                FOR PUBLICATION

  UNITED STATES COURT OF APPEALS
       FOR THE NINTH CIRCUIT


UNITED STATES OF AMERICA,                No. 12-10202
                Plaintiff-Appellee,
                                            D.C. No.
                 v.                      2:09-cr-00303-
                                          JCM-VCF-1
ERIC LEON CHRISTIAN,
             Defendant-Appellant.
                                           OPINION


      Appeal from the United States District Court
               for the District of Nevada
       James C. Mahan, District Judge, Presiding

                Argued and Submitted
     September 9, 2013—San Francisco, California

                  Filed April 17, 2014

    Before: Arthur L. Alarcón, Raymond C. Fisher,
        and Marsha S. Berzon, Circuit Judges.

                Opinion by Judge Fisher;
Partial Concurrence and Partial Dissent by Judge Alarcón
2                UNITED STATES V. CHRISTIAN

                           SUMMARY*


                          Criminal Law

     The panel vacated a conviction for two counts of
transmitting through interstate commerce email
communications containing threats to injure the person of
another, in a case in which the defendant argued that the
district court should have allowed his expert, a psychologist
who had earlier examined him for competency to stand trial,
to testify regarding his diminished capacity defense, and that
he was entitled to a jury instruction on diminished capacity
even without such expert testimony.

    The panel held that the district court abused its discretion
by excluding the defendant’s expert solely because he
examined the defendant for competency rather than for
diminished capacity. The panel wrote that instead of focusing
exclusively on the different legal standards governing the
conclusions the expert was asked to draw, the district court
should have evaluated whether the substance of the expert’s
testimony would have helped the jury decide whether the
defendant could form the specific intent to threaten the
recipients of his emails. Although the record did not allow
the panel to determine whether the expert’s testimony should
have been admitted, the panel held that the district court
should not have excluded such testimony without conducting
a voir dire or otherwise giving the expert an opportunity to
explain how he could provide meaningful and relevant


  *
    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. CHRISTIAN                    3

testimony on diminished capacity from the competency
evaluation he had conducted.

    The panel further held that the rule requiring a new trial
when a district court erroneously admits prejudicial expert
testimony in a civil trial, see Estate of Barabin v.
AstenJohnson, Inc., 740 F.3d 457, 2014 WL 129884 (9th Cir.
Jan. 15, 2014) (en banc), also applies to the erroneous
exclusion of expert testimony from a criminal trial. The
panel therefore vacated the defendant’s conviction and
remanded for a new trial.

    The panel held that the district court acted within its
discretion by denying the defendant’s request for a
diminished capacity instruction on this record.

    Judge Alarcón concurred in part and dissented in part. He
concurred in the majority’s conclusion that the panel must
reverse because of the trial judge’s failure to permit defense
counsel to conduct a voir dire examination of the defendant’s
expert, and agreed that Barabin should extend to the
exclusion of expert testimony in criminal cases and compels
a new trial in this case. He dissented from the majority’s
holding that the district court did not abuse its discretion by
denying the defendant’s request for a diminished capacity
jury instruction.
4              UNITED STATES V. CHRISTIAN

                         COUNSEL

Jess R. Marchese (argued), Marchese Law Office, Las Vegas,
Nevada, for Defendant-Appellant.

Peter S. Levitt (argued), Daniel G. Bogden, Robert L. Ellman,
United States Attorney’s Office for the District of Nevada,
Las Vegas, Nevada; Elizabeth Olson White, Roger Yang,
United States Attorney’s Office for the District of Nevada,
Reno, Nevada, for Plaintiff-Appellee.


                         OPINION

FISHER, Circuit Judge:

    Eric Leon Christian appeals his conviction for two
counts of transmitting through interstate commerce email
communications containing threats to injure the person of
another. He argues that the district court should have allowed
his expert, a psychologist who had earlier examined him for
competency to stand trial, to testify regarding his diminished
capacity defense and that he was entitled to a jury instruction
on diminished capacity even without such expert testimony.

