                                  IN THE

 SUPREME COURT OF THE STATE OF ARIZONA
                               __________

                           STATE OF ARIZONA,
                               Appellee,

                                       v.

                        STEPHEN JAY MALONE JR.,
                               Appellant.

                               ____________________


                           No. CR-18-0431-PR
                           Filed July 17, 2019
                                __________________


            Appeal from the Superior Court in Pima County
              The Honorable Richard D. Nichols, Judge
                        No. CR20132518-001
                             AFFIRMED

             Opinion of the Court of Appeals, Division Two
                       245 Ariz. 103 (App. 2018)
                              VACATED
                             ____________

COUNSEL:

Mark Brnovich, Arizona Attorney General, O.H. Skinner, Solicitor General,
Joseph T. Maziarz, Chief Counsel, Criminal Appeals Section, Michael T.
O’Toole (argued), Assistant Attorney General, Phoenix, Attorneys for State
of Arizona

James L. Fullin, Pima County Legal Defender, Jeffrey Kautenburger
(argued), Assistant Legal Defender, Pima County Legal Defender’s Office,
Tucson, Attorneys for Stephen Jay Malone Jr.

David J. Euchner, Tucson, Attorney for Amicus Curiae Arizona Attorneys
for Criminal Justice
                            STATE v. MALONE
                            Opinion of the Court


                           ____________________

JUSTICE TIMMER authored the opinion of the Court, in which VICE
CHIEF JUSTICE BRUTINEL and JUSTICES BOLICK, GOULD, LOPEZ, and
PELANDER (RETIRED) joined. CHIEF JUSTICE BALES dissented in part
and concurred in the judgment.

JUSTICE TIMMER, opinion of the Court:

¶1            Although a defendant cannot use evidence of a mental
disease or defect to show he did not form a crime’s requisite mental state
(mens rea), see State v. Mott, 187 Ariz. 536, 541 (1997); State v. Schantz, 98
Ariz. 200, 212–13 (1965), he may use evidence of a character trait for
impulsivity to cast doubt on the existence of premeditation, see State v.
Christensen, 129 Ariz. 32, 35 (1981), which forms part of the mens rea for first
degree murder under A.R.S. § 13-1105(A)(1), see State v. Boyston, 231 Ariz.
539, 549 ¶ 50 (2013). Here, we decide whether a defendant who introduces
expert evidence of a character trait for impulsivity to challenge
premeditation may also introduce evidence of brain damage to corroborate
the existence of that trait. We hold he cannot.

                              BACKGROUND

¶2             Stephen Jay Malone Jr. and A.S. lived together in a
tumultuous romantic relationship. On June 9, 2013, A.S. left Malone,
moving from their home with their three children. Two evenings later, A.S.,
along with her sister, E.S., and two of the children, drove to the home to
return a gift to Malone. On the way, A.S. spoke to Malone by phone and
told him that despite his threats, she was leaving him. When A.S. arrived,
Malone came up to the car, took the returned gift, and asked her to stay so
his mother, who was in the house, could see the children. A.S. refused and
drove away; Malone quickly followed in another car. After a five-to-six-
minute chase, during which Malone blocked A.S.’s car twice, Malone
jumped from his car and fired multiple gunshots into A.S.’s car, killing A.S.
and injuring E.S.

¶3            The State indicted Malone on several charges, including
premeditated first degree murder, see § 13-1105(A)(1), the only charge at
issue here. Before trial, the State moved to preclude expert testimony from
psychologist James Sullivan, Ph.D, that Malone’s performance on
neuropsychological assessment tests was “consistent with significant and


                                       2
                            STATE v. MALONE
                            Opinion of the Court

permanent diffuse brain damage,” meaning Malone was “more likely to
have a character trait for impulsivity.” (Dr. Sullivan did not obtain an MRI
scan or like evidence to bolster his assessment that Malone had brain
damage.) While acknowledging that Christensen permitted Dr. Sullivan to
testify that Malone had a character trait for impulsivity, the State argued
that Mott precluded evidence that brain damage made the existence of this
trait more likely. Over defense objection, the trial court granted the motion
and precluded Dr. Sullivan from offering an opinion at trial regarding brain
damage.

¶4            At trial, Malone rebutted the State’s allegation that he
premeditated A.S.’s murder by introducing evidence suggesting he had
acted impulsively. To that end, Dr. Sullivan testified that, based on his
observations and psychological tests, Malone had a character trait for
impulsivity. Dr. Sullivan explained that people with this character trait are
compromised in their ability to think through the consequences of their
actions before acting, although they are capable of doing so. The State did
not contest that Malone had a character trait for impulsivity but
nevertheless maintained he premeditated A.S.’s murder. The jury agreed
and found Malone guilty as charged.

