Court Opinion

ID: 9490362
Source: CourtListenerOpinion
Date Created: 2023-08-05 13:41:04.784348+00
Date Added: 2024-06-11T17:54:03.192474
License: Public Domain

JENKINS, District Judge,
concurring in the result.
I join in affirming the district court’s judgment.
I write separately to emphasize the importance of process.
Rule 702 and Daubert
Rule 702 of the Federal Rules of Evidence governs the admissibility of expert testimony in civil and criminal trials:
If scientific, technical or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise.
In Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993), the Supreme Court read Rule 702 to say that “the trial judge must determine at the outset, pursuant to Rule 104(a), whether the expert is proposing to testify to (1) scientific knowledge that (2) will assist the trier of fact to understand or determine a fact in issue.” Id. at 592, 113 S.Ct. at 2796 (footnotes omitted). Daubert requires that the trial judge determine whether proffered scientific expert testimony genuinely qualifies as reliable scientific knowledge. In assessing “knowledge” and its reliability, Daubert demands a searching inquiry as to method. Daubert v. Merrell Dow Pharmaceuticals, Inc., 43 F.3d 1311, 1318 (9th Cir.) (on remand) (“Daubert II”), cert. denied, — U.S. -, 116 S.Ct. 189, 133 L.Ed.2d 126 (1995). Indeed, the Rule 702 inquiry into knowledge should “focus ... solely on principles and methodology, not on the conclusions that they generate.” Daubert, 509 U.S. at 595, 113 S.Ct. at 2797.
A proponent of scientific evidence may satisfy its burden of establishing that the evidence is scientifically valid by, inter alia, showing that the evidence grew out of pre-litigation research, showing that the research upon which the evidence is based has been subjected to normal scientific scrutiny through peer review and publication, or explaining precisely how the conclusions were reached and pointing to *717some objective source to show that the conclusions are based on “scientific method, as it is practiced by (at least) a recognized minority of scientists in the[ ] field.” Daubert II, 43 F.3d at 1318-19.
Southland Sod Farms v. Stover Seed Co., 108 F.3d 1134, 1141 (9th Cir.1997). Reliability of method may also be indicated by whether a method can be and has been tested, its known or potential rate of error, and its degree of acceptance within a relevant scientific community. Daubert, 509 U.S. at 593, 594, 113 S.Ct. at 2796, 2797.
If the proffered testimony indeed embodies knowledge, the trial court must determine whether that knowledge will “assist the trier of fact to understand the evidence or to determine a fact in issue,” i.e., whether it is helpful. Fed.R.Evid. 702. “This condition goes primarily to relevance. ‘Expert testimony which does not relate to any issue in the ease is not relevant and, ergo, non-helpful.’ ” Daubert, 509 U.S. at 591, 113 S.Ct. at 2795 (quoting 3 Jack Weinstein & Margaret Berger, Weinstein’s Evidence: United States Rules ¶ 702[02], at 702-18 (1988)). The question of helpfulness has been characterized as one of “fit.” “ ‘Fit’ is not always obvious, and scientific validity for one purpose is not necessarily validity for other, unrelated purposes.” Id. Rather than asking “what do you know?”, the latter inquiry asks “how does it help?”
Rule 702 recognizes that a witness may be an expert, and that a witness may have an opinion, but that it may not be an expert opinion, and may not be helpful to the trier of fact.
Webb asserts that Daubert governs the admissibility of expert testimony regarding the modus operandi of criminals. The majority rejects Webb’s assertion because “the Daubert standards for admission simply do not apply” to “specialized knowledge of law enforcement, not scientific knowledge.”1
Yet Rule 702 applies to all expert testimony and requires the trial court to determine at the outset, pursuant to Rule 104(a), whether the witness is proposing to testily to “scientific, technical, or other specialized knowledge” and whether the witness is qualified as an expert by “knowledge, skill, experience, training, or education.” Then, as gatekeeper, the trial court “must ensure that the proposed expert testimony is relevant to the task at hand,” Daubert II, 43 F.3d at 1315.
This “gatekeeper” function finds description in Daubert, but it finds its source in Rule 702. Rule 702 makes the trial judge no less the gatekeeper when counsel characterizes proffered expert testimony as “technical” or “specialized,” rather than “scientific.” '
