FOR PUBLICATION

UNITED STATES COURT OF APPEALS

FOR THE NINTH CIRCUIT

UNITED STATES OF AMERICA, 

No. 11-30120 Plaintiff-Appellant,

D.C. No.

v.  3:10-cr-00069-

JENNIFER ANNE THOMS; TRACE RAE JWS-JDR-1

THOMS,

OPINION Defendants-Appellees. 

Appeal from the United States District Court

for the District of Alaska

John W. Sedwick, District Judge, Presiding

Argued and Submitted

May 10, 2012—Seattle, Washington

Filed June 29, 2012

Before: Ronald M. Gould, Jay S. Bybee, and Carlos T. Bea,

Circuit Judges.

Opinion by Judge Bea

7693
COUNSEL

Kirby Heller (argued), United States Department of Justice,

Appellate Section, Criminal Division, Washington, D.C.; Jo

UNITED STATES v. THOMS 7695
Ann Farrington and Stephan A. Collins, United States Department of Justice, Office of the United States Attorney, Anchorage, Alaska, for the plaintiff-appellant.

George J. Dozier, Jr. (argued) and Rex Lamont Butler, Rex

Lamont Butler and Associates, Anchorage, Alaska, for

defendant-appellee Trace Thoms.

Vikram N. Chaobal, Law Office of Vikram N. Chaobal,

Anchorage, Alaska, for defendant-appellee Jennifer Thoms.

OPINION

BEA, Circuit Judge:

In a criminal pre-trial matter, it is well established in our

circuit and in most others that, if a district judge is inclined

to depart from credibility findings of a magistrate judge that

were favorable to the defendant, he may only do so after holding a de novo evidentiary hearing. See United States v. Ridgway, 300 F.3d 1153 (9th Cir. 2002). This right is grounded in

the Due Process Clause. Id. at 1155-56. 

But what about the reverse? What if a magistrate judge recommends denying a motion to suppress, but the district judge

wishes to reverse that determination because he is inclined to

disbelieve the testimony of government officials? In that case,

must he hold a de novo hearing for the benefit of the government, which is the plaintiff in a criminal case?

This appeal considers such a case, and our circuit has yet

to address this question. The government primarily urges us

to adopt a broad rule: the government’s right to a de novo

hearing before a district judge is identical to that of defendants, even though the government cannot directly invoke the

protections of the Due Process Clause. The defendants

7696 UNITED STATES v. THOMS
counter that, without the Due Process Clause to ground this

right, the decision to hold a de novo hearing in such cases is

entirely within the district judge’s discretion. 

We disagree with both of those categorical options, and

today we adopt a middle ground, though our rule counsels

strongly in favor of holding a de novo hearing. We agree with

the defendants that the government does not have an unqualified right to a de novo evidentiary hearing whenever a district

judge reverses a magistrate judge’s credibility determinations

in a way adverse to the government. But we also agree with

the government that its interest in the integrity and accuracy

of judicial proceedings—which, after all, similarly underlie a

defendant’s due process rights to such a de novo hearing—

will often counsel in favor of such a hearing. Thus, we hold

that a district court abuses its discretion when it reverses a

magistrate judge’s credibility determinations, made after

receiving live testimony and favorable to the government,

without viewing key demeanor evidence, with one exception:

where the district judge finds that the magistrate judge’s credibility determinations had no legally sufficient evidentiary

basis, so that, were they jury determinations, judgment as a

matter of law would issue for the defendant.1

I.

Although the government’s appeal challenges only the procedure by which the district court rejected the credibility

determinations of the magistrate judge, and not the merits of

1By using the term “judgment as a matter of law,” we mean to incorporate the general standards of Federal Rule of Civil Procedure 50(a)(1),

which states: “If a party has been fully heard on an issue during a jury trial

and the court finds that a reasonable jury would not have a legally sufficient evidentiary basis to find for the party on that issue, the court may . . .

resolve the issue against the party.” We recognize that the analogy is not

perfect, as juries do not decide the pre-trial motions which we address

here, but the value of importing that standard to this context is that it is

a standard with which district courts will be quite familiar. 

UNITED STATES v. THOMS 7697
the district court’s decision to suppress the evidence, some

understanding of the events leading to this dispute is necessary.

A.

