jurors based on their written answers on the pretrial questionnaire constituted an abuse of his discretion to excuse jurors for inability *910to render impartial jury service. We do not find the District Judge’s approach problematic. In light of the legitimate concern about juror exposure to North’s immunized testimony, the District Court stated that “anybody who affirmatively says that they have heard the testimony of Col. North at the congressional hearing should not be called.” Voir Dire Transcript at 342. Underlying the District Court’s conclusion is the reasonable presumption that jurors who noted their exposure on the questionnaire had such significant recollections of North’s immunized testimony that they would be unlikely to render an impartial verdict. Those jurors were, therefore, properly dismissed “for cause.” See United States v. North, Cr. No. 88-0080-02, 1989 WL 13416 (D.D.C. Feb. 9, 1989) (order).50 The District Judge’s individual interrogation of jurors who denied exposure on the written form further guarded against seating jurors who had been substantially exposed to North’s immunized testimony. Although some jurors in this latter “exposed” group were seated while others were excused, we defer to the District Judge’s determination that the minimal exposure of the selected jurors did not render them partial to either party. See United States v. Anderson, 509 F.2d 312, 322 (D.C.Cir.1974) (noting trial judge’s discretion in jury selection), cert. denied, 420 U.S. 991, 95 S.Ct. 1427, 43 L.Ed.2d 672 (1975); City of Cleveland v. Cleveland Electric Illuminating Co., 538 F.Supp. 1240, 1256-57 (N.D.Ohio 1980) (judge to determine at voir dire whether individual jurors made out sufficient claim of undue hardship under § 1866(c)).
Accordingly, we find that the District Court’s “for cause” dismissals were justified and that no “substantial failure to comply” with the JSSA resulted. 28 U.S.C. § 1867(a). We do not reverse North’s convictions on this ground.
XI. Verdiot Form
The jury’s verdict form on Counts 6 and 9 read as follows:

Count Six

Obstruction of Congress in November 1986. 18 U.S.C. § 1505:
Guilty_ Not Guilty_
If, but only if, you have found the defendant Not Guilty, answer the following:
Aiding and Abetting. 18 U.S.C. § 2: Guilty_ Not Guilty_