    We hold that the district court abused its discretion by
excluding Christian’s expert solely because he examined
Christian for competency rather than for diminished capacity.
Instead of focusing exclusively on the different legal
standards governing the conclusions the expert was asked to
draw, the district court should have evaluated whether the
substance of the expert’s testimony would have helped the
jury decide whether Christian could form the specific intent
to threaten the recipients of his emails. Although the record
               UNITED STATES V. CHRISTIAN                   5

does not allow us to determine whether the expert’s testimony
should have been admitted, the court should not have
excluded such testimony without conducting a voir dire or
otherwise giving the expert an opportunity to explain how he
could provide meaningful and relevant testimony on
diminished capacity from the competency evaluation he had
conducted. We further hold that the rule requiring a new trial
when a district court erroneously admits prejudicial expert
testimony in a civil trial, see Estate of Barabin v.
AstenJohnson, Inc., 740 F.3d 457, 2014 WL 129884 (9th Cir.
Jan. 15, 2014) (en banc), also applies to the erroneous
exclusion of expert testimony from a criminal trial. We
therefore vacate Christian’s conviction and remand for a new
trial.

    Finally, we hold that the district court acted within its
discretion by denying Christian’s request for a diminished
capacity instruction on this record. Accordingly, if no new
evidence supporting a diminished capacity defense is
admitted during Christian’s new trial, the district court need
not give a diminished capacity instruction.

                     BACKGROUND

                             A.

    In May 2009, Christian emailed Joseph Forti, who was
then the Chief of the North Las Vegas Police Department, to
request police assistance retrieving his car, which had been
repossessed several months earlier. Christian argued that the
repossession was not valid and that he was still entitled to
possess the car. When Forti responded that the department
could not help him, Christian emailed a reply that included
several threats of violence, stating: “I will have to kill to
6               UNITED STATES V. CHRISTIAN

retrieve my stolen and items [sic] if you do not retrieve
them”; “I have assembled 100 armed angry men from Nevada
who are ready for civil war if you stop me from protecting my
civil rights”; “Get my fucking car or watch a terrorist car thief
DIE!!!”; and “This communication is protected by the 1st
Amendment and my undying dedication of ridding the earth
of terrorist, [sic] who take away Constitutional Rights like
YOU and the thief who has my car.”

    Christian also emailed threats to Michael Davidson, who
at the time was the chief deputy city attorney and the chief
prosecutor for North Las Vegas. Initially, Christian had
requested copies of the case files for two cases, neither of
which had been prosecuted by Davidson or by the city
attorney’s office. In a follow-up email, Christian demanded
the case files and threatened to “get a mob together and start
a civil war” to kill a state court judge or Davidson himself
unless Davidson “g[o]t the Writ of Habeas Corpus out of the
way.”

    After a two-day trial, a jury convicted Christian of two
counts of transmitting through interstate commerce an email
communication containing a threat to injure the person of
another, in violation of 18 U.S.C. § 875(c).              The
government’s witnesses included Forti and Davidson, who
both testified that they took the threats seriously and took
steps to protect themselves and others they believed might be
in danger of injury. Forti also testified that he believed the
person who sent the email was “very disturbed.”

    Christian rested without testifying or presenting any
evidence on his own behalf. He had sought to raise a
diminished capacity defense, which allows a defendant to
argue that he was incapable of forming the specific intent
                   UNITED STATES V. CHRISTIAN                              7

required by the charged offense – in his case, the specific
intent to threaten. See United States v. Twine, 853 F.2d 676,
678–80 (9th Cir. 1988). The district court precluded
Christian’s proffered expert witness from testifying about
diminished capacity, however, and denied his request for a
diminished capacity jury instruction. Christian’s only
remaining theory of defense was that the government had not
proven that he had the specific intent to threaten when he sent
the emails at issue.

                                     B.

    Before trial, Christian filed notice of his intent to call Dr.
Charles Colosimo, a psychologist, as an expert witness. Dr.
Colosimo had evaluated Christian’s competency to stand trial
during unrelated state court proceedings shortly after
Christian sent the emails at issue. In an interview that lasted
approximately one hour, Dr. Colosimo followed an outline
“designed to assess core procedural competencies” by
probing 13 “areas of functioning” related to an individual’s
ability to assist in his defense.1 Christian was reportedly
hostile and uncooperative throughout the interview. Dr.
Colosimo found Christian’s competence level to be
inadequate in all 13 areas and concluded that Christian could