In saying that “the Daubert standards for admission simply do not apply” to “specialized knowledge of law enforcement,” we cannot be suggesting that the district court examine less rigorously the specialized knowledge underlying proffered nonscientific testimony, or that the district court may abdicate its role as gatekeeper where the subject matter does not depend upon the scientific method. The trial court’s role as gatekeeper concerning nonscientific “specialized knowledge” proves equally crucial to the integrity of the trial process, particularly where, as here, the proffered testimony’s potential for prejudice to the defendant runs so high.
Daubert and “Specialized Knowledge”
Daubert suggests that the term “knowledge” itself “connotes more than subjective belief and unsupported speculation. The term ‘applies to any body of known facts or to any body of ideas inferred from such facts *718or accepted as truths on good grounds.’” 509 U.S. at 590, 113 S.Ct. at 2795 (quoting Webster’s Third New International Dictionary 1251 (1986)). In evaluating the admissibility of testimony as to technical or other specialized knowledge, the trial court in each instance must examine whether what is proffered as knowledge truly deserves the label, and must ask “does this particular expert have sufficient specialized knowledge to assist the jurors in this case?” 3 Jack Wein-stein & Margaret Berger, Weinstein’s Evidence: United States Rules ¶ 702[01], at 702-9 (1995).
Daubert offers some general observations concerning the factors bearing upon the inquiry whether the reasoning or methodology underlying proffered testimony as to “scientific knowledge” is scientifically valid, i.e., that it is “derived by the scientific method.” 509 U.S. at 590, 113 S.Ct. at 2795. See id. at 593-94, 113 S.Ct. at 2796-97.2 Similar factors pertaining to the validity of “technical or other specialized knowledge” have not yet found a comparable catalogue in the reported cases.3 Nevertheless, “the trial judge cannot ... make a determination as to admissibility without investigating the competence the particular proffered expert would bring to bear on the issues. Only then will the judge be able to decide whether the test of Rule 702-assistance to the trier of fact-has been satisfied.” 3 Weinstein & Berger ¶ 702[04], at 702-60. Looking beyond the general qualifications of a witness, the recurring question “Does a person generally qualified in a field have sufficient specific knowledge to deal with the particular issues in the case at hand?” must be resolved in the first instance by the trial judge. Id. at 702-61 to 702-62, 702-75. Cf. Minasian v. Standard Chartered Bank, PLC, 109 F.3d 1212, 1216 (7th Cir.1997) (proffered banking expert “did not gather any data on the subject, survey the published literature, or do any of the other things that a genuine expert does before forming an opinion”).
Specialized Knowledge: “What does he know?”
In this instance, Detective Navarro’s expert testimony ostensibly involved “specialized knowledge of law enforcement,” or more precisely, specialized knowledge of human behavior patterns characteristic of the ongoing illicit concealment of firearms-“where, how, and why criminals conceal their weapons.”4 Detective Navarro testified to his training and experience “in the way that guns are sometimes concealed in ears,” including approximately a year of interviews with inmates of the Los Angeles County Jail, some of whom discussed concealing weapons in the engine compartment of cars and the reasons for doing so.
Assisting the trier of fact: “How does it help?”
Judge Trott writes that Detective Navarro’s testimony “explained evidence about the gun’s whereabouts that easily could have been beyond the knowledge of a normal juror.” But what was it about the evidence that a gun was concealed in the engine compartment of Webb’s car that the expert helped the jury to understand? This was not a case in which the expert explained the criminal purpose of seemingly innocuous acts. Indeed, the majority concedes that the fact that a gun was concealed under the hood of Webb’s car “was by no means innocuous,” but says the testimony nevertheless was properly admitted “to assist the jury in understanding the reasons why a person would conceal a weapon in the engine compartment *719of a ear,” such as “to avoid arrest or prosecution.” Yet “why” the gun was concealed was not an element of the charged offense, and not “a fact in issue” for purposes of Rule 702.
How, then, does it help?