Count Nine

Concealing, Removing, Mutilating, Obliterating, Falsifying and Destroying Official Documents. 18 U.S.C. § 2071(b).
Guilty_ Not Guilty_
If, but only if, you have found the defendant Not Guilty, answer the following:
Aiding and Abetting. 18 U.S.C. § 2:
Guilty_ Not Guilty_
JA at 691-92. North maintains that we must reverse his conviction on these Counts because the verdict form required the jury, in effect, to return “special verdicts” and, as a result, deprived North of his “right” to a general verdict. Brief for Appellant at 60-61. We agree that as a general matter in criminal cases, the preferable practice is to require the jury to come to one general verdict as to each count. See Fed.R.Crim.P. 8(a) (implying that two or more offenses charged in same indictment must be charged in separate count for each offense); Gray v. United States, 174 F.2d 919, 923 (8th Cir.) (reversing conviction because verdict form allows jury to find defendant guilty several times in single count), cert. denied, 338 U.S. 848, 70 S.Ct. 90, 94 L.Ed. 519 (1949). Judicial distaste for “special verdicts” in criminal cases results from a concern “that the jury [will be] led to its conclusion ‘[b]y a progression of questions each of which seems to require an answer unfavorable to the defendant.’ ” United States v. Desmond, *911670 F.2d 414, 419 (3d Cir.1982) (verdict form requiring jury to determine each element of three counts not plain error) (quoting United States v. Spock, 416 F.2d 165, 182 (1st Cir.1969) (jury required to answer ten separate questions on one conspiracy count)). On the other hand, courts may employ special verdict forms when the finding of an overt act is constitutionally necessary to conviction, see Kawakita v. United States, 343 U.S. 717, 72 S.Ct. 950, 96 L.Ed. 1249 (1952), or when the defendant requests or approves a special verdict as a means of more precisely determining an appropriate and fair punishment, see United States v. Dennis, 786 F.2d 1029, 1041 (11th Cir.1986), cert. denied, 481 U.S. 1037, 107 S.Ct. 1973, 95 L.Ed.2d 814 (1987); see also United States v. Ogull, 149 F.Supp. 272, 275-78 (S.D.N.Y.1957).
Our case falls between these extremes. Since 18 U.S.C. § 2 makes an aider and abettor “punishable as a principal,” the special verdict form did not aid North by mitigating his punishment under Count 6. At the same time, the verdict form did not guide the jury towards a guilty verdict by requiring them to find either the elements of the crime charged or a series of facts from which criminal activity would naturally be inferred. Nor did the form allow the jury to find North guilty twice on a single count.
The form provided the jury two alternative theories for finding North guilty of a single count. The First Circuit has called such practice “error,” United States v. Southard, 700 F.2d 1, 16 (1st Cir.), cert. denied sub nom. Ferris v. United States, 464 U.S. 823, 104 S.Ct. 89, 78 L.Ed.2d 97 (1983), presumably because it gives the jury two chances to reach a guilty verdict in one count. That determination, however, was not controlling in the outcome of the case, so it was “dictum.” Defense counsel in Southard had approved the form at trial and the court of appeals, applying a “plain error” standard on review, refused to overturn the conviction. Id.
As Judge Gesell instructed the jury, the evidence on Counts 6 and 9 was susceptible to a finding of guilt either on the principal statutes in issue — 18 U.S.C. § 1505 or § 2071(b) — or on the aiding and abetting statute, 18 U.S.C. § 2. JA at 678. The verdict form would have been unobjectionable had it asked the jury one question in both Counts 6 and 9: whether North was guilty of either the principal offense or of aiding and abetting. The form that was employed merely broke this disjunctive question into its component parts. We see no reason, therefore, to reverse his convictions on Counts 6 and 9 because of the verdict form. We do suggest, however, that in the future, absent good cause for employing the kind of form used at North’s trial, district judges ask for general verdicts that cover both the “primary” offense, such as a violation of 18 U.S.C. § 1505 or § 2071(b), and aiding and abetting, 18 U.S.C. § 2. Such general verdicts will be less likely, in the ordinary run of cases, to generate disputes.
XII. Venue
North contends that the District Court committed error in denying his motion for directed verdict or judgment n.o.v. on Count 10 of the indictment because the venue for this offense did not lie in the District of Columbia. 18 U.S.C. § 201(c)(1)(B) applies to “[wjhoever ... receives, accepts, or agrees to receive ... anything of value personally for or because of any official act....” Count 10 charged that North violated this statute by “accepting], receiving] and agreeing] to receive” a security system for his Virginia home from Richard Secord. As North’s brief reminds us, venue for an offense lies in the district in which the defendant committed unlawful acts.51 Venue for Count 10 was therefore proper in a district in which North received or accepted the security system, or agreed to receive it. See, *912e.g., United States v. White, 887 F.2d 267, 272 (D.C.Cir.1989).
Invoking both the Sixth Amendment and the language of section 201(c)(1)(B), North contends that the evidence supports venue only in the Eastern District of Virginia, the location of his residence. If' he “accepted]” or “agree[d] to receive” the home-security system anywhere, he argues, then it must have been in Virginia. We cannot agree.