  1
    Specifically, these areas were: ability to appraise the available legal
defenses; level of unmanageable behavior; quality of relating to his
attorney; ability to plan legal strategy; ability to understand the roles of
various participants in courtroom proceedings; understanding of court
procedure; appreciation of the charges; appreciation of the range and
nature of possible penalties; ability to appraise the likely outcomes;
capacity to disclose to the attorney available pertinent facts surrounding
the offense; capacity to realistically challenge the prosecution witnesses;
capacity to testify relevantly; and manifestation of self-serving rather than
self-defeating motivation.
8              UNITED STATES V. CHRISTIAN

not communicate relevant information to his attorney, make
rational decisions about plea bargaining, consider a mental
illness defense, behave appropriately in the courtroom, make
reasonable defensive decisions or seek the best possible
outcome from his trial.

    Dr. Colosimo also diagnosed Christian with psychosis,
not otherwise specified, probably delusional or paranoid;
personality disorder, not otherwise specified; and probable
learning disabilities, not otherwise specified. He considered
Christian to be at high risk for homicidal behaviors, and
recommended that he be transferred to another facility for
therapeutic care and medication management.

    After the close of the government’s case, defense counsel
informed the district court that he intended to call Dr.
Colosimo to testify regarding Christian’s diminished capacity
defense. Although the court was not inclined to let Dr.
Colosimo testify because he had examined Christian for
competency, not for diminished capacity, it deferred ruling on
the issue until the following morning to allow counsel to
consult Dr. Colosimo and learn “what he has to say, if
anything, about diminished capacity.”

    The next morning, counsel represented that Dr. Colosimo
had said the evaluations for competency and for diminished
capacity were “pretty much one and the same.” The district
court asserted that Dr. Colosimo was incorrect because
different legal standards govern competency, which requires
a defendant to have “sufficient present ability to consult with
his lawyer” and “a factual understanding of the proceedings
before him,” and diminished capacity, which concerns
“whether the defendant has the ability to attain the culpable
state of mind which defines the crime.” For this reason, the
               UNITED STATES V. CHRISTIAN                    9

court did not allow Dr. Colosimo to testify. The court also
ruled that, without Dr. Colosimo’s testimony, there was not
sufficient evidence to support giving a jury instruction on
diminished capacity.

                STANDARD OF REVIEW

    We review for an abuse of discretion the district court’s
exclusion of expert testimony and its refusal to give a jury
instruction based on insufficient evidentiary support. See
United States v. Espinoza-Baza, 647 F.3d 1182, 1191 (9th
Cir. 2011); United States v. W.R. Grace, 504 F.3d 745, 759
(9th Cir. 2007). Under an abuse of discretion standard, we
are required first “to consider whether the district court
identified the correct legal standard for decision of the issue
before it” and then “to determine whether the district court’s
findings of fact, and its application of those findings of fact
to the correct legal standard, were illogical, implausible, or
without support in inferences that may be drawn from facts in
the record.” United States v. Hinkson, 585 F.3d 1247, 1251
(9th Cir. 2009) (en banc).

    The government argues that plain error review applies to
both issues because Christian offered different reasons
supporting the diminished capacity jury instruction at trial
than he does on appeal and because his offer of proof for Dr.
Colosimo’s testimony was inadequate. See United States v.
Bishop, 291 F.3d 1100, 1113 (9th Cir. 2002); United States v.
Varela, 993 F.2d 686, 688 (9th Cir. 1993). We disagree.
Christian argued below, as he does on appeal, that a
diminished capacity jury instruction was supported by the
evidence at trial. Moreover, although counsel’s offer of proof
was inartful, the district court deemed it sufficient to make a
decision and it adequately preserved the evidentiary issue for
10              UNITED STATES V. CHRISTIAN

appeal. See Heyne v. Caruso, 69 F.3d 1475, 1481 (9th Cir.
1995) (“A proper offer of proof informs the trial court of
what counsel expects to prove by the excluded evidence and
preserves the record so that an appellate court can review the
trial court’s decision for reversible error.”). We also note that
the district court several times interrupted defense counsel’s
attempt to make a more complete offer of proof. By the time
counsel was allowed to make any sort of record, the district
court had already precluded Dr. Colosimo’s testimony. See
R.B. Matthews, Inc. v. Transamerica Transp. Servs., Inc., 945
F.2d 269, 272 n.2 (9th Cir. 1991) (“Failure to make an offer
of proof . . . is excused if an offer of proof would have been
redundant, unnecessary, or futile.” (emphasis added)).