The majority asserts that the Government used the expert’s testimony “to rebut Webb’s lack of knowledge claim,”5 yet notes that Detective Navarro never offered any opinion about whether Webb knew the weapon was hidden in his ear. Rather, the witness “described a typical situation,” and “a typical way people conceal weapons in ears and the typical reasons for their concealment.” If, as the majority acknowledges, the expert admitted that he had “no information that Webb knew the weapon was in the engine compartment,” how could he assist the jury in determining whether Webb did know?
Detective Navarro’s testimony implicitly suggested that Webb knew-the inference of knowledge being drawn from the fact of concealment because knowing concealment was typical of the other criminals with whom Detective Navarro was acquainted. If expert testimony that “people” conceal firearms in the engine compartment of their cars to avoid arrest and prosecution was “probative of Webb’s knowledge of the gun’s presence,” then Webb’s guilty knowledge flowed by inference from the guilty knowledge of nameless others. Only in this fashion could the expert “rebut Webb’s lack of knowledge claim” while testifying to no specific knowledge or opinion as to whether Webb himself knew about the gun.
Webb’s objection that he was improperly “profiled” by the Government’s expert does not stray too far off the mark.6 Cf. United States v. Gillespie, 852 F.2d 475, 479-80 (9th Cir.1988) (district court abused discretion in admitting expert testimony by clinical psychologist describing the common characteristics of child molesters).
This court has long been critical of the use of profile evidence-proof of what is “typical”as substantive evidence of guilt, insisting that “ ‘... [ejvery defendant has a right to be tried based on the evidence against him or her-’” United States v. Beltran-Rios, 878 F.2d 1208, 1210 (9th Cir.1989) (quoting United States v. Hernandez-Cuartas, 717 F.2d 552, 555 (11th Cir.1983)). In rejecting Webb’s “profile” objection, the majority characterizes the expert testimony in this case as going to' modus operandi7 rather than a profile.
*720Rule 702 and Modus Operandi Evidence
In prior cases this court has addressed two types of modus operandi evidence: (1) evidence of an individual modus operandi, or “signature” evidence;8 and (2) evidence of a common modus operandi, shown by testimony as to “the general practices of criminals,” which ostensibly “helps the jury to understand complex criminal activities, and alerts it to the possibility that combinations of seemingly innocuous events may indicate criminal behavior.” United States v. Johnson, 735 F.2d 1200, 1202 (9th Cir.1984). This court has approved of the use of expert testimony concerning a common modus oper-andi on a number of occasions. See United States v. Gil, 58 F.3d 1414 (9th Cir.1995), cert. denied, — U.S.-, 116 S.Ct. 430, 133 L.Ed.2d 345 (1995).9 The ostensible purpose of this kind of testimony is to “alert the jury to the possibility that combinations of seemingly innocuous events may indicate criminal behavior.” United States v. Lui, 941 F.2d 844, 848 (9th Cir.1991).10 “Expert testimony on the structure of criminal enterprises is allowed to help the jury understand the scheme and assess a defendant’s involvement in it.” United States v. Patterson, 819 F.2d 1495, 1507 (9th Cir.1987) (expert testimony “helped the jury understand the complex heroin distribution scheme”).11 Moreover, “In a series of cases, we have upheld admission of a law enforcement officer’s expert testimony that the defendant’s activities indicated that he acted in accordance with usual criminal modus operandi.” United States v. Espinosa, 827 F.2d 604, 612 (9th Cir.1987) (upholding introduction of expert testimony regarding use of apartment as a “stash pad”), cert. denied, 485 U.S. 968, 108 S.Ct. 1243, 99 L.Ed.2d 441 (1988).
While “modus operandi” evidence may be admitted to help the jury understand corn-*721plex criminal activities, this court has also recognized the need for caution. United States v. Gutierrez, 995 F.2d 169 (9th Cir.1993), another gun possession ease, acknowledged the admissibility of common modus operandi evidence in affirming the admissibility of a police officer’s expert opinion that a defendant’s observed actions were “furtive,” but warned:
Nonetheless, a trial court should not routinely admit this type of opinion testimony without carefully weighing the testimony’s probative value against its possible prejudicial effect.... “This weighing is particularly important with the expert testimony of a law enforcement officer, which often carries an aura of special reliability and trustworthiness.” Id. at 613 (internal quotations omitted).