On February 22, 2010, an Alaska state judge issued a warrant to search a residential house and outbuildings located in

Wasilla, Alaska. The property is owned by defendants Trace

and Jennifer Thoms. The warrant was issued on the basis of

an affidavit submitted by Investigator Kyle Young, an Alaska

state trooper, whose affidavit provided probable cause for the

judge to conclude that the property’s owners could be growing marijuana on the property. 

The affidavit contained a variety of facts in support of the

warrant, but, for purposes of this appeal, the key piece of

information was Investigator Young’s claim that overnight on

February 21-22, 2010, he “smelled a strong odor of cultivating marijuana while driving on West Scarlett Circle, off of

Scarlett Drive in Wasilla.” He then said that “I immediately

stopped my vehicle and checked the wind direction and noted

that I was downwind of the first residence on the right on

West Scarlett Circle, off of Scarlett Drive.” Investigator

Young parked his car and walked on the roadway a short distance, and he continued to smell marijuana. In the affidavit,

he concluded that “Based upon the odor of marijuana in the

proximity of the suspect residence and the wind direction at

the time, I believe that the source of the odor was the first residence on the right on Scarlett Circle, described above.”

Investigator Young later estimated that he was approximately

400 to 600 feet away from the odor’s source when he first

smelled the marijuana. 

The state court judge approved the warrant, and officers

soon executed it and searched the property. There, in two outbuildings, police found a large marijuana grow operation,

consisting of around 400 plants. Later, co-defendant Trace

7698 UNITED STATES v. THOMS
Thoms testified to the many measures he took to contain the

smell emanating from the building with the growing plants.

This included insulating and taping the garage doors, installing two filtration systems, and even “ma[king] a conscious

effort to grow marijuana that was less odorous.” Thoms

expressed confidence that these protections would shield his

operation from law enforcement. “So were you able to sleep

at night knowing you had these filtration systems?” asked the

prosecutor. “I slept great,” Thoms replied. 

B.

Nonetheless, on July 23, 2010, the Thomses were indicted

on federal drug charges in the District of Alaska. The superseding indictment charged the Thomses with one count of

conspiracy to manufacture marijuana; one count of manufacturing marijuana; one count of maintaining a place for the

manufacture of marijuana; one count of conspiracy to commit

money laundering; and fourteen counts of money laundering.

The superseding indictment also contains allegations of criminal forfeiture against some of Thomses property and possessions. 

The Thomses moved to suppress the evidence of the search,

and they requested a Franks hearing to challenge the truth of

the statements in Investigator Young’s affidavit. Under

Franks v. Delaware, 438 U.S. 154 (1978), and its progeny, a

defendant can challenge the truth of police statements contained in an affidavit in support of a search warrant. Under

Franks, suppression is appropriate only where a defendant

proves that “that the magistrate or judge in issuing the warrant

was misled by information in the affidavit that the affiant

knew was false or would have known was false except for his

reckless disregard of the truth.” United States v. Stanert, 762

F.2d 775, 780 (9th Cir. 1985). Thus, to prevail on this claim,

the Thomses were required to show that Investigator Young’s

statements in the affidavit were deliberate or reckless falseUNITED STATES v. THOMS 7699
hoods. The matter was referred to a magistrate judge, who

granted the request to hold a Franks hearing. 

At the hearing, ten witnesses testified over the course of

two days. Seven witnesses testified on behalf of the Thomses,

including Trace Thoms and Professor Richard Doty, the

director of the Smell and Taste Center at the University of

Pennsylvania School of Medicine. Three witnesses testified

on behalf of the government: Investigator Young, and two

other officers involved in the search.

In a detailed report and recommendation, the magistrate

“conclude[d] that the testimony at the Franks hearing does

not show recklessness by Inv. Young nor does it prove the

officer perjured himself when he claimed he smelled marijuana.” The magistrate therefore recommended denying the

motion to suppress. 

The Thomses filed objections to the magistrate’s report,

and the district court reversed the magistrate’s recommendation and granted the motion to suppress. The district court did

so without holding a de novo evidentiary hearing to hear any

live testimony. Instead, the district court conducted a de novo

review of the facts and the law based on the entire record,2

including the hearing transcript, and the district court concluded that a preponderance of the evidence at the Franks

hearing showed that Investigator Young’s claim that he

smelled marijuana from his location was not credible. The

court said:

To conclude that Investigator Young did smell marijuana from the road, while in his vehicle would

require the court to assume that Thoms’ filtration

2As discussed further infra, 28 U.S.C. § 636(b) specifies that a district

judge “shall make a de novo determination of those portions of the report

or specified proposed findings or recommendations to which objection is

made.” 