Although North’s statements of the law are incontrovertible, his argument ignores a substantial portion of the evidence in the case. As the trial court found, the record contains ample evidence from which “[a] reasonable jury could find by a preponderance of the evidence that while in Washington, D.C. North accepted or agreed to receive the security system for his home.” United States v. North, 716 F.Supp. 644, 647 (D.D.C.1989). Specifically, the witness Robinette testified that he and Secord met with North in North’s office in the Old Executive Office Building in Washington, D.C. after Robinette had visited North’s home in Virginia. Some initial discussion of the security fence had taken place in Virginia before Robinette’s visit to the residence and the Robinette/Secord/North meeting. Robinette testified that during the meeting in the District of Columbia he offered North certain information concerning the system. North gave Robinette approval to continue with work on the system by saying “ ‘It sounds like you’re on the right track.’ ” United States v. North, 716 F.Supp. at 648 (quoting the testimony of Robinette).
While venue in the Eastern District of Virginia may no doubt have been proper, venue in Washington, D.C. was proper as well. Venue may lie in more than one district. See, e.g., United States v. DeLoach, 654 F.2d 763, 765-67 (D.C.Cir.1980), cert. denied, 450 U.S. 933, 101 S.Ct. 1395, 67 L.Ed.2d 366 (1981). In fact, we long ago applied this principle to a claim paralleling the one advanced by North. In Goodloe v. United States, 188 F.2d 621 (D.C.Cir.1950), cert. denied, 342 U.S. 819, 72 S.Ct. 35, 96 L.Ed. 619 (1951), we held that venue here was proper in a bribery case if “the attempt to bribe was commenced, continued or completed here, even though most of the acts relied upon to constitute the crime were committed in Baltimore.” Id. at 622. The Washington meeting suffices to bring the present ease within the rule of Goodloe.
United States v. White, 887 F.2d 267 (D.C.Cir.1989), relied upon by North, is not to the contrary. Although we held in White that venue would not lie in Washington, D.C. when an agreement to pay and accept a bribe had occurred elsewhere and only the effects of the bribe were felt in the District, that is no parallel to the present case. Here acts of offering and accepting a gratuity occurred both in Washington, D.C., and elsewhere, according to the evidence before the jury. In short, we conclude that North’s assignment of error is without merit.52
*913XIII. Aiding and Abetting: Section 2
North raises an allegation of error applicable only to Count 6. On Count 6, the jury acquitted North as a principal but convicted him as an aider and abettor. He contends that the District Court erred in denying his motion for a bill of particulars. Specifically, he asserts that he was entitled to such a bill (1) stating whether he was charged with violating 18 U.S.C. § 2(a) by aiding, abetting, counseling, commanding, inducing, or procuring the violation of section 1505, or was instead charged with violating 18 U.S.C. § 2(b) by willfully causing another to violate section 1505; (2) specifying the manner in which he allegedly aided, abetted, etc.; and (3) identifying the alleged principals. North’s contention that it was error to deny his motion has no merit on any of the three asserted bases.
As to the first claim, North cites no authority in support of his proposition, and we have found none. It is well established that the government need not elect between charging a defendant as a principal and as an aider or abettor. United States v. Pollack, 534 F.2d 964, 970-71 (D.C.Cir.), cert. denied, 429 U.S. 924, 97 S.Ct. 324, 50 L.Ed.2d 292 (1976). As we have previously not required the government to opt between guilt as a principal and guilt under section 2 as an aider and abettor, it follows that we will not require an election between the two subsections of section 2.
As to the second specification, North relies principally on a Tenth Circuit case, Cefalu v. United States, 234 F.2d 522 (10th Cir.1956), which stands for the unremarkable proposition that where an indictment “fails to inform the accused with sufficient particularity of the charges against which he will have to defend at the trial, the remedy is to move for a bill of particulars.” Id. at 524 (citations omitted). In the present case, Count 6 provides a rather detailed recitation of the charge the government proposed to prove at trial. It is the law, as recognized in the Cefalu case relied upon by North, that “a motion ... for a bill of particulars enlarging upon the indictment is addressed to the sound judicial discretion of the trial court, and the denial thereof will not be disturbed on appeal unless there was an abuse of discretion.” Id. (citations omitted). Here, we find no abuse of discretion and do not disturb the trial court’s ruling.
As to North’s third argument, in the context of reviewing the sufficiency of evidence we have long rejected the proposition that the principal must be specifically identified in order for the conviction of the aider and abettor to stand. In United States v. Staten, 581 F.2d 878, 887 (D.C. Cir.1978) (citations omitted), we held that “[i]t was not essential that the principal in the operation be identified so long as someone had that status.” We see no reason why the same rule should not apply at the pleading stage.
In sum, we find no reversible error in the District Court’s denial of a bill of particulars as to Count 6, especially given the abuse-of-discretion standard which applies in this context.