¶5            In a split decision, the court of appeals concluded the trial
court erred by precluding Dr. Sullivan’s testimony concerning brain
damage. State v. Malone, 245 Ariz. 103, 107 ¶ 16 (App. 2018). The court
nevertheless found the error harmless and therefore affirmed. Id. at 108–09
¶ 22.

¶6            We granted Malone’s petition for review (challenging
harmless error) and the State’s cross-petition for review (challenging error)
because they involve a recurring issue of statewide importance. We have
jurisdiction pursuant to article 6, section 5 of the Arizona Constitution.

                               DISCUSSION

                                      I.

¶7             We review the trial court’s preclusion of Dr. Sullivan’s brain-
damage testimony for an abuse of discretion. See State v. Leteve, 237 Ariz.
516, 524 ¶ 18 (2015). “An error of law committed in reaching a discretionary
conclusion may, however, constitute an abuse of discretion.” State v. Wall,
212 Ariz. 1, 3 ¶ 12 (2006).



                                      3
                            STATE v. MALONE
                            Opinion of the Court

                                      II.

¶8             Before addressing the admissibility of Dr. Sullivan’s brain-
damage testimony, we set forth general legal principles underlying the
issue. First, apart from insanity, Arizona does not permit a defendant to
introduce evidence of a mental disease or defect as either an affirmative
defense or to negate the mens rea element of a crime. See Mott, 187 Ariz.
at 540–41; Schantz, 98 Ariz. at 212; see also A.R.S. § 13-502(A) (“A person may
be found guilty except insane if at the time of the commission of the criminal
act the person was afflicted with a mental disease or defect of such severity
that the person did not know the criminal act was wrong.”). Thus, for
example, in Mott this Court held that the trial court properly excluded
evidence that the defendant suffered from battered-woman syndrome
because it was offered to negate the mens rea element for child abuse
(knowledge or intent). 187 Ariz. at 539, 544–45. And in Schantz we held
that the trial court properly refused a jury instruction that would have
permitted the jury to consider expert evidence that the defendant killed his
wife “without his deliberate volitional conscious awareness” to contest the
mens rea element for second degree murder (malice aforethought). 98 Ariz.
at 204–06, 213.

¶9             Using mental disease or defect evidence to refute the mens rea
element of a crime is commonly referred to as a “diminished capacity” or
“diminished responsibility” defense. Mott, 187 Ariz. at 540; see Leteve, 237
Ariz. at 524 ¶ 20. Such evidence does not provide a complete defense to a
crime or excuse it but “establish[es], by negating the requisite intent for a
higher degree of the offense, that in fact a lesser degree of the offense was
committed.” McCarthy v. State, 372 A.2d 180, 182 (Del. 1977) (quoting C.T.
Drechsler, Annotation, Mental or Emotional Condition as Diminishing
Responsibility for Crime, 22 A.L.R. 3d 1228, 1238 (1968)). As mentioned,
Arizona does not permit this defense. See Mott, 187 Ariz. at 540–41; Schantz,
98 Ariz. at 212.

¶10          Second, evidence of a defendant’s behavioral tendencies is
not diminished capacity evidence and may be admitted to challenge the
mens rea of premeditation for a first degree murder charge. See Christensen,
129 Ariz. at 35–36. The defendant in Christensen was charged with
premeditated first degree murder and sought to elicit a psychiatrist’s
testimony that, based on interviews and diagnostic testing results, the
defendant “had difficulty dealing with stress and in stressful situations his
actions were more reflexive than reflective.” Id. at 34. The trial court
precluded the testimony as diminished capacity evidence. Id. This Court


                                      4
                            STATE v. MALONE
                            Opinion of the Court

reversed, reasoning that the testimony evinced a character trait that
“tend[ed] to establish that [the defendant] acted impulsively” and would
have assisted jurors in determining whether the defendant acted with
premeditation. Id. at 35; see also Ariz. R. Evid. 404(a)(1) (authorizing
admission of character trait evidence offered by an accused); Ariz. R. Evid.
405(a) (stating that character trait evidence can be offered as an opinion).
The Court cautioned, however, that an expert witness could not opine as to
whether a defendant was acting reflectively or reflexively at the time of the
murder. Christensen, 129 Ariz. at 35–36.

¶11            The United States Supreme Court in Clark v. Arizona, 548 U.S.
735, 757 (2006), coined the term “observation evidence” to describe the type
of character trait evidence permitted in Christensen. See also State v. Richter,
245 Ariz. 1, 8 ¶ 33 (2018); Leteve, 237 Ariz. at 401 ¶ 21. “Observation
evidence” is a slight misnomer, however, as the psychiatrist’s opinion in
Christensen, like Dr. Sullivan’s proffered brain-damage testimony here,
depended on results from diagnostic tests administered to the defendant as
well as the psychiatrist’s personal observations of him. See Christensen, 129
Ariz. at 34. A more accurate term for the evidence deemed admissible in
Christensen is “behavioral-tendency evidence,” which is admissible to show
a character trait. See Mott, 187 Ariz. at 544 (describing Christensen as
involving “evidence about [the defendant’s] behavioral tendencies”); see
also Ariz. R. Evid. 404(a)(1) (permitting evidence of an accused’s pertinent
character trait).