7700 UNITED STATES v. THOMS
system was either saturated or not functional; that

the odor of marijuana left the outbuilding unfiltered

and remained warm long enough to stay above the

vegetation behind the Thomses’ house;[3] that it

either traveled around the Thomses’ two-story residence or stayed warm long enough to traverse above

it then suddenly dropped in the area Young claimed

to smell marijuana; and that it followed the described

450 foot course without dispersing beyond perceptible levels. Those assumptions are contrary to a preponderance of the evidence presented at the Franks

hearing. 

Because a “district court must suppress evidence seized under

a warrant when an affiant has knowingly or recklessly

included false information in the affidavit,” United States v.

Dozier, 844 F.2d 701, 705 (9th Cir. 1988) (emphasis added),

and the good faith exception did not apply, the district court

granted the motion to suppress. 

C.

The government filed a motion to reconsider. The government requested reconsideration solely on procedural grounds.

Namely, the government contended that the district court was

required to conduct a de novo evidentiary hearing before

rejecting the magistrate’s credibility determinations.

The district court denied the government’s motion. The district court acknowledged that when a district court reverses a

magistrate judge’s credibility findings in a manner adverse to

a defendant, a de novo hearing is required on due process

grounds. But “[b]ecause a defendant’s due process rights are

not at issue when a motion to suppress is granted over a magistrate judge’s recommendation, a de novo evidentiary hearing

3The record shows that the outbuilding is set back from the street, and

that between the street and the outbuilding there are many trees. 

UNITED STATES v. THOMS 7701
is not necessarily required.” The district court noted that it

had reviewed de novo the entire record and “explained at

length how the evidence presented renders it highly improbable (indeed, it seems to this court in light of all the evidence,

virtually impossible) that Investigator Young could smell the

marijuana grow under the circumstances that existed at the

time.” Moreover, “[t]hat conclusion would not change simply

because this court heard the evidence all over again.” 

The government timely appealed the district court’s orders

denying reconsideration and granting the motion to suppress.

II.

We have jurisdiction to review this interlocutory appeal

from a district court’s grant of a motion to suppress under 18

U.S.C. § 3731. Whether the government has a legal right to

a de novo hearing is a question of law, and we review questions of law de novo. See Movsesian v. Victoria Versicherung

AG, 670 F.3d 1067, 1071 (9th Cir. 2012) (en banc).

III.

The sole question presented is under what circumstances, if

any, a district judge may reject a magistrate judge’s credibility

finding without holding a new hearing, when the magistrate

recommends denying a motion to suppress and the district

court refuses to adopt the recommendation and grants the

motion to suppress. In resolving this question, we first address

the government’s argument that precedent requires a district

court to hold a new hearing in all such circumstances. We disagree with this categorical proposition. However, we may also

look to our supervisory authority and inquire whether a more

limited rule suggesting a de novo hearing in many circumstances would be “desirable from the viewpoint of sound judicial practice although in nowise commanded by statute or by

the Constitution.” Thomas v. Arn, 474 U.S. 140, 146-47

(1985) (emphasis added) (internal quotation marks omitted).

7702 UNITED STATES v. THOMS
We conclude that such a rule is desirable. Thus, we vacate the

district court’s suppression and reconsideration orders and

remand to reconsider the issue with the new rule in mind.

A.

[1] The relevant section of the Federal Magistrates Act, 28

U.S.C. § 636(b)(1), allows a magistrate judge to conduct an

evidentiary hearing on a motion to suppress and make recommendations to a district judge. Then, 

Within fourteen days after being served with a copy

[of the magistrate’s report], any party may serve and

file written objections to such proposed findings and

recommendations as provided by rules of court. A

judge of the court shall make a de novo determination of those portions of the report or specified proposed findings or recommendations to which

objection is made. A judge of the court may accept,

reject, or modify, in whole or in part, the findings or

recommendations made by the magistrate judge. The

judge may also receive further evidence or recommit

the matter to the magistrate judge with instructions.

