FOR PUBLICATION
UNITED STATES COURT OF APPEALS
FOR THE NINTH CIRCUIT
UNITED STATES OF AMERICA, No. 18-50120
Plaintiff-Appellee,
D.C. No.
v. 5:17-cr-00159-PA-1
PATRICK JOHN BACON,
Defendant-Appellant. OPINION
Appeal from the United States District Court
for the Central District of California
Percy Anderson, District Judge, Presiding
Submitted En Banc October 29, 2020*
San Francisco, California
Filed November 5, 2020
Before: Sidney R. Thomas, Chief Judge, and Richard A.
Paez, Marsha S. Berzon, Johnnie B. Rawlinson, Consuelo
M. Callahan, Mary H. Murguia, Andrew D. Hurwitz,
John B. Owens, Eric D. Miller, Bridget S. Bade and
Kenneth K. Lee, Circuit Judges.
Opinion by Chief Judge Thomas
*
The panel unanimously concludes this case is suitable for decision
without oral argument. See Fed. R. App. P. 34(a)(2).
2 UNITED STATES V. BACON
SUMMARY**
Criminal Law
The en banc court remanded to the three-judge panel for
a determination of the proper remedy in this criminal case in
which the three-judge panel held that the district court had
employed the incorrect legal standard for relevance under
Daubert v. Merrill Dow Pharmaceuticals, Inc., 509 U.S. 579
(1993), and Federal Rule of Evidence 702, when it excluded
testimony from the defendant’s proposed expert.
The Court voted to rehear the case en banc to consider
what the proper remedy is on appeal when this court
concludes that a district court has erred under Daubert by
admitting or excluding expert testimony on one ground, but
this Court cannot tell from the record whether the admission
or exclusion was nevertheless correct on other grounds.
Recognizing that there are different circumstances
involved in every case, the en banc court concluded that a
bright-line rule requiring a specific remedy is inappropriate.
Applying 28 U.S.C. § 2106, the en banc court held that when
a panel of this Court concludes that the district court has
committed a non-harmless Daubert error, the panel has
discretion to impose a remedy as may be just under the
circumstances. Restoring Daubert errors to the usual realm
of appellate review and remedy, the en banc court wrote that
circumstances may require a new trial in some instances and
dictate a limited remand in others. The en banc court
**
This summary constitutes no part of the opinion of the court. It has
been prepared by court staff for the convenience of the reader.
UNITED STATES V. BACON 3
overruled this Court’s prior case law to the extent it conflicts
with this opinion.
COUNSEL
Shaun Khojayan, Law Offices of Shaun Khojayan &
Associates P.L.C., Los Angeles, California, for Defendant-
Appellant.
Nicola T. Hanna, United States Attorney; L. Ashley Aull,
Chief, Criminal Appeals Section; Shawn T. Andrews, United
States Attorney; Violent and Organized Crime Section,
United States Attorney’s Office, Los Angeles, California; for
Plaintiff-Appellee.
Robert A. Olson, Greines Martin Stein & Richland LLP, Los
Angeles, California, for Amici Curiae Federation of Defense
and Corporate Counsel, Association of Southern California
Defense Counsel, and Association of Defense Counsel of
Northern California.
OPINION
THOMAS, Chief Judge:
We voted to rehear this case en banc to consider what the
proper remedy is on appeal when we conclude that a district
court has erred under Daubert v. Merrell Dow
Pharmaceuticals, Inc., 509 U.S. 579 (1993), by admitting or
excluding expert testimony on one ground, but when we
cannot tell from the record whether the admission or
exclusion was nevertheless correct on other grounds.
4 UNITED STATES V. BACON
Recognizing that there are different circumstances
involved in every case, we conclude that a bright-line rule
requiring a specific remedy is inappropriate. Instead, each
panel should fashion a remedy “as may be just under the
circumstances.” 28 U.S.C. § 2106. The remedy may include
remanding for a new trial or remanding for the district court
to first determine admissibility, then requiring a new trial
only if that admissibility determination differs from that in
the first trial. We remand this case to the three-judge panel
so that the panel may, in its discretion, determine the
appropriate remedy in this case.
I
The facts of the case are detailed in the panel opinion, so
we need not recount them here in any detail. See United
States v. Ray, 956 F.3d 1154, 1157–58 (9th Cir. 2020) (per
curiam). In brief, the district court excluded testimony from
Bacon’s proposed expert on the ground that the testimony
would be irrelevant under Daubert and Federal Rule of
Evidence 702. Id. at 1158. Because the district court’s
decision to exclude the testimony “start[ed] and end[ed] with
the question of relevance,” the court did not evaluate the
expert’s reliability. Id. at 1158–60; see also United States v.