. The federal use immunity statute, 18 U.S.C. § 6002, provides as follows:
Whenever a witness refuses, on the basis of his privilege against self-incrimination, to testify or provide other information in a proceeding before or ancillary to—
(1) a court or grand jury of the United States,
(2) an agency of the United States, or
(3)either House of Congress, a joint committee of the two Houses, or a committee or a subcommittee of either House,
and the person presiding over the proceeding communicates to the witness an order issued under this part, the witness may not refuse to comply with the order on the basis of his privilege against self-incrimination; but no *854testimony or other information compelled under the order (or any information directly or indirectly derived from such testimony or information) may be used against the witness in any criminal case, except a prosecution for perjury, giving a false statement, or otherwise failing to comply with the order.

. As we will discuss in Section C(l), infra, the extent of prohibition of "nonevidentiary" use is the subject of much disagreement.

. The memorandum of the District Court’s preliminary consideration of North’s Kastigar claims is styled United States v. Poindexter because North’s case was not yet severed from that of Admiral John Poindexter.

. For similar reasons we are not convinced by the dissent's belief that the Kastigar inquiry should be limited to witnesses who testified about the events underlying the counts on which North was eventually convicted. We do not doubt that North’s credibility could have been compromised by a witness who used the immunized testimony but who happened to testify concerning matters not directly related to the conviction counts. Similarly, such testimony could have influenced North’s decision to waive his right not to testify. The harmfulness of such use is, of course, a question for the District Court to determine on remand.

. After each grand jury witness was sworn, each was instructed as follows:
Certain witnesses have testified under Congressional grants of limited immunity before House and Senate Committees investigating the Iran/Contra matter.... Please make sure that your answers to our questions are based solely on your own personal knowledge and recollection of the events in question. Do not relate to us anything which you learned for the first time as a result of listening to or reading or hearing about immunized testimony.
Kastigar Memo, 698 F.Supp. at 311-12.

. North also contends that the District Judge erred by instructing the jury that having custody over documents "simply means that a record or document came into the person's possession or control as a government official. Someone with custody does not have to be employed as a librarian or as an official record keeper." JA at 647. We find this instruction entirely appropriate: North's implication that he should escape censure for the destruction, alteration, and removal of documents because he was not the official custodian of NSC records would give license to any government official not serving as a "librarian" or "custodian" to violate section 2071(b) with impunity.

. As we note in Part IV of this opinion, the parties are agreed that violations of 18 U.S.C. § 2071(b) such as those charged in Count 9 require the unusually high mental element of knowledge of unlawfulness.

. Of course, that error could also be described as a mistake of fact in that the search would not have been illegal if the facts were as the officer believed them to be — if the officer possessed a valid warrant.

. The same approach would be warranted in the case of a government official enlisting the aid of a private citizen, for instance a police officer seeking assistance in making an unlawful arrest, in part because "the gap ... between a private citizen and a government official with regard to their ability and authority to judge the lawfulness of a particular governmental activity is great." Id. at 948-49 (opinion of Wilkey, J.).

. We do not mean to suggest that criminal defendants in this Circuit could not avail themselves of the defense of reliance on an official misstatement of law as that defense is described in Judge Merhige’s opinion. But that defense is far more circumscribed than the one sought by North here.

. Even though he was actually convicted only of aiding and abetting others in their violation of section 1505, aiders and abettors must possess the same criminal intent as the principals. Section 1505 thus provides the appropriate threshold for North’s criminal intent on Count 6. See United States v. Sampol, 636 F.2d 621, 676 (D.C.Cir.1980).

. As the Ehrlichman court reminded us, any other view would permit a "Becket” defense excusing the commission of murder to free the king from a "turbulent priest.” See Ehrlichman, 546 F.2d at 926 & n. 68.

. The dissent treats this count as if North were convicted of a crime requiring only a generic "specific intent" rather than the unusual intent requirement that the prosecution prove knowl*885edge of unlawfulness. For that reason, the Chief Judge’s opening discussion as to the general implication of our opinion for the administration of criminal law seems to us to be wholly irrelevant.

. North objected to those instructions. Tr. at 8515-18, 8523-24. To be sure, the District Court had earlier instructed the jury that "you may infer the defendant’s intent from the surrounding circumstances. You may consider any statement made and act done or omitted by the defendant at the time, and all other facts and circumstances in evidence which indicate his state of mind, including all testimony of any witness you find credible.” JA at 673. But in the face of the more particular instruction quoted in the text, it is obvious that the jury was not, in fact, free to consider all evidence of authorization in its deliberations.

. As we have already noted, it appears that the instructions were crafted in an attempt to adhere to Circuit precedent on the question of authorization. As we explained earlier, the District Judge faced a difficult task because the Circuit’s precedent was incoherent. But that the- ultimate fault lies with our Court rather than with the District Court renders the instructions no less erroneous.

. Although the IC does argue on appeal that an unreasonable belief that his conduct was legal would not negate guilt, he cites no authority for that proposition. That lack of authority is not surprising because the IC's proposition does not follow logically from the requirement that the prosecution had to prove that North knew he was acting unlawfully.