                        DISCUSSION

                    A. Expert Testimony

    Christian’s primary argument on appeal is that the district
court abused its discretion by refusing to let him introduce
expert testimony from Dr. Colosimo in support of his
diminished capacity defense. The admissibility of expert
testimony is generally governed by Federal Rule of Evidence
702, which requires district courts to “perform a gatekeeping
function to ensure that the expert’s proffered testimony is
both reliable and relevant.” United States v. Redlightning,
624 F.3d 1090, 1111 (9th Cir. 2010). The district court’s
exclusion of Dr. Colosimo’s testimony implicitly rested on a
relevancy determination: because Dr. Colosimo examined
Christian for competency, not for diminished capacity, the
court concluded that his testimony was not relevant to
Christian’s diminished capacity defense. We hold that the
district court abused its discretion by precluding Dr.
Colosimo’s testimony on this basis because it applied an
               UNITED STATES V. CHRISTIAN                  11

erroneous legal standard. Instead of focusing exclusively on
the different legal standards governing the ultimate
conclusions Dr. Colosimo was asked to draw, the court
should have determined whether testimony regarding his
observations and diagnoses of Christian during the
competency interview would have been relevant and helpful
to the jury in evaluating Christian’s diminished capacity
defense.

    We have explained that a district court deciding whether
to admit expert testimony should evaluate whether that
testimony “will assist the trier of fact in drawing its own
conclusion as to a ‘fact in issue’” and should not limit its
consideration to “the existence or strength of an expert’s
opinion.” United States v. Rahm, 993 F.2d 1405, 1411 (9th
Cir. 1993) (emphasis in original). In Rahm, the defendant
was charged with possession of counterfeit currency and
attempting to pass counterfeit currency; her only defense was
that she did not know the currency was counterfeit. See id. at
1408–09. The district court excluded the testimony of an
expert who had examined Rahm for perceptual difficulties, in
part because the expert did not conclusively opine that Rahm
could not recognize counterfeit currency. See id. at 1410–11.
We reversed, holding that the court should have evaluated
“the test results and the perceptual difficulties they
demonstrate . . . in determining admissibility” instead of
“focus[ing] exclusively upon the proffered expert’s opinion.”
Id. at 1412.

    The district court in this case similarly focused
exclusively on Dr. Colosimo’s expert opinions rather than his
proposed expert testimony. Specifically, the court focused on
the different legal standards governing the ultimate issues on
which Dr. Colosimo had been asked to opine: whether
12             UNITED STATES V. CHRISTIAN

Christian was competent to stand trial and whether Christian
lacked the capacity to form the specific intent to threaten.
Compare Twine, 853 F.2d at 678 (holding that diminished
capacity concerns “whether the defendant possessed the
ability to attain the culpable state of mind which defines the
crime”), with Dusky v. United States, 362 U.S. 402, 402
(1960) (per curiam) (defining the competency standard as
whether the defendant “has sufficient present ability to
consult with his lawyer with a reasonable degree of rational
understanding – and whether he has a rational as well as
factual understanding of the proceedings against him”). The
court thereby overlooked “the psychological test results
underlying the opinion.” Rahm, 993 F.2d at 1412. Just as the
district court in Rahm should have evaluated the “test results
and the perceptual difficulties they demonstrate,” id., the
district court in this case should have considered whether Dr.
Colosimo’s psychological evaluation of Christian would have
been relevant and helpful to the jury in deciding whether
Christian had the capacity to form the specific intent to
threaten when he sent the emails at issue.

    Accordingly, the correct legal standard requires the court
to determine the relevance of the psychological evaluation the
expert conducted and the medical diagnoses he made, not his
ultimate legal conclusion regarding the defendant’s mental
state. The district court overlooked this distinction when it
asserted that Dr. Colosimo was wrong to say he would have
used the same methods to evaluate Christian for diminished
capacity as he had for competency. Dr. Colosimo had not
opined that the legal standards for diminished capacity and
competency were the same, but that, as a doctor, he would
have conducted the same evaluation and gathered the same
psychological information. That Dr. Colosimo initially used
the results of the evaluation to formulate an opinion about
                  UNITED STATES V. CHRISTIAN                            13

competency does not mean he could not have used the same
results to formulate an opinion about diminished capacity.