Id. The Supreme Court has said that it is “clear” from this text

that “the statute calls for a de novo determination, not a de

novo hearing.” United States v. Raddatz, 447 U.S. 667, 674

(1980). Thus, it is undisputed the government has no right

under the statute to require the district judge to hold a de novo

hearing when he “accept[s], reject[s], or modif[ies]” the magistrate’s recommendation. 

[2] But despite the broad language of the statute, the district court’s discretion either to hold or refuse to hold a new

hearing when considering a magistrate’s recommendation is

not unbounded. Rather, this court has said that “a district

court errs when it does not conduct a de novo evidentiary

hearing if it rejects the credibility finding of a magistrate

UNITED STATES v. THOMS 7703
judge who recommends the granting of a motion to suppress.”

Ridgway, 300 F.3d at 1157 (emphasis added). The critical

question, then, is the source of law for the categorical rule for

which the government advocates here. If the Ridgway rule is

based solely upon a defendant’s due process rights, then it is

an asymmetrical right because, as the government admits,

“the government does not share a defendant’s right to due process.”4

 But if that right inheres in all litigants’ right to the “integrity and accuracy of the fact-finding process,” United

States v. Bergera, 512 F.2d 391, 393 (9th Cir. 1975), then the

logic requiring a de novo hearing for defendants necessarily

is symmetrical and requires a district court to conduct a de

novo hearing whenever it rejects a magistrate’s credibility

findings. 

A careful reading of our caselaw formally grounds this

right in the Due Process Clause, and therefore the government

does not have a categorical right to a de novo hearing whenever a district judge disagrees with a magistrate judge’s credibility determinations and accompanying recommendation that

a motion to suppress be denied. However, as we note below

in subsection B, the interests recognized in these due process

cases are shared by all litigants. Thus, a similar but more limited rule is appropriate for this case. 

United States v. Bergera, the case on which the government

most heavily relies, is the earliest in the key trio of cases in

this area. In Bergera, the defendants were indicted for possession with intent to distribute marijuana after police found

4The Due Process Clause of the Fifth Amendment states that “[n]o person shall be . . . deprived of life, liberty, or property without due process

of law.” U.S. Const. amend. V; see also id. amend. XIV (“[N]or shall any

State deprive any person of life, liberty, or property, without due process

of law . . . .”). The Supreme Court has stated that “[t]he word ‘person’ in

the context of the Due Process Clause of the Fifth Amendment cannot, by

any reasonable mode of interpretation, be expanded to encompass the

States of the Union.” South Carolina v. Katzenbach, 383 U.S. 301, 323

(1966). 

7704 UNITED STATES v. THOMS
drugs in the defendants’ garage, bedroom, closets, kitchen,

and Volkswagen bus. 512 F.2d at 392. The defendants moved

to suppress the marijuana from admission into evidence, and

the matter was referred to a magistrate for an evidentiary

hearing. Id. After the hearing, the magistrate recommended

granting the motion, but, without holding a new hearing, the

district court reversed. Id.

We reversed. We explained our rationale not in terms of

due process but in terms of the integrity and accuracy of the

judicial process generally:

Since the magistrate sees and hears the evidence, the

district court is entitled to rely upon his recommendations when making its decision on the motion. If,

however, the district court chooses to reject the recommendation of the magistrate, it must itself hear

the testimony and see the evidence before deciding

the motion. Permitting the district court to simply

review dry records or listen to tape recordings of the

evidentiary hearing conducted by the magistrate

would not satisfy the high standard which must be

set for factual determinations which by themselves

can decide the outcome of a criminal trial. The

defendant is entitled to the assurance that important

factual conclusions will be drawn from the testimony

and other evidence itself. That assurance is provided

if the district court decides the motion in accordance

with the recommendations of a judicial officer who

observed the evidence. It is certainly provided if the

district court sees and hears the evidence itself. But

it is just as certainly absent if the district court is

allowed to disregard the recommendation of the

magistrate and decide the motion only on the basis

of dry records and one dimensional tapes. Therefore

we hold that the district court erred when it set aside

the magistrate’s recommendation and ruled on the

UNITED STATES v. THOMS 7705
motion to suppress without hearing the evidence on

the motion itself.

Id. at 394. Were Bergera that last word on this topic, we

could conclude that the right to a full de novo hearing is

entirely symmetrical. Bergera’s concern with the “integrity

and accuracy of the fact-finding process” generally applies to

all who have a stake in the judicial process. Id. at 393. But

later decisions require us to recognize that its scope is limited.5

Five years after Bergera, the Supreme Court decided

United States v. Raddatz. In Raddatz, the defendant was

indicted for unlawfully receiving firearms, and he moved to

suppress incriminating statements he made to federal agents.