Id. at 172 (quoting United States v. Espinosa, 827 F.2d at 613).12 Likewise, a trial court should not routinely admit this type of expert testimony without making the threshold determinations concerning specialized knowledge and helpfulness required by Rule 702.13 See also Peter Schofield, Note, Criteria for Admissibility of Expert Opinion Testimony on Criminal Modus Operandi, 1978 Utah L.Rev. 547.
The prior eases in this circuit discussing common modus operandi testimony often discuss helpfulness in connection with the complexity of the criminal activities at issue. See, e.g., Cordoba, 104 F.3d at 230 (“the testimony was properly admitted to assist the jury in understanding modus operandi in a complex criminal ease”); Lim, 984 F.2d at 335; Lui 941 F.2d at 847-48; Johnson, 735 F.2d at 1202 (“Such evidence helps the jury to understand complex criminal activities ”). The more' complex the pattern of criminal behavior at issue, the more assistance it would seem an expert could offer in explaining the significance of particular elements of the pattern.
The problem here is that concealing a firearm in a vehicle does not appear to present a “complex criminal ease.”
Far from being innocuous, a gun in an engine compartment seems entirely out of place. Common sense urges the inference that a person who conceals a. gun in an engine compartment knows that the gun is there. While reinforcing that simple inference, expert testimony that other persons who concealed guns in engine compartments did so knowingly offers little else that will assist the trier of fact. Why a gun may be concealed in a vehicle’s engine compartment, e.g., to avoid detection, seems almost as apparent.
United States v. Booth, 669 F.2d 1231 (9th Cir.1981), affirmed the trial court’s exclusion of expert testimony concerning the absence of fingerprints in a bank robbery get-away vehicle because of the government’s failure to make a preliminary showing (1) that the witness had expert knowledge of the reason no fingerprints were found on the vehicle and (2) that the testimony would be helpful: “The court found this testimony was irrelevant because, in the absence of any showing by the government that this was Booth’s modus operandi, it did not tie Booth to the robbery.” Id. at 1240. Moreover, “[t]he trier of fact is capable of inferring why no fingerprints were *722found without the assistance of expert testimony.” Id.
While this is not to say that expert testimony must be excluded in cases where the subject-matter falls within the comprehension of the average juror,14 Rule 702’s helpfulness requirement indicates that the proffered testimony must offer something not otherwise present that would be helpful to the trier of fact. Cf. United States v. Castillo, 924 F.2d 1227, 1232-33 (2d Cir.1991).
Whether the situation is a proper one for the use of expert testimony is to be determined on the basis of assisting the trier. “There is no more certain test for determining when experts may be used than the common sense inquiry whether the untrained layman would be qualified to determine intelligently and to the best possible degree the particular issue without enlightenment from those having a specialized understanding of the subject involved in the dispute. Ladd, Expert Testimony, 5 Vand.L.Rev. 414, 418 (1952). When opinions are excluded, it is because they are unhelpful and therefore superfluous and a waste of time.
Fed.R.Evid. 702 advisory committee’s note.
Judge Trott seems to suggest that expert testimony from law enforcement officers concerning a common criminal modus operandi should be deemed admissible almost as a matter of routine, even in relatively simple eases.15 I am convinced that Rule 702 as amplified in Daubert requires trial courts as gatekeepers to engage in a more thoughtful, more deliberate process, testing specialized knowledge and helpfulness anew in each case.
In this case, the district court considered the admissibility of the proffered expert testimony in the context of a pretrial motion in limine, and as a preliminary matter allowed the testimony as helpful to show possession, noting that “[t]he government does have the burden of proving that the defendant knew the gun was there.” Though the district court’s ruling remains somewhat unclear on the precise issue of helpfulness, I am not persuaded the district court’s ruling in this instance was “manifestly erroneous.” Espinosa, 827 F.2d at 611. I therefore vote to affirm.