    In fact, Dr. Colosimo could not have explicitly testified
that Christian lacked the capacity to form the specific intent
to threaten. See Fed. R. Evid. 704(b) (“In a criminal case, an
expert witness must not state an opinion about whether the
defendant did or did not have a mental state or condition that
constitutes an element of the crime charged or of a defense.”);
United States v. Morales, 108 F.3d 1031, 1037 (9th Cir.
1997) (en banc) (holding that Rule 704(b) prohibits an expert
witness in a criminal case from “stat[ing] an opinion or
draw[ing] an inference which would necessarily compel the
conclusion” that the defendant lacked the requisite mental
state).2 In Rahm, we pointed out that “[i]t would make little


 2
   We acknowledge that Rule 704(b) would have limited the scope of Dr.
Colosimo’s testimony, but we reject the government’s argument that the
rule would have prohibited him from testifying at all. The government’s
argument rests entirely on the description of Dr. Colosimo’s proposed
testimony in Christian’s brief as being that Christian “did not have the
ability or capacity to understand that his subject emails would be
perceived as a real or actual threat of bodily harm.” Although the
government is correct that Rule 704(b) would have prohibited Dr.
Colosimo from offering that precise opinion, the rule “allows expert
testimony on a defendant’s mental state so long as the expert does not
draw the ultimate inference or conclusion for the jury.” United States v.
Finley, 301 F.3d 1000, 1015 (9th Cir. 2002); see also Morales, 108 F.3d
at 1033 (holding that an expert may “give an opinion on a predicate matter
from which a jury might infer the defendant’s required mens rea”).
Testimony regarding Dr. Colosimo’s diagnoses and the results of the
psychological evaluation Dr. Colosimo gave Christian should not run
afoul of this restriction. See Finley, 301 F.3d at 1015 (holding that expert
testimony regarding the defendant’s “atypical belief system” did not
violate Rule 704(b)’s prohibition because “[t]he jury was free to conclude
that [the defendant] knew the notes were fraudulent, despite the rigidity
of his belief system”).
14             UNITED STATES V. CHRISTIAN

sense to require a conclusive opinion in determining
admissibility, and then absolutely to forbid expression of the
opinion in testimony.” 993 F.2d at 1411 n.3. So too here.
Because Dr. Colosimo could not have properly testified that
Christian lacked the capacity to form the requisite specific
intent to threaten, the absence of an opinion to that effect in
his report is not a valid reason to preclude his testimony.
Particularly under these circumstances, focusing on the
expert’s evaluation rather than his ultimate conclusion makes
perfect sense.

    Dr. Colosimo’s report reveals that portions of his
competency evaluation were probably relevant to Christian’s
diminished capacity defense. For example, Dr. Colosimo
diagnosed Christian with psychosis, including probable
delusions, and borderline personality disorder. Testimony
regarding the behavior Christian exhibited that led Dr.
Colosimo to make these diagnoses and the likely effects of
these conditions may well have been helpful to the jury in
deciding whether Christian could form the requisite intent to
threaten. Additionally, a few of the “areas of functioning”
that Dr. Colosimo probed during the competency evaluation
relate to a diminished capacity determination. In particular,
Christian’s ability to appraise the likely outcomes of his
actions would bear on his ability to understand whether the
recipients of his emails would perceive them as threats.

    We do not hold that Dr. Colosimo’s testimony must be
admitted, however, only that there were sufficient indicia of
relevance in defense counsel’s proffer and in Dr. Colosimo’s
expert report to warrant giving Dr. Colosimo an opportunity
to explain how the psychological information he gathered
during Christian’s competency evaluation was relevant to a
diminished capacity defense. Defense counsel requested an
               UNITED STATES V. CHRISTIAN                    15

opportunity “to lay the proper foundation” by putting Dr.
Colosimo on the stand and asking how the competency
evaluation he conducted would bear on the issue of
diminished capacity. The district court should have explored
the relevance of Dr. Colosimo’s testimony by allowing
defense counsel an opportunity to conduct a voir dire of Dr.
Colosimo. See United States v. Adams, 271 F.3d 1236, 1241
(10th Cir. 2001) (explaining that the most desirable method
for an offer of proof is conducting a voir dire of the expert
and the least desirable is asking counsel what the proffered
testimony would be).