447 U.S. at 669-70. The matter was referred to a magistrate,

and both the defendant and the agents testified at a hearing.

Id. at 670-71. The magistrate recommended denying the

motion to suppress, and the district court accepted the recommendation and denied the motion to suppress without holding

a de novo hearing. Id. at 672. The defendant raised two contentions before the Supreme Court: first, that the Federal

Magistrates Act, newly amended in 1976, required a de novo

hearing, and, second, that the Due Process Clause requires a

de novo hearing.6Id. at 673, 677. The Court rejected both

claims. Id. at 676, 683-84. Raddatz’s interpretation of § 636,

the relevant portions of which have not been amended since

then, precludes the government from contending here that it

5Further, at the time of Bergera, the version of § 636 then in force was

broader, as it allowed district courts to promulgate rules whereby magistrates may be assigned duties “as are not inconsistent with the Constitution

and laws of the United States.” 28 U.S.C. § 636(b) (1970). The statute said

that “[t]he additional duties authorized by rule may include, but are not

restricted to . . . assistance to a district judge in the conduct of pretrial or

discovery proceedings in civil or criminal actions.” Id. The then-extant

statute made no mention of the procedure by which a district court is to

review a magistrate’s handling of a pretrial matter. 

6The defendant also raised a claim that § 636(b)(1) violated Article III,

but the Court rejected that claim and it is not at issue here. 

7706 UNITED STATES v. THOMS
is entitled to a de novo hearing on statutory grounds. We

therefore discuss only Raddatz’s constitutional holding.

The Court began with the proposition that “[t]he guarantees

of due process call for a hearing appropriate to the nature of

the case.” Id. at 677 (internal quotation marks omitted). The

Court thus undertook a due process balancing inquiry before

concluding that “the due process rights claimed here are adequately protected by § 636(b)(1).” Id. at 680. The Court then

added an important footnote at the conclusion of the due process section. The footnote reads, in full:

Neither the statute nor its legislative history

reveals any specific consideration of the situation

where a district judge after reviewing the record in

the process of making a de novo “determination” has

doubts concerning the credibility findings of the

magistrate. The issue is not before us, but we assume

it is unlikely that a district judge would reject a magistrate’s proposed findings on credibility when those

findings are dispositive and substitute the judge’s

own appraisal; to do so without seeing and hearing

the witness or witnesses whose credibility is in question could well give rise to serious questions which

we do not reach.

Id. at 681 n.7. Unfortunately, the Court did not specify the

nature of these “serious questions,” and it has not since Raddatz been presented with a case implicating them.

The final case in the trilogy is United States v. Ridgway.

Ridgway had relevant facts similar to Bergera. The defendant

was indicted on drug charges, and he filed a motion to suppress. 300 F.3d at 1154-55. The magistrate heard testimony,

disbelieved the Drug Enforcement Administration (“DEA”)

agent, and recommended granting the motion. Id. at 1155.

Without conducting a de novo hearing, the district court

rejected the adverse credibility finding, because the district

UNITED STATES v. THOMS 7707
court thought that inconsistencies in the DEA agent’s testimony were in fact “explained fully” during the agent’s crossexamination. Id. The defendant was convicted following a

bench trial. Id. On appeal, this court vacated the order denying the motion to suppress and remanded because “a district

court errs when it does not conduct a de novo evidentiary

hearing if it rejects the credibility finding of a magistrate

judge who recommends the granting of a motion to suppress.”

Id. at 1157.

[3] Ridgway’s reasoning is grounded in concepts of due

process. The Ridgway court began by noting that “[w]e

review de novo the question whether a defendant’s due process rights were violated.” Id. at 1155. Ridgway then explicitly gives Bergera a narrow reframing in light of Raddatz. The

Ridgway court said:

Although we held in Bergera that a district court is

required to conduct a de novo evidentiary hearing

before rejecting the factual determinations of a magistrate judge on a motion to suppress, we did not

frame this issue in terms of a due process violation.

In a case decided after we issued Bergera, however,

the Supreme Court [in Raddatz] addressed a related

issue and did frame its holding in terms of a defendant’s right to due process.