. The majority cites to United States v. Cordoba, 104 F.3d 225, 230 (9th Cir.1997), which similarly rejected the view that Daubert governs the admission of expert testimony regarding the modus operandi of narcotics traffickers, reasoning that "Daubert applies only to the admission of scientific testimony.... In order to qualify as scientific knowledge, an inference or assertion must be derived from the scientific method. The government expert testified on the basis of- specialized knowledge, not scientific knowledge.”
It appears that this court has spoken on this subject with more than one voice. See Southland Sod Farms, 108 F.3d at 1143 n. 8 (9th Cir.1997) ("Daubert’s holding applies to all expert testimony, not just testimony based on novel scientific methods”); Claar v. Burlington Northern R. Co., 29 F.3d 499, 501 n. 2 (9th Cir.1994) (Daubert’s requirements "apply to all proffered expert testimony-not just testimony based on novel scientific methods or evidence”).

. Perhaps it is these specific factors involving the scientific method which are "the Daubert standards of admission" which the majority in this case says “simply do not apply.”

. One commentary suggests that "courts must address the question of what threshold of reliability will be required of evidence which is determined to be 'technical, or other specialized knowledge’ to which Daubert does not apply.” 2 Michael H. Graham, Handbook of Federal Evidence § 702.5, at 98 (4th ed.1996).

. Are we so certain that knowledge of patterns of human behavior does not represent scientific knowledge, at least to some degree? Accurate description of patterns of human behavior requires empirical observation, perhaps even the formulation and testing of hypotheses concerning predictable relationships between different observed facts. Indeed, “there is no obvious clear demarcation between scientific knowledge and technical and other specialized knowledge.” 2 Graham, § 702.5, at 81.

. Defendant Webb did not testify at trial. In opening statement, Webb’s counsel asserted that the government "will not be able to prove to you, ladies and gentlemen, that he [Webb] knew that that gun was hidden in that car and that he intentionally and knowingly possessed that gun,” i.e., that the government would fail to meet its burden of proof as to an essential element of the charged offense. Hardly an affirmative claim, Webb offered no evidence concerning his knowledge-or lack thereof-to which the government properly could offer expert testimony in rebuttal. See 1 Graham, § 611.3, at 819 ("The proper scope and function of rebuttal is thus refutation, which involves evidence which denies, explains, qualifies, disproves, repels, or otherwise sheds light on evidence offered by the defense including evidence rehabilitating the credibility of witnesses.” (emphasis added & footnote omitted)).

. In Reid v. Georgia, 448 U.S. 438, 100 S.Ct. 2752, 65 L.Ed.2d 890 (1980) (per curiam), the Supreme Court described a “drug courier profile” as "a somewhat informal compilation of characteristics believed to be typical of persons unlawfully carrying narcotics.” Id. at 440, 100 S.Ct. at 2753 (emphasis added). "This court has repeatedly noted that the government may not use such profiles as evidence of substantive guilt.” United States v. Baron, 94 F.3d 1312, 1320 (9th Cir.1996); see, e.g., United States v. Ogbuehi, 18 F.3d 807, 812 (9th Cir.1994); United States v. Lim, 984 F.2d 331, 334-35 (9th Cir.), cert. denied, 508 U.S. 965, 113 S.Ct. 2944, 124 L.Ed.2d 692 (1993); United States v. Lui, 941 F.2d 844, 847 (9th Cir.1991). "The admission of drug courier profile evidence is inherently prejudicial to the defendant because the profile may suggest that innocuous events indicate criminal activity.” Lim, 984 F.2d at 334-35 (citing Lui, 941 F.2d at 848).

.Modus operandi-the “phrase of which authors of detective fiction are fond”-often refers to evidence of other criminal acts committed by the defendant "so nearly identical in method as to earmark them as the handiwork of the accused.” 1 McCormick on Evidence § 190, at 801 & n. 19 (John W. Strong ed., 4th ed.1992) (footnote omitted). “Much more is demanded than the mere repeated commission of crimes of the same class, such as repeated murders, robberies or rapes. The pattern and characteristics of the crimes must be so unusual and distinctive as to be like a signature.” Id. at 801-03 (footnotes omitted).

. In United States v. Momeni, 991 F.2d 493, 494 (9th Cir.1993), a prosecution for mail, wire and credit card fraud at hotels in Hawaii, the government presented "signature” evidence suggesting that each of the hotel stays involved the same individual, (e.g., the perpetrator gave the same fictitious address and/or fictitious telephone number; tips on credit card vouchers were in such amounts that the totals rounded off to even dollar amounts, the perpetrator departed prior to the scheduled end of his stay without checking out). “Evidence of this kind may be sufficient alone to establish a perpetrator’s identity. See United States v. Milhollan, 599 F.2d 518, 524-25 (3d Cir.1979) (finding similar modus operandi evidence probative of identity); 2 Jack B. Wein-stein & Margaret A. Berger, Weinstein’s Evidence ¶ 404[16] (1992) (discussing "signature” evidence in context of Fed.R.Evid. 404(b)).” See also Featherstone v. Estelle, 948 F.2d 1497 (9th Cir.1991) (holding that admission of testimony which denominated appellant's modus operandi in previously uncharged and charged crimes was not clearly erroneous).
Evidence of individual modus operandi may be admissible under Fed.R.Evid. 404(b), inter alia, to show absence of mistake or accident, or to show knowledge or intent. See United States v. Hinton, 31 F.3d 817, 822-23 (9th Cir.1994); United States v. Ramirez-Jiminez, 967 F.2d 1321, 1325-27 (9th Cir.1992) (evidence of prior similar conduct was relevant as tending to show that defendant was aware or at least in reckless disregard of fact that truck that he subsequently drove contained illegal aliens in strikingly similar mo-dus operandi).