    Finally, the district court’s error was not harmless because
it “prevent[ed] the defendant from providing an evidentiary
basis for his defense.” United States v. Saenz, 179 F.3d 686,
689 (9th Cir. 1999). Christian’s only defense to the charged
offenses was that he did not have the requisite intent to
threaten. Expert testimony supporting the inference that he
was not capable of forming such intent would have bolstered
his argument and entitled him to a diminished capacity jury
instruction. As we explain in Part B, infra, Christian’s erratic
behavior already supports the inference that he suffered some
sort of mental illness; evidence of a link between that illness
and his capacity to form a specific intent to threaten, even
slight, would have provided an evidentiary basis for his
requested jury instruction. Although the record does not
reveal the precise content of Dr. Colosimo’s testimony, it
does indicate that, if his testimony had been admitted, he
likely would have provided some evidentiary basis for
inferring such a link between Christian’s obvious mental
illness and Christian’s sole defense.              Under these
circumstances, we have no difficulty concluding that
Christian’s substantial rights were affected by the district
court’s error. See Fed. R. Evid. 103(a).
16                 UNITED STATES V. CHRISTIAN

    Having concluded that the district court abused its
discretion and that its error was not harmless, we must
determine the appropriate remedy. We recently held in
Barabin v. AstenJohnson, Inc., 740 F.3d 457, 2014 WL
129884 (9th Cir. Jan. 15, 2014) (en banc), that when “the
erroneous admission of evidence actually prejudiced the
defendant, such that the error was not harmless, the
appropriate remedy is a new trial.” Id. at *1, *7. Under
Barabin, a new trial is warranted when evidence admitted
through an erroneous analysis prejudices the opposing party
but the record is too sparse to conduct a proper admissibility
analysis and decide whether the admission itself was
erroneous. See id. at *7; id. at *9–10 (Nguyen, J., concurring
in part and dissenting in part).3



  3
    We emphasize that neither Barabin nor this decision requires a new
trial whenever a district court errs in analyzing the admissibility of expert
testimony. Barabin affirmed Mukhtar v. California State University, 299
F.3d 1053 (9th Cir. 2002), amended by 319 F.3d 1073 (9th Cir. 2003),
only to the extent it held “that an erroneous admission of expert testimony,
absent a showing the error was harmless, requires a new trial.” Barabin,
2014 WL 129884, at *7; see also id. (assuming that “a limited remand is
available post-Mukhtar,” but declining to remand where “the evidence
was prejudicial” (emphasis added)); id. at *7 (Nguyen, concurring in part
and dissenting in part) (noting that the Barabin majority “open[ed] the
door to a limited remand . . . by overruling Mukhtar”). In this case, as in
Barabin, the record amply demonstrates that the district court’s error was
prejudicial even though the record is not sufficient to determine whether
the evidence at issue was admissible. See supra at 15–16; Barabin, 2014
WL 129884, at *5. Under different circumstances, however, a limited
remand remains available. For example, if the record did not permit us to
ascertain that “severe prejudice” resulted from the district court’s
evidentiary determination, id. at *8, perhaps because the district court
excluded such evidence without obtaining an adequate proffer or
conducting an adequate voir dire, a limited remand on the question of
prejudice, rather than admissibility, would be appropriate.
                  UNITED STATES V. CHRISTIAN                            17

    Although Barabin involved the admission of expert
testimony in a civil trial and this case involves the exclusion
of expert testimony from a criminal trial, we hold that
Barabin’s analysis applies with equal force to these
circumstances. Barabin extended a general evidentiary rule
requiring a new trial “[w]hen the district court has
erroneously admitted or excluded prejudicial evidence” to the
admission of expert testimony. Id. at *6. Nothing in the
analysis suggests that the general rule, which encompasses
the exclusion of non-expert evidence, should not also extend
to the exclusion of expert testimony. We also see no reason
that the rule announced in Barabin should not apply to
criminal cases. The same rules of evidence, including Rule
702, govern both civil and criminal proceedings. See Fed. R.
Evid. 1101(b); United States v. Webb, 115 F.3d 711, 716 (9th
Cir. 1997) (Jenkins, J., concurring in the result), abrogated on
other grounds by Kumho Tire Co. v. Carmichael, 526 U.S.
137 (1999). It follows that the remedies for violations of
those evidentiary rules generally should also be consistent
across civil and criminal cases.4