                                      III.

                                      A.

¶12            Turning to this case, the dispute is whether Dr. Sullivan’s
proffered brain-damage testimony was inadmissible diminished capacity
evidence under Schantz and Mott, as the trial court ruled, or admissible
behavioral-tendency evidence under Christensen, as the court of appeals
concluded. We quickly reject Malone’s assertion that Mott could not apply
here because it only considered psychological conditions, not brain
damage, as mental diseases or defects underlying prohibited diminished
capacity defenses.       Nothing in Mott draws this fine distinction.
Significantly, in overruling State v. Gonzales, 140 Ariz. 349 (1984), which had
approved use of expert testimony that a defendant’s “low intelligence and
probable organic brain damage affected his ability to reason” and made him
unable to form the mens rea for rape, Mott necessarily considered brain
damage as a mental defect by characterizing the expert’s testimony in


                                       5
                            STATE v. MALONE
                            Opinion of the Court

Gonzales as diminished capacity evidence. Mott, 187 Ariz. at 544.
Dr. Sullivan’s precluded brain-damage testimony constitutes the type of
mental-defect evidence addressed by Mott.

¶13           Malone next argues that mental disease or defect evidence is
only inadmissible under Mott if that disease or defect rendered the
defendant entirely incapable of forming the requisite mens rea. Thus,
because Dr. Sullivan’s proffered brain-damage testimony purportedly
would have shown only that Malone was impulsive and therefore less
likely to premeditate but not incapable of doing so, Mott is inapplicable.
The State counters that Mott precluded all mental disease or defect evidence
unless used to show legal insanity under § 13-502, meaning the brain-
damage evidence here was properly precluded.

¶14           We do not view Mott as precluding only mental disease or
defect evidence that renders a defendant incapable of forming mens rea.
Malone relies on language in Mott that, in isolation, supports his
interpretation. See Mott, 187 Ariz. at 544 (distinguishing Christensen by
noting that the evidence there “was not that [Christensen] was incapable, by
reason of a mental defect, of premeditating or deliberating but that, because
he had a tendency to act impulsively, he did not premeditate the homicide.
Because he was not offering evidence of his diminished capacity, but only
of a character trait relating to his lack of premeditation, the defendant was
not precluded from presenting the expert testimony.”). But the disputed
evidence in Mott was expert testimony that the “defendant was not capable
of forming the requisite mental state of knowledge or intent,” so it is not
surprising the Court focused on incapability when distinguishing
Christensen. See id. at 540.

¶15            Elsewhere in Mott, the Court indicated that prohibited mental
disease or defect evidence included anything affecting a defendant’s
actions, excepting evidence of legal insanity. See id. at 540, 544 (describing
prohibited diminished capacity evidence as “negat[ing] the mens rea” and
concluding that evidence “affect[ing] the defendant’s capacity” to decide
whether to get medical help for her child is inadmissible as diminished
capacity evidence (emphasis removed)). And significantly, Mott overruled
Gonzales, which had concluded that evidence of impaired cognitive
functioning that affected the defendant’s judgment was relevant to whether
he acted with the requisite mens rea and therefore admissible. See Mott, 187
Ariz. at 544; Gonzales, 140 Ariz. at 350, 352–53.




                                      6
                             STATE v. MALONE
                             Opinion of the Court

¶16              This Court’s pre-Mott decisions are in accord with our view.
See, e.g., State v. Ramos, 133 Ariz. 4, 6 (1982) (“Psychiatric testimony to negate
specific intent has consistently been excluded.”); State v. Briggs, 112 Ariz.
379, 382 (1975) (“Arizona does not permit psychiatric evidence of a mental
disease or defect negativing a state of mind.”); State v. Malumphy, 105 Ariz.
200, 202 (1969) (concluding that the trial court properly “refus[ed] to
instruct the jury that it could consider evidence of defendant’s mental
condition in determining whether defendant, in fact, entertained
premeditation and deliberation” as that instruction “embodies the precept
commonly referred to as the doctrine of ‘diminished responsibility,’” which
Arizona rejects); Schantz, 98 Ariz. at 207–08 (describing diminished
responsibility evidence as permitting a jury to “consider defects in the
volitional processes to determine the lack of deliberation and
premeditation” or “the lack of malice aforethought”).