Id. at 1156. 

Ridgway’s holding is expressly limited to cases where a

defendant’s due process rights would be violated by the failure to hold a de novo evidentiary hearing. Moreover, Ridgway

says that Bergera must be read in light of the Supreme

Court’s Raddatz reframing of this issue in terms of due process. Thus, the precedent we are required to follow is limited

to the proposition that a defendant has a right to a de novo

hearing when the district court rejects the magistrate’s credibility findings that were favorable to the defendant. If the

7708 UNITED STATES v. THOMS
right to an evidentiary hearing prior to rejection of the magistrate’s credibility findings is based solely on the Due Process

Clause, the principle is not symmetrical: the government has

no right to a de novo evidentiary hearing in all circumstances

where a magistrate’s credibility determination is reversed, for

the government concedes it has no due process rights. See

supra p. 7704 and note 4. Further, in 2007, this court reaffirmed the narrower, asymmetrical view of Ridgway and Bergera when it said that “we reaffirmed in Ridgway that a

district court errs when it does not conduct a de novo evidentiary hearing if it rejects the credibility finding of a magistrate

judge who recommends granting a motion to suppress.”

United States v. Hernandez-Acuna, 498 F.3d 942, 944 (9th

Cir. 2007) (emphasis added) (citation omitted).

More recently, in Johnson v. Finn, 665 F.3d 1063 (9th Cir.

2011), our court encountered a case where the district court,

without holding a de novo hearing, reversed a magistrate’s

determination that a prosecutor had purposefully discriminated on the basis of race in exercising a peremptory strike of

a juror. Id. at 1065-66. We reversed. In so doing, we extended

the Ridgway rule to the Batson context, so that a defendant’s

due process rights are violated when a district court “declin[es] the opportunity to observe the trial prosecutor’s

demeanor before rejecting the magistrate judge’s adverse

credibility finding.” Id. at 1066. The court in Johnson noted

the importance of the general interest in accurate factfinding,

stating that a district judge who rejects a credibility determination without holding a de novo hearing is “hampered by the

deficiencies of a cold record.” Id. at 1073. The court then

reaffirmed Ridgway’s understanding of Raddatz by saying

that “the Raddatz footnote applies generally to determinations

affecting the rights of a criminal defendant and involving a

credibility finding.” Id. at 1074 (emphasis added). 

[4] From these repeated invocations of the Due Process

Clause, we can discern that the absolute right to have a de

novo hearing in all circumstances where a district court

UNITED STATES v. THOMS 7709
reverses a magistrate’s credibility findings belongs only to

defendants or others who may assert due process rights. Thus,

we decline to adopt the government’s proposed broad rule and

extend that line of precedent to all such determinations

adverse to the government.

B.

[5] But that does not end the matter. Our court has supervisory authority “to mandate procedures deemed desirable from

the viewpoint of sound judicial practice although in nowise

commanded by statute or by the Constitution.” Thomas, 474

U.S. at 146-47 (internal quotation marks omitted). The longstanding and repeated invocations in caselaw of the need of

district courts to hear live testimony so as to further the accuracy and integrity of the factfinding process are not mere platitudes. Rather, live testimony is the bedrock of the search for

truth in our judicial system. After all, “[w]here an unresolved

factual dispute exists, demeanor evidence is a significant factor in adjudging credibility.” Townsend v. Sain, 372 U.S. 293,

322 (1963), overruled on other grounds by Keeney v.

Tamayo-Reyes, 504 U.S. 1, 5-6 (1992); see also Anderson v.

City of Bessemer City, N.C., 470 U.S. 564, 575 (1985)

(“[O]nly the trial judge can be aware of the variations in

demeanor and tone of voice that bear so heavily on the listener’s understanding of and belief in what is said.”).

[6] To further the integrity and accuracy of our judicial

process and to facilitate the search for truth, we therefore

adopt a narrower rule than the one that applies where due process protections formally attach. We hold that a district court

abuses its discretion when it reverses a magistrate judge’s

credibility determinations, made after receiving live testimony

and favorable to the government, without viewing key demeanor evidence, with one exception: where the district judge

finds that the magistrate judge’s credibility determinations

had no legally sufficient evidentiary basis, so that, were they

jury determinations, judgment as a matter of law would issue

7710 UNITED STATES v. THOMS
for the defendant. So that district courts may apply this rule

practically, we turn to the rule’s application in the context of

this case. As applied here, we vacate and remand the district

court’s orders for reconsideration. 