    Accordingly, because the district court erred when it
excluded Dr. Colosimo’s expert testimony and that exclusion
prejudiced the defendant, but “the record before us is too


  4
    We recognize that Barabin distinguished two criminal cases, United
States v. Cordoba, 104 F.3d 225 (9th Cir. 1997), and United States v.
Amador-Galvan, 9 F.3d 1414 (9th Cir. 1993), in which the court vacated
the conviction and remanded for an evidentiary hearing, but allowed the
district court to reinstate the conviction if it reached the same conclusion
under the proper standard. See Barabin, 2014 WL 129884, at *7;
Cordoba, 104 F.3d at 229; Amador-Galvan, 9 F.3d at 1418. The material
distinction was not that they were criminal cases, however, but that they
were initial attempts to “grappl[e] with the effects of Daubert” that were
impliedly overruled “[a]fter the dust of Daubert had settled.” Id. at *7.
18              UNITED STATES V. CHRISTIAN

sparse to determine whether the expert testimony is relevant
and reliable,” we vacate Christian’s conviction and remand
for a new trial. Barabin, 2014 WL 129884, at *7.

                     B. Jury Instruction

     Christian also argues that, even without Dr. Colosimo’s
testimony, the district court abused its discretion by refusing
to give a jury instruction on his diminished capacity defense.
It is “well established that a criminal defendant is entitled to
have a jury instruction on any defense which provides a legal
defense to the charge against him and which has some
foundation in the evidence, even though the evidence may be
weak, insufficient, inconsistent, or of doubtful credibility.”
United States v. Yarbrough, 852 F.2d 1522, 1541 (9th Cir.
1988). The defendant need not introduce his own evidence to
be entitled to a jury instruction on his theory of defense if
there is “some foundation” for the defense in the
government’s evidence. See United States v. Bello-Bahena,
411 F.3d 1083, 1090–91 (9th Cir. 2005). When there is some
foundation in the evidence for the defendant’s theory of
defense, the denial of an instruction regarding that defense
warrants per se reversal. See id. at 1091 n.6.

     We hold that the district court did not abuse its discretion
by denying Christian’s request for a diminished capacity jury
instruction on this record, because there was not a sufficient
foundation for the instruction in the evidence presented at
trial. Christian argues that the inherent irrationality of the
threats themselves, which he characterizes as “the utterances
of an irrational, even lunatic, mind,” is sufficient to warrant
a diminished capacity instruction. Additionally, as the
dissent points out, former Chief of Police Forti testified that
                UNITED STATES V. CHRISTIAN                     19

he believed the person who sent such threats was very upset
and “very disturbed.” Dissent at 21.

    Although a jury could reasonably infer from this evidence
that Christian suffered from some form of mental illness, his
argument fails because such evidence, standing alone, is not
sufficient to require a diminished capacity instruction. The
diminished capacity defense is not cognizable simply because
a criminal defendant may be mentally ill; instead, the defense
“is directly concerned with whether the defendant possessed
the ability to attain the culpable state of mind which defines
the crime.” Twine, 853 F.2d at 678. A jury instruction was
required only if there was some evidence supporting a link
between Christian’s mental illness and his ability to form a
specific intent to threaten, though that evidence may be
“weak, insufficient, inconsistent, or of doubtful credibility.”
See United States v. Washington, 819 F.2d 221, 225 (9th Cir.
1987). Christian sought to present evidence of that link
through Dr. Colosimo’s testimony, which the district court
erroneously excluded as discussed in Part A, supra. Absent
that crucial evidence, we respectfully disagree with the
dissent that the jury was entitled to infer that Christian could
not form the requisite intent to threaten.

    If any evidence, expert or otherwise, supporting a link
between Christian’s mental illness and his ability to form the
intent to threaten is presented during the new trial, the district
court must give the jury a diminished capacity instruction.
Because no such evidence was introduced at the original trial,
it was within the district court’s discretion to deny Christian’s
request for a diminished capacity jury instruction on that
record. Assuming, however, that the district court (after voir
dire under the proper legal standard) admits Dr. Colosimo’s
20              UNITED STATES V. CHRISTIAN

testimony, there would likely be sufficient evidence to
support such an instruction.