. The special requirement of the statute at issue here — knowledge of unlawfulness — is of great significance to our decision. We do not suggest that evidence of authorization in this case pertains to the garden-variety specific intent requirement.

. The same is true with respect to the dissent’s concern about unreasonable reliance on an "incompetent or venal” superior. See Wald Dissent at 931.

. We see no basis for the dissent’s claim that this instruction merely prevented the jury from ”exculpat[ing] North on the grounds of authorizations that were not, in its view, even intended to control his conduct, but were mere suggestions or vague permissions to commit illegal acts if he felt like performing them_” Wald Dissent at 930. But it is not implausible that the authorizations at issue here were intended to control North’s conduct, although not specifying particular acts to be performed at a particular time and place. There is also no merit to the dissent’s suggestion that these authorizations would have met the District Judge's specificity limitation if the jury “interpreted them — as North did — as orders to do [particular acts].” Wald Dissent at 930. The jury was not instructed that they were to "interpret” the orders given to North, much less that they could consider how North interpreted them. Indeed, that is precisely the testimony that the jury was forbidden to consider by the specificity instruction. Thus, once the jury determined that the direction itself was not specific as to the expected behavior and time, it was told not to consider it at all, regardless of how specific North interpreted his instructions to be.

. Of course, the evidence of communications from superiors can lead the jury to acquit based on their view that defendant did not have the requisite knowledge of unlawfulness without that evidence justifying an instruction from the judge on the Barker defense of authorization. For that reason, unlike the dissent, see Wald Dissent at 926 we see no anomaly in this.

. Defendants convicted under 18 U.S.C. § 2 of aiding and abetting must have the same intent as defendants convicted under a principal statute. See supra at 881 n. 11.

. It is unclear from the record whether the chronology was also supposed to accompany Poindexter’s testimony. Regardless of whether Casey or Poindexter ever actually presented the false chronology to Congress or destroyed or altered documents, 18 U.S.C. § 1505 criminalizes any corrupt "endeavor” to obstruct a pending congressional investigation.

.Our reading of the record leads us to disagree with the Dissent’s comment that the interrogatory responses “contain indications, which I am not free to reveal, suggesting that Mr. Reagan might well testify consistently with Mr. North’s proffer." Silberman Dissent at 950 n. 26.

. The Dissent contends that "if Mr. Reagan implicitly or indirectly indicated his desires, that would certainly bear on North's view as to whether or not he was authorized by law to destroy the documents.” Silberman Dissent at 948 (emphasis in original) (footnote omitted). That concerns about the President’s "desires”— which, according to North’s own claim, were limited to "efforts to withhold many aspects of the [Iran] initiative from Congress” and to authorizations of "denials" of knowledge of support for the Contras, JA at 3235, 3237 (sealed appendix) — should have led the District Judge to require Mr. Reagan’s testimony strikes us as precisely the "capricious[ ] or needless[ ]” abuse of subpoenas against Presidents and ex-Presidents that the Dissent properly disdains. See Silberman Dissent at 954. Surely the Dissent does not quarrel with the District Judge’s instruction that ”[n]either the President nor any of [North’s] superiors had the legal authority to order anyone to violate the law,” JA at 676, particularly if such “orders," explicit or implicit, represented nothing more than their desires.
Nor do we see the relevance of the Dissent's argument that Mr. Reagan should have been called to testify because "North worked in the White House, only one step removed from the President himself, with what appears to have been enormous responsibility.” Silberman Dissent at 954. There is a big difference between working in the White House and being a step removed from the President; indeed, North himself does not claim that he ever received personal authorizations from the President. See Reply Brief of Appellant.at 16. Even if, as the Dissent claims, North believed he was "doing the President’s bidding, and doing so with regard to a substantive area of national security policy,” Silberman Dissent at 954, neither of those arguments advances any reason why, when confronted with North’s limited claims that the President approved the withholding of information from Congress, the trial judge should have required Mr. Reagan to take the stand so that North could prove that he believed the destruction and alteration of official documents was lawful. Finally, since the criminal statutes themselves prohibited the destruction and falsification of the official documents involved here, independent of any internal NSC regulation, the Dissent’s implication that the application of those statutes somehow unfairly caught North off his guard is unsupportable.