[7] The district court noted that “in many cases, a district

court might need to conduct a second evidentiary hearing”

before departing from a magistrate judge’s credibility findings. But the district court failed to hold one for the following

reasons:

[T]his court has had access to a transcript of the

original evidentiary hearing and has explained at

length [in the previously quoted order] how the evidence presented renders it highly improbable

(indeed, it seems to this court in light of all the evidence, virtually impossible) that Investigator Young

could smell the marijuana grow under the circumstances that existed at the time. That conclusion

would not change simply because this court heard

the evidence all over again. The issue here does not

turn on the demeanor of the witnesses, but rather on

the implausibility of the officer’s conclusion that he

smelled the marijuana grow inside a sealed building

at least 450 feet away, which was screened by forest

vegetation and a hill with a house on it. These considerations, which are paramount in rendering

Young’s conclusion unbelievable, are either derived

directly from or are entirely consistent with Investigator Young’s own testimony. It would serve no purpose but delay to conduct a second hearing to hear

the testimony all over again. 

D. Ct. Order on Reconsideration 5 (emphasis removed) (footnote omitted). These considerations are not enough to overcome the strong presumption in favor of achieving integrity

and accuracy through hearing some live testimony anew

which we today adopt. The standard we import from Federal

UNITED STATES v. THOMS 7711
Rule of Civil Procedure 50 for judgment as a matter of law

in favor of Thoms was not met here. The evidence and testimony in favor of the Thomses was not so overwhelming that

the district court could have found, as a matter of law, that no

reasonable factfinder could have credited Investigator

Young’s testimony.

[8] In addition, the district court’s reasoning is speculative.

The district court stated that its “conclusion would not change

simply because this court heard the evidence all over again.”

But the district judge merely said that Young’s account was

“implausible” based on the cold record. Perhaps seeing Investigator Young’s demeanor as he testified to what he smelled

would have changed the outcome. The strong presumption in

our system is that demeanor evidence has important value. If

so, then the district judge’s certitude is misplaced. Surely,

there was some possibility the outcome would have been different had he heard live testimony. As one example, Investigator Young could have been testifying truthfully without

undermining any of the considerations important to the district court’s prior conclusion if the odor filtration system was

not working properly on the night Young said he smelled

marijuana. That it was working properly depended in part on

the evidence of the defendants, whose demeanor was not

observed by the district court. Or there might be other circumstances bolstering Young’s credibility that were not ruled out.

Moreover, the district court’s reasoning discounts the government’s interest in the “accuracy and integrity” of the factfinding process which, after all, is the foundation of the due

process right given defendants. Given the stated importance

of demeanor evidence in our system, the strong presumption

is that the government is entitled to proffer it for its most

important witnesses before a district judge reverses a magistrate’s credibility finding in favor of the government. Moreover, other stakeholders—like Investigator Young and other

similar law enforcement officials—also share this interest in

the integrity of the proceedings. In this case, just as in most

7712 UNITED STATES v. THOMS
cases where a district court grants a motion to suppress when

it rejects a magistrate’s credibility determination, the realworld consequence of the district court’s decision is that the

police officer was lying or recklessly disregarding the truth in

his warrant affidavit. There is a strong possibility that such a

finding could have serious professional, or even legal, consequences for Young. Yet the district judge discounted Investigator Young’s interest in presenting his demeanor to the

district court. Put another way, before a district court calls a

police officer a liar, there is a strong presumption that the

judge should look him in the eye first.

We recognize that not everyone agrees that demeanor evidence and live testimony are as important to the integrity and

accuracy of the judicial process as we think it is. The district

court stated on the record that live testimony would be useless

in this case. Others have gone further and argued that the

biases created by hearing live testimony can actually detract

from factfinding accuracy, and that these biases may be especially acute in the context of suppression motions. They note

that police officers testify frequently, are professionally

trained to remain calm in difficult circumstances, and come

with a professional reputation of trustworthiness. Defendants

have none of those advantages, and the “very thing the defendant seeks to suppress—evidence of criminal behavior—

suggests that he is less than an honest, upright citizen.” William J. Stuntz, Warrants and Fourth Amendment Remedies,