                       CONCLUSION

     We hold that the district court abused its discretion by
focusing exclusively on the different legal standards for
competency and diminished capacity without considering
whether Dr. Colosimo’s testimony would have helped the
jury assess Christian’s diminished capacity defense. We
therefore vacate Christian’s conviction and remand for a new
trial.

     VACATED and REMANDED.




ALARCÓN, Circuit Judge, concurring in part and dissenting
in part:

    I concur in the majority’s conclusion in Part A that we
must reverse because of the trial judge’s failure to permit
defense counsel to conduct a voir dire examination of Dr.
Colosimo. His expert testimony may be sufficient to support
a jury’s finding that Christian lacks the capacity to form a
specific intent to threaten another. I also agree that Barabin
v. AstenJohnson, Inc., — F.3d —, 2014 WL 129884 (9th Cir.
Jan. 15, 2014) (en banc), should extend to the exclusion of
expert testimony in criminal cases and compels a new trial in
this case. I respectfully dissent from the majority’s holding
in Part B that the district court did not abuse its discretion by
                UNITED STATES V. CHRISTIAN                    21

denying Christian’s request for a diminished capacity jury
instruction on the record before it.

     I agree with the majority that a criminal defendant is
entitled to have a jury instruction on any theory that provides
a legal defense to the charge against him if there is some
support in the record for that defense, and that this is so even
when the evidentiary foundation for the defendant’s defense
rests solely in the government’s evidence. Maj. Op. at 18
(citing United States v. Yarbrough, 852 F.2d 1522, 1541 (9th
Cir. 1988); United States v. Bello-Bahena, 411 F.3d 1083,
1090–91 (9th Cir. 2005)). I further recognize that this Court
has held that “a mere scintilla of evidence supporting the
defendant’s theory is not sufficient to warrant a defense
instruction.” United States v. Johnson, 459 F.3d 990, 993
(9th Cir. 2006) (emphasis added) (internal quotation marks
omitted). As the majority opinion notes, however, we have
also previously held that “a criminal defendant is entitled to
have a jury instruction on any defense which provides a legal
defense to the charge against him and which has some
foundation in the evidence, even though the evidence may be
weak, insufficient, inconsistent, or of doubtful credibility.”
Maj. Op. at 18 (emphasis added) (quoting Yarbrough, 852
F.2d at 1541).

    In an email to Joseph Forti, the Chief of Police of the
North Las Vegas Police Department, Christian asserted that
he had “assembled 100 armed angry men from Nevada who
are ready for civil war if you stop me from protecting my
civil rights”; “Get my fucking car or watch a terrorist car thief
DIE!!!” Chief Forti testified that Christian was “very
disturbed.” The majority concedes that “Christian’s erratic
behavior . . . supports the inference that he suffered some sort
of mental illness.” Maj. Op. at 15. The jury should have
22             UNITED STATES V. CHRISTIAN

been permitted to determine whether they could infer from
this evidence of Christian’s mental condition whether his
capacity to threaten others was diminished.

    “A criminal defendant has a constitutional right to have
the jury instructed according to his theory of the case . . . .”
United States v. Marguet–Pillado, 648 F.3d 1001, 1006 (9th
Cir. 2011) (internal quotation marks omitted). We held in
United States v. Yarbrough, 852 F.2d 1522 (9th Cir. 1988),
that “a criminal defendant is entitled to have a jury instructed
on any defense which provides a legal defense to the charge
against him and which has some foundation in the evidence,
even though the evidence may be weak, insufficient,
inconsistent, or of doubtful credibility.” Id. at 1541.

    While conceding that the evidence is sufficient to show
that Christian suffers from some sort of mental illness, the
majority has inferred that this evidence is insufficient to
demonstrate diminished capacity. The failure to instruct the
jury on the defense of diminished capacity prevented the jury
from determining whether the circumstantial evidence of
Christian’s mental illness was sufficient or insufficient to
persuade it that Christian lacked the capacity to form the
intent to threaten others.

    A district court’s “failure to instruct the jury on the
defendant’s theory of the case, where there is evidence to
support such instruction, is reversible per se and can never be
considered harmless error.” United States v. Zuniga, 6 F.3d
569, 571 (9th Cir. 1993). On this record, I would hold that
the district court’s refusal to instruct the jury on Christian’s
theory of the case is reversible per se.