. The District Judge also required that North "demonstrate with requisite specificity in concrete terms" the information that he expected President Reagan to supply. United States v. North, 713 F.Supp. at 1449 (emphasis supplied). In light of the judge's decision not to allow North or his counsel to see Mr. Reagan's answers to the grand jury interrogatories or portions of his diary, this standard may have been too demanding. Nonetheless, any error was harmless because of the negligible likelihood that Mr. Reagan’s testimony would have been exculpatory.

. Unlike the Dissent, therefore, we need not reach the question of whether Mr. Reagan enjoyed a testimonial privilege sufficient to warrant quashing North’s subpoena.

. Thus, the Dissent's contention that Carella is distinguishable from this case because the District Judge’s instruction constituted a "blatant directed verdict,” rather than presumption shifting the burden of proof, does not hold. See Silberman Dissent at 957.

. The Dissent relies heavily on the rulings of three other circuits that declined to apply harmless error analysis when the trial judge found one of the elements of the crime as a matter of law. In none of these cases, however, was the undisputed fact found by the trial judge a logical prerequisite for the jury’s finding of the other elements of the crime; indeed, one of the cases cited by the Dissent suggested that it would have applied harmless error analysis had the "jury finding prerequisite to conviction [been] a logical certainty." United States v. Voss, 787 F.2d 393, 399 n. 4 (8th Cir.), cert. denied, 479 U.S. 888, 107 S.Ct. 286, 93 L.Ed.2d 261 (1986). This distinction is particularly relevant in light of Carella’s emphasis on “whether [a] rational jury could find the predicate acts but fail to find the fact presumed.” 109 S.Ct. at 2421. Additionally, the three circuit cases cited by the Dissent all preceded Carella.

. The Dissent argues that the District Judge’s instruction could not have been harmless because North might have sought to keep information away from interested congressmen without realizing that they constituted a "pending inquiry” within the meaning of 18 U.S.C. § 1505. This claim, however, raises only the question of whether the congressmen’s actions constituted an "inquiry,” not whether their actions were "pending” or "being had,” 18 U.S.C. § 1505, which by hypothesis they were. It is indisputable that the question of whether a proceeding constitutes an inquiry under § 1505 is a matter of law for the court. United States v. Fruchtman, 421 F.2d 1019, 1021 (6th Cir.), cert. denied, 400 U.S. 849, 91 S.Ct. 39, 27 L.Ed.2d 86 (1970).

.North alleges "serious" doubt as to whether congressional inquiries were pending in November 1986 concerning Contra support; since Count 6 charged obstruction of inquiries into both assistance to the Contras and arms sales to Iran, North claims that the trial judge’s error could not be harmless. This contention is mer-itless, however, because the question of whether North’s obstruction related to inquiries into one or both issues is one of "pertinency," not "pend-ency," and is therefore a question of law for the court rather than for the jury. See Sinclair v. United States, 279 U.S. 263, 298, 49 S.Ct. 268, 273, 73 L.Ed. 692 (1928). In any event, the issue is a "Johnny-come-lately,” for North himself made no mention of the subject of the investigation in his proposed jury instructions. JA at 2468-70.

. North does not specify which conviction counts, or whether all three counts, should be reversed on the basis of this argument.

. In his closing argument, North’s counsel stated:
But worst still and beyond anything I have heard in a courtroom, and outrageous to the extent that it should send a course of rage through everybody in this room, is the reference to Adolf Hitler.
This marine, retired, was linked in this courtroom to Adolf Hitler. Some in this room have fought Adolf Hitler. They know what Adolf Hitler was. And this man is not Adolf Hitler and he doesn’t do things like Adolf Hitler, and to suggest it indicates the extraordinary drive, the force, the power of this government to put its might on top of Colonel North, to see what they can say is a crime. You should be offended by it. And you should judge everything they say, because anyone that will link Colonel North to Adolf Hitler is not credible and should not be believed.
Tr. at 8089.

. We do not hold that a general instruction describing the nature of closing argument is *898sufficient in every case of curable prosecutorial misconduct. It may be that in particularly egregious cases, specific curative instructions are required. In the present case, however, the general instruction appears to us to be quite sufficient.

. We last reversed a conviction on the basis of a prosecutor’s reference to "extra-record facts” during closing argument in Garris v. United States, 390 F.2d 862, 866 (D.C.Cir.1968).