Redlightning, 624 F.3d 1090, 1111 (9th Cir. 2010) (“The trial
judge must perform a gatekeeping function to ensure that the
expert’s proffered testimony is both reliable and relevant.”).
On appeal, the three-judge panel held, in a per curiam
opinion, that the district court had employed the incorrect
legal standard for relevance under Daubert and Rule 702
when it excluded the testimony. Ray, 956 F.3d at 1159–60.
The panel further determined that the error was not harmless.
Id. In ordering a remedy for the error, the panel concluded
UNITED STATES V. BACON 5
that it was bound by circuit precedent to vacate the conviction
and remand for a new trial. Id. at 1160–61 (citing United
States v. Christian, 749 F.3d 806, 814 (9th Cir. 2014)).
However, the entire panel joined a concurring opinion,
authored by Judge Watford, urging that we reconsider our
precedent and “conditionally vacate the judgment and remand
to the district court with instructions to determine whether the
disputed expert testimony was admissible pursuant to the
requirements of Rule 702 and Daubert.” Ray, 956 F.3d
at 1161 (Watford, J., concurring) (quoting Estate of Barabin
v. AstenJohnson, Inc. (“Barabin II”), 740 F.3d 457, 471 (9th
Cir. 2014) (en banc) (Nguyen, J., concurring in part and
dissenting in part)). The concurrence noted that the contested
expert testimony might again be excluded, this time on
reliability grounds, in which case the evidence in the second
trial would be the same as the evidence in the first trial. Id.
(“If that occurs, why in the world should the court hold a new
trial . . . ?”).
Upon an affirmative vote of a majority of the non-recused
active judges, we agreed to rehear this case en banc. United
States v. Ray, 974 F.3d 959 (9th Cir. 2020).
II
The panel correctly concluded that it was bound by circuit
precedent in remanding for a new trial. However, our
precedents also demonstrate an enduring disagreement within
our Court over the mandatory-retrial rule.
In Mukhtar v. California State University, Hayward,
299 F.3d 1053, 1068 (9th Cir. 2002), amended by 319 F.3d
1073 (9th Cir. 2003), we held that the non-harmless
6 UNITED STATES V. BACON
admission of testimony without the proper Daubert reliability
determination required vacating for a new trial. Following an
unsuccessful petition for rehearing and rehearing en banc, in
which the petitioners argued that the panel should instead
remand for an evidentiary hearing, the panel amended its
opinion to state:
To remand for an evidentiary hearing
post-jury verdict undermines Daubert’s
requirement that some reliability
determination must be made by the trial court
before the jury is permitted to hear the
evidence. Otherwise, instead of fulfilling its
mandatory role as a gatekeeper, the district
court clouds its duty to ensure that only
reliable evidence is presented with impunity.
A post-verdict analysis does not protect the
purity of the trial, but instead creates an undue
risk of post-hoc rationalization. This is hardly
the gatekeeping role the Court envisioned in
Daubert and its progeny.
Mukhtar v. Cal. State Univ., Hayward, 319 F.3d 1073, 1074
(9th Cir. 2003).
Judge Reinhardt wrote a dissent from the denial of
rehearing en banc in Mukhtar, in which ten additional judges
joined. Id. at 1075–78 (Reinhardt, J., dissenting from denial
of reh’g en banc). The dissent argued, among other things,
that the panel should have conditionally vacated the judgment
pending a limited remand on the admissibility of the expert
testimony. Id. at 1077.
UNITED STATES V. BACON 7
We next considered this issue in Barabin v.
AstenJohnson, Inc. (“Barabin I”), 700 F.3d 428, 433 (9th Cir.
2012). The panel in Barabin I concluded that Mukhtar
required remanding for a new trial when the district court had
committed a non-harmless error in admitting evidence under
Daubert. 700 F.3d at 433. Judge Graber, joined by Judge
Tashima, agreed that circuit precedent required a new trial,
but wrote separately to disagree with Mukhtar and urge that
the judgment be conditionally vacated and remanded to first
determine whether the testimony was admissible. Id. at 434
(Graber, J., concurring) (“If the court finds that the expert
testimony is, indeed, reliable, what purpose is served by
empaneling a new jury and conducting another lengthy trial
the outcome of which likely will be identical to the one
already concluded?”).
We reheard Barabin I en banc, and a six-judge majority
reaffirmed the Mukhtar rule that “an erroneous admission of
expert testimony, absent a showing the error was harmless,
requires a new trial.” Barabin II, 740 F.3d at 467. Judge
Nguyen, joined by four other judges, dissented in part,
writing that “[t]here is no reason to require a new trial
whenever a district court fails to conduct a Daubert analysis,
regardless of whether on remand the district court would
determine that disputed expert testimony is relevant and
reliable.” Id. at 468 (Nguyen, J., concurring in part and
dissenting in part). The partial dissent again urged that the en
banc court conditionally vacate and remand so that the district
court could first determine admissibility. Id. at 471. If the
district court were to determine that the testimony was
admissible, the district court could reinstate the verdict. Id.