¶17            Mott’s focus on the adoption of our criminal code further
illuminates the Court’s view that prohibited diminished capacity evidence
includes a mental disease or defect that reduces the likelihood that a
defendant formed the requisite mens rea. The Court noted that the
legislature “declined to adopt the defense of diminished capacity” set forth
in the 1962 version of the Model Penal Code (“MPC”) § 4.02(1): “Evidence
that the defendant suffered from a mental disease or defect is admissible
whenever it is relevant to prove that the defendant did or did not have a
state of mind that is an element of the offense.” 187 Ariz. at 540; see also
Schantz, 98 Ariz. at 212–13 (declining to adopt then-draft MPC § 4.02(1)
“piecemeal” and deferring to the legislature whether to adopt or reject it as
part of article 4 of the draft MPC). According to the Court, “[t]his section
was written in recognition of the existence of degrees of mental disease or
defect that fall short of that required for invoking the defense of
irresponsibility [legal insanity], but that may be put in evidence as tending
to show that the defendant lacked the specific mens rea required for the
commission of the offense charged.” Mott, 187 Ariz. at 540 (internal
quotation marks omitted) (quoting MPC and Commentaries § 4.02(1) cmt.
2 (1985)). By omitting § 4.02(1) from our code, the Court reasoned, the
legislature rejected “use of psychological testimony to challenge the mens
rea element of a crime.” Id. In other words, mental disease or defect
evidence falling short of demonstrating legal insanity cannot be admitted
to challenge the mens rea element of a charged offense. See Clark, 548 U.S.
at 762 (“[W]e understand that Mott is meant to confine to the insanity
defense any consideration of characteristic behavior associated with mental
disease.”); Leteve, 237 Ariz. at 524 ¶ 20 (reaffirming that diminished capacity
evidence cannot be used to negate mens rea and describing such evidence

                                        7
                            STATE v. MALONE
                            Opinion of the Court

as a “mental disorder short of insanity” (citing Mott, 187 Ariz. at 541)); State
v. Jacobson, 244 Ariz. 187, 193 ¶ 21 (App. 2017) (stating expert evidence that
hormonal changes “could affect planning, thinking, mental state, judgment,
insight, perception and memory” was diminished capacity evidence
prohibited by Mott).

¶18           The court of appeals acknowledged that Dr. Sullivan’s
proffered brain-damage testimony was diminished capacity evidence. See
Malone, 245 Ariz. at 106 ¶¶ 7, 9. But the court viewed Mott’s differentiation
of Christensen as authorizing admission of mental disease or defect evidence
for the purpose of showing a behavioral tendency that negates mens rea.
Id. at 106–07 ¶¶ 10–12. Because Dr. Sullivan’s test results “were offered to
demonstrate a brain condition that rendered it less likely” that Malone
premeditated the murder, the evidence was deemed admissible “to
corroborate the defendant’s claims that he had a character trait of
impulsivity.” Id. ¶ 11. The court noted that the trial court could have
facilitated proper use of the evidence with a limiting instruction or other
measures. See id. at 107 ¶ 15.

¶19            We reject the court of appeals’ purpose-oriented standard for
admitting mental disease or defect evidence to negate mens rea. As
previously discussed, see supra ¶ 17, Arizona has not adopted MPC
§ 4.02(1), which would have permitted Dr. Sullivan’s brain-damage
testimony as relevant to the existence of mens rea. Consequently, mental
disease or defect evidence, whether introduced to show a defendant’s
inability to form mens rea or a likelihood he failed to do so, cannot be used
to negate mens rea.

¶20           We are not persuaded to reach a different result because the
proffered brain-damage testimony corroborates the existence of a
behavioral tendency. We agree with the court of appeals’ dissent that,
regardless of the corroborating character of this evidence, it was
inescapably offered to refute premeditation and is therefore inadmissible
under Schantz and Mott. Malone, 245 Ariz. at 111 ¶ 38 (Brearcliffe, J.,
concurring in part and dissenting in part). To conclude otherwise would
circumvent Arizona’s longstanding jurisprudence, including those cases,
by permitting defendants to introduce evidence of a behavioral tendency
and then “corroborating” its existence by providing mental disease or
defect evidence to explain the cause for that behavior. For example, under
this standard, the expert in Mott could have first testified that the defendant
had a character trait of not sensing danger (part of the excluded evidence)
and then corroborated it with evidence of battered woman syndrome. See


                                       8
                             STATE v. MALONE
                             Opinion of the Court

Mott, 187 Ariz. at 539–40. Although behavioral-tendency evidence is
permissible to negate mens rea, linking that behavior to a mental disease or
defect, whether directly or under the guise of corroboration, is
impermissible. Cf. Richter, 245 Ariz. at 9 ¶ 36 (stating that an expert’s
opinion cannot be used “to serve as a mere conduit for otherwise
inadmissible testimony”). (The prosecution here did not contest that
Malone has a character trait for impulsivity. Thus, the parties have not
addressed whether the defense can introduce mental disease or defect
evidence to corroborate behavioral-tendency evidence when the
prosecution challenges the latter. We leave that issue for a future case.)