. The hearing was originally scheduled for July 14, three days after North’s section 5 filing, see United States v. Poindexter, 698 F.Supp. at 321, but was subsequently rescheduled for July 6, see United States v. Poindexter, Cr. No. 88-00080 (D.D.C. June 24, 1988) (scheduling order).

. Several days earlier, the District Court had issued a broad discovery order, United States v. *900Poindexter, Cr. No. 88-80, 1988 WL 150849 (D.D.C. June 14, 1988) (discovery order), that ultimately gave North access to some 900,000 pages of government documents, a list of government trial witnesses, designation of the documents in the government’s case-in-chief, as well as other records, documents, and effects. See United States v. North, Cr. No. 88-0080-02, 1988 WL 148494 (D.D.C. Nov. 8, 1988) (order).

. North was to receive documentation concerning the funding of Contra support activities, and the IC was also to relate each document in its case-in-chief to the counts in the indictment for which the document would be offered as proof. United States v. North, 698 F.Supp. at 325.

. On November 23, the District Judge ordered North to file by December 19, initially in camera and ex parte, a section 5 notice of all documents and testimonial information relevant and material to the defense that he intended to disclose or cause to he disclosed at trial. United States v. North, Cr. No. 88-0080-02, 1988 WL 129692 (D.D.C. Nov. 23, 1988) (order re CIPA). It is unclear whether the District Judge had already considered North’s November 14 filing when he issued this order.

.The District Judge amended his December 12 order, 708 F.Supp. at 389, on December 22 to require the IC to identify the documents in North’s January 3, 1989 filing that would not be treated as classified and, further, to furnish proposed substitutions and redactions to the documents containing classified information. In addition, North would have one opportunity to notice the same number of additional classified documents as the IC determined to be unclassified in the first notice. United States v. North, *901Cr. No. 88-0080-02, 1988 WL 148479 (D.D.C. Dec. 22, 1988) (order).

. We disagree with the IC’s apparent contention that section 6(f) requires disclosure only of information that the government intends to use in its rebuttal case. Brief for Appellee at 53 n. 101. Clearly, a defendant can be equally prejudiced by "peremptory rebuttal” in the government’s case-in-chief.

. CIPA was specifically designed to minimize the need to "forego[ ] prosecution of conduct [the government] believed to violate criminal laws in order to avoid compromising national security information." S.Rep. No. 823 at 4, reprinted in 1980 U.S.Code Cong. & Admin.News at 4297. Discovery proceedings under CIPA, therefore, entail the kind of strong state interest that may justify an exchange of information between the prosecution and the defense that is not entirely reciprocal. Wardius, 412 U.S. at 475, 93 S.Ct. at 2212. In these circumstances, the Dissent’s repeated invocations of Wardius, id. at 473-76, 93 S.Ct. at 2211-13 — in which the Court considered a state rule precluding reciprocal discovery by the defense without any countervailing state interest — are misplaced. Here, unlike the situation in Wardius, the "State’s inherent information-gathering advantages,” id. at 475 n. 9, 93 S.Ct. at 2212 n. 9, are matched by the defendant's opportunities for engaging in "greymail” to derail legitimate prosecutions.

. The Dissent’s argument that our decision rests on an inapposite test for "surprise” is curious because the Dissent itself cites Wardius ’ express concern about "subjecting [a defendant] to the hazard of surprise concerning refutation of the very pieces of evidence which he disclosed to the State." 412 U.S. at 476, 93 S.Ct. at 2213; see also id. at 473, 93 S.Ct. at 2211 (approving liberal discovery rules that minimize "possibility of surprise at trial”). As we read Wardius, "surprise,” rather than an undifferentiated claim of "harm” unsupported by any evidence of prejudice, is critical to whether a discovery rule is prejudicial to a defendant, particularly when "strong ... state interests” are at stake. Understandably, then, the Dissent provides no support for its assertion that ”[s]tatutes requiring defendants to disclose elements of their cases to prosecutors are inherently suspect and are permissible if and only if defendants receive the corresponding refutation evidence.” Silberman Dissent at 937 (emphasis in original).

. We do not intend to suggest that a blood relationship to a convicted felon necessarily constitutes cause for challenge to a prospective juror in an unrelated case.