If the testimony were held inadmissible, the partial dissent
said, then the district court should ascertain whether the
8 UNITED STATES V. BACON
erroneous admission had prejudiced the defendants. Id. Only
if it had should the court order a new trial. Id.
Shortly afterwards, another panel extended the
mandatory-retrial rule to criminal cases where expert
testimony pertaining to a diminished capacity defense had
been excluded under an incorrect legal standard. Christian,
749 F.3d at 813–14 & n.4. The panel in Christian declined to
determine whether the testimony should have been admitted,
leaving that to the district court to determine in the first
instance. Id. at 813. However, although it was remanding to
allow the district court to determine admissibility, the panel
applied the mandatory-retrial rule, vacating the conviction
and ordering a new trial. Id. at 813–14.
Applying these precedents, the panel in this case properly
concluded that binding circuit precedent required a retrial.
See Ray, 956 F.3d at 1160–61. But, sitting en banc, we are
free to reconsider that rule.
III
As the history of our divided opinions indicates, there is
considerable force behind both the argument that requiring
retrial promotes Daubert’s gatekeeping function, Mukhtar,
319 F.3d at 1074, and the argument that requiring retrial can
waste judicial resources and unnecessarily treats Daubert
errors differently from other evidentiary errors, Barabin II,
740 F.3d at 470–71 (Nguyen, J., concurring in part and
dissenting in part). Moreover, every case presents different
circumstances for the reviewing court to consider. Some
cases involve extensive Daubert hearings; others involve
limited hearings, or no hearings at all. The district court
findings differ, with some courts expressing alternative bases
UNITED STATES V. BACON 9
for the evidentiary decisions. Some cases involve the
erroneous admission of evidence; others involve the
erroneous exclusion of evidence. Mukthar and Barabin, for
example, both concerned a district court’s improper
admission of evidence after failing to make necessary
findings. The Mukhtar panel concluded that a limited remand
for an evidentiary hearing would create an “undue risk of
post-hoc rationalization.” 319 F.3d at 1074. In Christian,
however, we held that the district court improperly excluded
expert testimony by applying the wrong standard, remanded
for the application of the correct standard, but ordered a new
trial regardless of the outcome of the re-examination.
749 F.3d at 813–14.
On the other hand, we have also held that “[i]f the
reviewing court decides the record is sufficient to determine
whether expert testimony is relevant and reliable, it may
make such findings,” and that if such a finding leaves
insufficient evidence, the court “may direct entry of judgment
as a matter of law.” Barabin II, 740 F.3d at 467.
As in Christian, the case before us involves the exclusion
of testimony without an express evaluation of its reliability,
and all three judges on the panel concluded that conditionally
vacating the verdict for an evidentiary hearing would be the
“sensible procedure,” Ray, 956 F.3d at 1161 (Watford, J.,
concurring), in part noting that the government had raised
“very real reliability issues” with the proffered expert
testimony, id. at 1160 (per curiam).
While some logic may support adopting a bright-line rule
either requiring a new trial or requiring a limited remand, we
are mindful that “[t]he life of the law has not been logic; it
has been experience.” Oliver Wendell Holmes, Jr., The
10 UNITED STATES V. BACON
Common Law 1 (1881). Different circumstances may require
different remedies.
Fortunately, we are not presented with an inflexible
binary choice between competing remedies. The United
States Code provides:
The Supreme Court or any other court of
appellate jurisdiction may affirm, modify,
vacate, set aside or reverse any judgment,
decree, or order of a court lawfully brought
before it for review, and may remand the
cause and direct the entry of such appropriate
judgment, decree, or order, or require such
further proceedings to be had as may be just
under the circumstances.
28 U.S.C. § 2106.
Thus, applying section 2106, we hold that when a panel
of this Court concludes that the district court has committed
a non-harmless Daubert error, the panel has discretion to
impose a remedy “as may be just under the circumstances.”
Id. Circumstances may require a new trial in some instances;
circumstances may dictate a limited remand in others. Of
course, the discretion of a panel is not unfettered. The normal
rules of appellate review of evidentiary decisions still apply.
And nothing in our decision removes Daubert’s important
gatekeeping function. But our holding today restores
Daubert errors to the usual realm of appellate review and
remedy, rather than keeping them in a separate, special
category.
UNITED STATES V. BACON 11
To the extent that our prior case law—such as Mukhtar,
Barabin II, and Christian—conflicts with this opinion, we
overrule it. We remand this case to the three-judge panel to
apply its discretion in determining the appropriate remedy.
REMANDED to the three-judge panel.