¶21            In sum, mental disease or defect evidence cannot be admitted
to show that a defendant was less likely to have formed the mens rea
element of a crime even if that evidence corroborates behavioral-tendency
evidence. Here, the trial court correctly precluded Dr. Sullivan from
testifying that Malone suffered from brain damage even if that impairment
made it more likely that he had a character trait for impulsivity.

                                       B.

¶22             Although neither the parties nor the court of appeals
challenged the oft-cited statements in Schantz and Mott that evidence of a
mental disease or defect cannot be admitted to negate mens rea, our
dissenting colleague does. He asserts that Schantz’s rejection of then-draft
MPC § 4.02(1), which makes mental disease or defect evidence admissible
if relevant to whether a defendant acted with the requisite mens rea, was
dicta that Mott mistakenly repeated. See infra ¶¶ 32, 36. We disagree. The
defendant in Schantz raised the issue to this Court by arguing that then-
draft MPC § 4.02(1) supported the propriety of his requested jury
instruction, and this Court thoroughly discussed and resolved the issue by
declining to adopt that provision. 98 Ariz. at 208–13; see also Town of Chino
Valley v. City of Prescott, 131 Ariz. 78, 81 (1981) (defining dictum as “a court’s
statement on a question not necessarily involved in the case”). And even if
Schantz’s rejection of then-draft MPC § 4.02(1) was dicta, this Court has
followed it in other cases, making it precedential. See, e.g., Mott, 187 Ariz.
at 541 (“[T]his court considered and rejected the defense of diminished
capacity in State v. Schantz.” (Citation omitted.)); Malumphy, 105 Ariz. at 202
(“We rejected the doctrine [of diminished responsibility] in State v. Schantz
after an extensive discussion of the subject.” (Citation omitted.)).

¶23           The dissent also argues that Schantz and Mott wrongly
conflated the issues of whether Arizona recognizes a diminished
responsibility defense (excusing criminal acts) with whether mental disease
                                        9
                             STATE v. MALONE
                             Opinion of the Court

or defect evidence is admissible to challenge the prosecution’s proof of
mens rea. See infra ¶¶ 34, 38. We agree that the substantive viability of a
diminished responsibility defense is different from the evidentiary
admissibility of diminished responsibility evidence to refute mens rea. But
for our purposes, this distinction is meaningless. As previously explained,
this Court in Schantz, Mott, and other cases concluded that mental disease
or defect evidence cannot be used to refute mens rea. See supra ¶¶ 15–17.

¶24            Finally, the dissent asserts that Mott incorrectly reasoned that
the legislature’s refusal to adopt MPC § 4.02(1) evidences its rejection of that
provision. See infra ¶ 39 (“The legislature fails to do things for many
reasons.”). The dissent then implies that any such rejection would violate
separation of powers as this Court is empowered by the Arizona
Constitution to develop rules of evidence. Id. This implication is incorrect.

¶25            First, legislative history reflects that the legislature considered
and rejected the evidentiary rule set forth in MPC § 4.02(1). In 1983, the
legislature reformed the insanity defense in the wake of two high-profile
acquittals in murder cases. See Renée Melançon, Note, Arizona’s Insane
Response to Insanity, 40 Ariz. L. Rev. 287, 296–97 (1998). As part of that effort,
the Senate Judiciary Interim Subcommittee on the Insanity Defense
recommended changes. Id. at 296. The subcommittee identified two
mutually exclusive approaches to improving the insanity defense,
including the “mens rea approach,” which reflected MPC § 4.02(1):

       This approach provides that mental disease or defect does not
       constitute a separate defense to a criminal charge, but
       provides for the introduction of expert evidence on the
       defendant’s ability or inability to form the culpable mental
       state required to be convicted of the crime. Thus, the focus is
       on the question of whether or not the defendant acted with
       the requisite culpable mental state . . . .

See Final Report of the Senate Judiciary Interim Subcommittee on the Insanity
Defense, 13, 17 (1982) (hereinafter “Report”). The subcommittee remarked
that this approach had been adopted in Idaho and Montana and, as noted
in the legislative history for the Insanity Defense Reform Act of 1984, Pub.
L. 98–473, 98 Stat. 2057 (1984) (codified as amended at 18 U.S.C. § 17), at the
federal level.1 Report at 17. The legislature quite clearly, albeit implicitly,

1 Idaho and Montana, unlike Arizona, currently follow the MPC § 4.02(1)
approach. See Idaho Code § 18-207 (providing that “[m]ental condition

                                       10
                            STATE v. MALONE
                            Opinion of the Court

rejected the mens rea approach by adopting the alternative approach
currently set forth in § 13-502(A).