. In any event, the grounds for suspecting King of bias are far weaker than the alleged bias in Colombo, a criminal case where the juror in question was related to a government attorney. By contrast, there was no apparent reason why King was likely to favor one side or the other. Consequently, applying Colombo's per se rule here would be particularly inappropriate.

. The prior testimony exception reads as follows:
Testimony given as a witness at another hearing of the same or a different proceeding, or in a deposition taken in compliance with law in the course of the same or another proceeding, [is not excluded by the hearsay rule] if the party against whom the testimony is now offered, or, in a civil action or proceeding, a predecessor in interest, had an opportunity and similar motive to develop the testimony by direct, cross, or redirect examination.

. Fed.R.Evid. 804(b)(5) states in relevant part: A statement not specifically covered by any of the foregoing exceptions but having equivalent circumstantial guarantees of trustworthiness, [may not be excluded by the hearsay rule] if the court determines that ... the general purposes of these rules and the interests of justice will best be served by admission of the statement into evidence. However, a statement may not be admitted under this exception unless the proponent of it makes known to the adverse party [the proponent's intention to offer the statement] sufficiently in advance of the trial or hearing to provide the adverse party with a fair opportunity to prepare to meet it....

. North has never contended to the contrary, either at trial or before this Court. Plainly, the videotaped testimony is within the definition of "hearsay" set forth in Fed.R.Evid. 801(c).

. A further exception where a "predecessor in interest” had such an opportunity and motive is not relied on by North and may be inapplicable to criminal cases in any event. See generally United States v. McDonald, 837 F.2d 1287, 1290-93 (5th Cir.1988).

. The District Judge initially interviewed the jurors who denied exposure on the questionnaire, while keeping the jurors who had noted some exposure on the form "subject to call.” Voir Dire Transcript at 341. Subsequently, he excused for cause all the jurors who had noted their exposure on the questionnaire, along with several unselected jurors who admitted exposure after questioning. United States v. North, Cr. No. 88-0080-02, 1989 WL 13416 (D.D.C. Feb. 9, 1989) (order).

. The judge did not specify to which "cause,” among those listed in section 1866(c), his dismissal referred. In the context of the case, it seems most likely that the "cause” was the juror's inability to render impartial jury service. 28 U.S.C. § 1866(c)(2).

. This principle is of constitutional genesis: "In all criminal prosecutions, the accused shall enjoy the right to a speedy and public trial, by an impartial jury of the State and district wherein the crime shall have been committed....” U.S. Const.Amend. VI. *913obviously satisfied the terms of the statute, and the District Court committed no error.

. North also asserts in a footnote to his venue argument that the District Court erred in instructing the jury to apply a preponderance-of-the-evidence standard, rather than a beyond-a-reasonable-doubt standard, to the question of venue. This assertion is made without citation of authority and is contrary to the unanimous holding of all circuits which have considered the question. United States v. Taylor, 828 F.2d 630, 633 (10th Cir.1987); United States v. Griley, 814 F.2d 967, 973 (4th Cir.1987); United States v. Lewis, 797 F.2d 358, 366 (7th Cir.1986), cert. denied, 479 U.S. 1093, 107 S.Ct. 1308, 94 L.Ed.2d 162 (1987); United States v. Potamitis, 739 F.2d 784, 791 (2d Cir.), cert. denied, 469 U.S. 918, 105 S.Ct. 297, 83 L.Ed.2d 232 and 469 U.S. 934, 105 S.Ct. 332, 83 L.Ed.2d 269 (1984); United States v. Rivamonte, 666 F.2d 515, 517 (11th Cir.1982); United States v. Durades, 607 F.2d 818, 820 n. 1 (9th Cir.1979); United States v. Black Cloud, 590 F.2d 270, 272 n. 2 (8th Cir.1979). We, therefore, reject North’s marginal argument and relegate it to a footnote as did the author of his brief.
North also argues that the District Court’s instructions on Count 10 were erroneous in that they allowed the jury to find North guilty on Count 10 without concluding that North knew that Secord was paying him "compensation for an official act.” Brief for Appellant at 66-67. The District Court instructed the jury that, in order to convict, it would have to find that "the gratuity was received by the defendant for his personal benefit, because of an official act or acts already performed or to be performed in the future_’’ JA at 652. North’s argument on this point is without merit: the instruction