. See also United States v. Kearns, 61 F.3d 1422 (9th Cir.1995); United States v. Gomez-Osorio, 957 F.2d 636, 641-42 (9th Cir.1992) (admitting expert testimony that defendant’s use of pagers indicated he was a money launderer); United States v. Jaramillo-Suarez, 950 F.2d 1378, 1384 (9th Cir.1991) (expert testimony that pagers used frequently in drug trafficking was relevant evidence); United States v. Stewart, 770 F.2d 825, 831 (9th Cir.1985), cert. denied, 474 U.S. 1103, 106 S.Ct. 888, 88 L.Ed.2d 922 (1986) (counter surveillance driving); United States v. Rogers, 769 F.2d 1418, 1425 (9th Cir.1985) (”[l]aw enforcement officers may testify concerning the techniques and methods used by criminals.”).

. See also United States v. Alonso, 48 F.3d 1536, 1541 (9th Cir.1995) (reviewing cases and concluding that ”[t]hese cases show that a district court may properly allow expert testimony from a law enforcement officer that will help the juiy understand how otherwise innocent conduct ... might in fact be consistent with or even indicative of criminal conduct”).

. See also United States v. Taren-Palma, 997 F.2d 525, 534-35 (9th Cir.1993), cert. denied, 511 U.S. 1071, 114 S.Ct. 1648, 128 L.Ed.2d 368 (1994); United States v. Lockett, 919 F.2d 585, 590-91 (9th Cir.1990) (role of participants in drug trafficking organization); United States v. Mares, 940 F.2d 455 (9th Cir.1991); United States v. Bosch, 914 F.2d 1239, 1242-43 (9th Cir.1990) (role of defendant in aiding and abetting narcotics distribution); United States v. Andersson, 813 F.2d 1450 (9th Cir.1987); United States v. Fleishman, 684 F.2d 1329 (9th Cir.), cert. denied, 459 U.S. 1044, 103 S.Ct. 464, 74 L.Ed.2d 614 (1982).

. In contrast to the majority, I am not so certain that this circuit has rejected the argument that modus operandi expert testimony raises concerns similar to those raised by drug-profile testimony.

. The district court retains its role as gatekeeper even if a law enforcement officer’s testimony is to be received as lay opinion testimony under Fed.R.Evid. 701. In United States v. VonWillie, 59 F.3d 922, 929 (9th Cir.1995), this court held that a law enforcement officer’s testimony concerning the nexus between drug trafficking and weapons possession
was rationally based on his perceptions during the search at VonWillie's residence and his perceptions during prior drug investigations. See Fed.R.Evid. 701(a). His testimony also was helpful to the jury’s "determination of a fact in issue," see Fed.R.Evid. 701(b), namely whether VonWillie was involved in drug trafficking and whether he used a firearm "in relation to” a drug offense. See [United States v.] Simas, 937 F.2d [459] at 464-65 [ (9th Cir.1991) ] (the opinion of a law enforcement officer, who testified as a lay witness,” that the defendant's activities match ‘the usual criminal modus operandi,’ " is helpful to the jury and permissible under Rule 701(b)) (citation omitted).’’

. See 3 Weinstein & Berger ¶ 702[02], at 702-20 through 702-21.

. Judge Trott’s assertion that "we even allow modus operandi expert testimony in cases that are not 'complex’ ” finds little direct support in United States v. Gil, or in the other cases cited. Gil affirmed the admissibility of expert testimony conceming modus operandi of drug trafficking as “precisely the type [of conduct] for which modus operandi evidence is often used,” rejecting the defendants’ argument in Gil that "the activities described are not complex ones requiring expert explanation.” 58 F.3d at 1422.