¶26            Second, although MPC § 4.02(1) is an evidentiary rule within
this Court’s authority to enact, the dissent overlooks that we have declined
to do so in the fifty-four years since Schantz. There, the Court expressed
“hesitan[ce]” about adopting then-draft MPC § 4.02(1) without the
legislature first adopting the entirety of MPC article 4 which, among other
things, contained involuntary commitment provisions:

       If we accept defendant’s proposal and decide that psychiatric
       evidence of a mental disease or defect is relevant to prove that
       a defendant did not have a state of mind which is an element
       of the offense, the jury would be put to the compulsion of
       releasing upon society many dangerous criminals who
       obviously should be placed under confinement.

98 Ariz. at 212–13. The Mott Court similarly declined to adopt MPC
§ 4.02(1) after considering legislative policy. 187 Ariz. at 541 (“Because the
legislature has not provided for a diminished capacity defense, we have
since consistently refused to allow psychiatric testimony to negate specific
intent.”); see also State v. Laffoon, 125 Ariz. 484, 486 (1980) (“Since the
legislature has not seen fit to provide for a defense of diminished
responsibility, we have consistently declined to allow psychiatric testimony
to negate specific intent.”).

¶27           Although this Court is constitutionally empowered to
promulgate evidentiary rules, we can elect to defer to legislative policy. See
Readenour v. Mario Power Shovel, a Div. of Dresser Indus., Inc., 149 Ariz. 442,
446 (1986) (“Under our constitutional rule-making power we cannot let the
legislature define what is relevant; however, when it is appropriate we may
defer to legislative decisions regarding the use or exclusion of relevant
evidence to promote substantive goals of public policy such as accident
prevention.”). For decades, this Court has deferred to perceived legislative


shall not be a defense to any charge of criminal conduct” but “[n]othing
herein is intended to prevent the admission of expert evidence on the issue
of any state of mind which is an element of the offense, subject to the rules
of evidence”); Mont. Code. Ann. § 46-14-102 (“Evidence that the defendant
suffered from a mental disease or disorder or developmental disability is
admissible to prove that the defendant did or did not have a state of mind
that is an element of the offense.”).
                                      11
                             STATE v. MALONE
                             Opinion of the Court

policy to not permit the admission of mental disease or defect evidence to
refute mens rea. Unlike the dissent, we decline to reexamine those cases
here when the parties have failed to brief or argue the issue, and any change
would not result in reversible error. See, e.g., State ex rel. Brnovich v. City of
Tucson, 242 Ariz. 588, 599 ¶ 45 (2017) (“We generally do not reach out to
decide important constitutional issues or to upset established precedent
when no party has raised or argued such issues.”).

                                CONCLUSION

¶28          We vacate the court of appeals’ opinion and affirm Malone’s
convictions and sentences.




                                       12
                         STATE v. MALONE
                CHIEF JUSTICE BALES, Dissenting in Part
                    and Concurring in the Judgment

BALES, C.J., dissenting in part and concurring in the judgment.


¶29             I agree with the court of appeals that, based on our decision
in State v. Christensen, 129 Ariz. 32 (1981), and Arizona Rule of Evidence 404,
a defendant may offer evidence of brain damage to support a claim that he
has a character trait for impulsivity. Thus, I respectfully dissent from the
majority’s holding that such evidence is categorically barred by our
decisions in State v. Mott, 187 Ariz. 536 (1997), and State v. Schantz, 98 Ariz.
200 (1965). Because I also agree with the court of appeals that any error in
precluding such evidence here was harmless, I concur in the judgment
affirming Malone’s convictions and sentences.


¶30            Our decisions regarding the admissibility of impulsivity
evidence are, as the court of appeals charitably noted, “nuanced.” State v.
Malone, 245 Ariz. 103, 107 ¶ 12 (App. 2018). Our caselaw in this area is
opaque, largely because Mott and Schantz were poorly reasoned and
confusingly worded. We should take this opportunity to clarify the scope
of Mott and Schantz instead of using their rickety foundation to erect a
barrier to relevant evidence.


¶31            Setting aside Mott and Schantz, the evidentiary issue in this
case would be straightforward. Rule 404(a) allows a defendant to offer
evidence of a pertinent character trait, and since Christensen we have
recognized that this rule allows a defendant to show that he possesses a
trait of acting impulsively, and thus it was less likely that he acted with
premeditation. See 129 Ariz. at 34-35. Subject to Rules of Evidence 702
through 705, experts - including mental health experts - may present
evidence to support a defendant’s claim that he possesses a character trait
for impulsivity. See State v. Leteve, 237 Ariz. 516, 524 ¶ 24 (2015). Evidence
that a defendant has brain damage of a type that makes it more likely he
acted impulsively is obviously relevant to whether he has the character
trait, and would be admissible under Rules 401 (defining “relevant”
evidence) and 402 (noting general rule of admissibility), unless it is
precluded by other applicable law or its probative value is substantially
outweighed by the danger of confusing the issues, misleading the jury, or
other concerns noted in Rule 403.