77 Va. L. Rev. 881, 914 (1991). Some think it likely that this

“credibility gap” can be lessened where a judge looks at a

cold record, since a cold record may permit the judge to focus

more on the substance of the testimony and less on witness

demeanor and appearance, which, at least in some circumstances, could be as misleading as they are helpful. “Perhaps,”

states a leading federal procedure treatise, “the entire American reliance on demeanor is misplaced.” Cf. 12 Charles Alan

Wright et al., Federal Practice & Procedure Civil § 3070.2

(2d ed.); see also id. at n.20 (“There is a considerable body

of psychological research indicating that in many contexts

UNITED STATES v. THOMS 7713
observing people tell stories does not enhance the ability to

determine whether the story is truthful, and may even corrupt

the ability to make accurate decisions about truthfulness.”).

We disagree, and do not think we overvalue the importance

of live testimony. For one thing, the Supreme Court and our

court have repeatedly cited the value of live testimony with

respect. Perhaps more importantly, trial judges and juries in

our circuit and all over the country rely on the demeanor evidence given by live testimony everyday, and they find it quite

valuable in making accurate decisions. Such testimony is in

fact indispensable, and the value of live, in-court testimony is

enshrined in the Sixth Amendment’s Confrontation Clause.

The value of live testimony is a large part of why our court

reviews district courts’ factual findings for clear error. Further, the value of live testimony also contributes to the need

for trial and disregard of summary judgment when there is a

genuine factual dispute on a relevant issue. Here, for instance,

we are in the same position as the district court with respect

to assessing the credibility of the witnesses who testified

before the magistrate. But only the district court has the

option of adding to that record through live testimony. That

is a great advantage, which district courts should take in most

cases before reversing credibility determinations. 

We do wish to highlight two limitations on the scope of our

rule. First, as we have stated, the rule we adopt today is not

completely equivalent to the absolute right to de novo hearings possessed by defendants. If the magistrate’s determination was so lacking in support that judgment as a matter of

law for the party who lost before the magistrate is appropriate,

a de novo hearing may not be in order. Having limited exceptions to the de novo hearing requirement where the government’s interests are at stake puts us in line with the other

circuits to have considered this issue. Both the Second and

Eleventh Circuits have stated de novo hearings are required in

most, but not all, circumstances where a magistrate judge’s

credibility findings are reversed to the detriment of the gov7714 UNITED STATES v. THOMS
ernment. See United States v. Cofield, 272 F.3d 1303, 1306

(11th Cir. 2001) (per curiam); Carrion v. Smith, 549 F.3d 583,

588 (2d Cir. 2008). The Thomses candidly admit that those

cases are on point, but they urge us to depart from the rule in

our sister circuits. We decline the invitation to create a circuit

split.

Second, the de novo hearing before the district judge need

not be a rerun of the entire hearing that occurred before the

magistrate. Here, ten witnesses testified before the magistrate

over the course of two days, including an expert witness who

is a professor at the University of Pennsylvania, in Philadelphia. Where the inefficiencies of hearing live testimony from

a witness greatly outweigh the value of seeing demeanor evidence, a district court can hold a more limited hearing than

that conducted by the magistrate. But here, as in many cases,

the key witnesses, Investigator Young and the defendants

likely live or work relatively near the courthouse. Further,

conducting a more limited hearing relieves the district court

of the heavy burden of entirely redoing the original hearing.

We leave it to the district court on remand to determine whose

live testimony it should hear to balance efficiency with the

integrity and accuracy interests we have described.

* * *

[9] In the business of judging, there is nothing more important than getting the facts right. In many cases, factual determinations are made after hearing live testimony regarding two

competing versions of critical events. To further the accuracy

and integrity of these determinations, we hold that a district

court abuses its discretion when it reverses a magistrate

judge’s credibility determinations, made after receiving live

testimony and favorable to the government, without viewing

key demeanor evidence, with one exception: where the district judge finds that the magistrate judge’s credibility determinations had no legally sufficient evidentiary basis, so that,

were they jury determinations, judgment as a matter of law

UNITED STATES v. THOMS 7715
would issue for the defendant. As applied to this case, we

VACATE the orders on suppression and reconsideration and

REMAND for further consideration. That consideration on

remand, we presume, will include a de novo hearing before

the district judge, but we leave it to the district court to determine the scope of that hearing.

VACATED and REMANDED.

7716 UNITED STATES v. THOMS