¶32          The issue thus becomes whether Schantz or Mott bars the
admission of proof of brain damage to support a defendant’s claim to have

                                      13
                         STATE v. MALONE
                CHIEF JUSTICE BALES, Dissenting in Part
                    and Concurring in the Judgment

a character trait for impulsivity. Neither case decided this issue and we
should not extend their dicta to preclude such evidence.


¶33            In Schantz, the defendant argued that the jury should have
been instructed to acquit on a charge of second degree murder unless it was
“satisfied beyond a reasonable doubt that the accused . . . was mentally
capable of entertaining, and did entertain,” an intent to kill. 98 Ariz. at 205
n.1. Because the crime of second degree murder did not necessarily require
proof of an intent to kill, id. at 211-12, the defendant instead urged the Court
to require this instruction based on the “diminished capacity defense” and
then-draft § 4.02(1) of the Model Penal Code (MPC), which allowed the
admission of evidence of mental disease or defect when relevant to prove
whether the defendant had “a state of mind which is an element of the
offense,” id. at 208. The requested instruction would have directed an
acquittal if the jury was convinced the defendant lacked the mental capacity
to form an intent to kill. Id. at 205 n.1.


¶34            The defendant’s argument conflated two separate issues. The
first - and the only issue presented in Schantz - was whether Arizona
recognizes a substantive defense of diminished capacity. One version of
that defense, as Schantz recognized, was reflected in draft MPC § 4.01(1), as
it relieves a defendant of criminal responsibility not only if he is insane
under the M’Naghten test, but also if he “lacks substantial capacity . . . to
conform his conduct to the requirements of the law” due to a mental disease
or defect. Whether to recognize such a defense, however, is distinct from
the second issue - the admissibility of evidence of mental disease or defect
to prove whether the defendant acted with the mental state required for the
offense, an issue addressed in MPC § 4.02(1). See United States v. Pohlot, 827
F.2d 889, 897 (3d Cir. 1987). Unfortunately, this Court echoed the
defendant’s confusion of these issues in its opinion in Schantz and would
do so again in Mott.


¶35            Schantz recognized that the “diminished capacity” defense as
reflected in the MPC focuses on whether “an accused lacks the capacity to
conform his conduct to the requirements of law,” 98 Ariz. at 208, and
expressly held that we “do not accept § 4.01 of the [MPC] as the test for
criminal responsibility in this state,” 98 Ariz. at 210-11. The Court noted
that the defendant’s proposed instruction could place the jury in “an almost
unresolvable dilemma,” as it would instruct them to acquit if they found
the defendant incapable of forming an intent to kill, while the court would

                                      14
                         STATE v. MALONE
                CHIEF JUSTICE BALES, Dissenting in Part
                    and Concurring in the Judgment

otherwise instruct them that they need not find such an intent to convict.
Id. at 212.


¶36            In dicta, the Court also rejected the defendant’s reliance on
MPC § 4.01(2), observing that article 4 of the MPC is a “comprehensive
scheme” and that the Court lacked constitutional authority to adopt it as
Arizona law. Id. at 212-13; cf. id. at 216 (McFarland and Udall, JJ., specially
concurring) (noting discussion of MPC was unnecessary to ruling). The
Court concluded by noting that “[i]f we accept defendant’s proposal and
decide that psychiatric evidence of a mental disease or defect is relevant to
prove that a defendant did not have a state of mind which is an element of
the offense, the jury would be put to the compulsion of releasing upon
society many dangerous criminals who obviously should be placed under
confinement.” Id. at 213. The “proposal” referenced in these remarks was
the requested instruction that “permit[ed] the jury to find the defendant not
guilty of second degree murder if he was suffering from a mental
impairment, defect, disorder, or deficiency so as to be incapable of
entertaining malice aforethought, the intent to kill.” Id. at 207.

¶37          Schantz was correct as to the issue it decided - Arizona does
not recognize a defense of “diminished responsibility” that relieves a
defendant of criminal responsibility if a mental disease or defect renders
him incapable of forming a mental state. Similarly, the Court was correct
in suggesting that evidence of a mental disease or defect is not admissible
to show a defendant lacks the capacity to form a requisite mental state, as
allowing such evidence would be tantamount to allowing a diminished
capacity defense. Indeed, the rejected instruction in Schantz would have
told the jury it could consider such evidence “to negate the accused’s
capacity to entertain the required malice aforethought, specific intent or
knowledge.” Id. at 205 n.1 (emphasis added). Only in this respect did
Schantz suggest that evidence of mental disease or defect is inadmissible to
“negate” a required mental state.


¶38           Mott followed Schantz both in rejecting a defense of
diminished capacity and in confusing that issue with the admissibility of
evidence to show whether a defendant acted with a requisite mental state.
In Mott, the Court upheld the exclusion of expert testimony regarding
“battered woman syndrome” offered to establish that the “defendant was
not capable of forming the requisite mental state of knowledge or intent.”
187 Ariz. at 539-40; see also id. at 538 (noting proffered testimony was that

                                      15
                         STATE v. MALONE
                CHIEF JUSTICE BALES, Dissenting in Part
                    and Concurring in the Judgment

“as a battered woman, she was unable to form the requisite mental state”);
id. at 540 n.4 (noting that defendant had offered evidence “to demonstrate
that she did not have the capacity to form the requisite mental state”); id. at
543 (noting evidence was offered to show “defendant was not capable of
forming the specific intent required”). Mott, like Schantz, characterized
such evidence as being offered “to negate the mens rea element of the
crime.” Id. at 540. Significantly, when Mott overruled State v. Gonzales, 140
Ariz. 349 (1984), “to the extent it allowed evidence of a defendant’s
diminished mental capacity as a defense to a charged crime,” the Court
emphasized that Gonzales involved expert testimony that a defendant, as
result of brain damage, “did not and could not have” the specific intent
required for the crime. 187 Ariz. at 544 (quoting Gonzales, 140 Ariz. at 350-
51). Rejecting evidence of a mental disease or defect when offered to show
a defendant lacks the capacity to form a requisite mental state is, as noted
above, logically consistent with rejecting a diminished capacity defense. If
incapacity is not a substantive defense, then evidence offered to prove
incapacity is irrelevant and inadmissible for that purpose.

¶39             Mott, like Schantz, said more than was needed to resolve the
issue before the Court, and some of its extraneous comments were unclear
or simply wrong. Noting that Arizona’s legislature had declined to adopt
the defense of diminished capacity as reflected in the MPC, the Court then
observed that this action implied a decision “not to adopt” MPC § 4.02(1),
which in turn “evidences its rejection of the use of psychological testimony
to challenge the mens rea element of a crime.” 187 Ariz. at 540. This passing
observation has multiple flaws. It once again confuses recognition of the
diminished capacity defense with the issue of admissibility. See Pohlot, 827
F.2d at 897 (noting that “[p]roperly understood, [MPC § 4.02] is therefore
not a defense at all but merely a rule of evidence”). It also incorrectly
suggests that rejecting the defense implies a general bar on admissibility,
and while Mott (like Schantz) correctly recognizes that it is the legislature’s
province to define crimes and recognize substantive defenses, these
opinions overlook that the Arizona Constitution empowers this Court to
develop rules of evidence. Ariz. Const. art. 6, § 5(5); see also State ex rel.
Collins v. Seidel, 142 Ariz. 587, 590 (1984). The legislature fails to do things
for many reasons, and its failure to adopt MPC § 4.02 does not imply that it
intended prospectively to categorically bar certain types of evidence
relevant to whether a defendant acted with the mental state the legislature
has said is necessary for the commission of an offense.




                                      16
                         STATE v. MALONE
                CHIEF JUSTICE BALES, Dissenting in Part
                    and Concurring in the Judgment

¶40           In short, neither Schantz nor Mott addresses the admissibility
of evidence of mental disease or defect to show that a defendant has a
character trait for impulsivity as distinct from the use of such evidence to
show that a defendant lacked the capacity to form a requisite mental state.
Barring the latter does not require also barring the former. Although Mott
contains some vague language about rejecting the use of psychological
evidence to challenge or “negate” mens rea, 187 Ariz. at 540, 544, these
statements were made in the context of precluding evidence that a
defendant lacked the capacity to form a specific intent. If those statements
were applied more broadly, they would suggest that the expert testimony
allowed in Christensen and Leteve should have been barred.

¶41             The majority does not identify good reasons for extending
Schantz and Mott to preclude evidence of brain damage when offered to
support a claim that the defendant has an impulsive character. Though the
Court now recognizes that we have previously conflated a defense of
diminished capacity with the use of mental defect evidence more broadly,
it declines to alter course. See supra ¶¶ 22, 26. We should not infer from the
legislature’s rejecting a defense of diminished capacity - or its not adopting
an evidentiary rule - some implicit intent generally to preclude evidence
relevant to whether a defendant acted with a requisite mental state.

¶42           If defendants can offer evidence that they have an impulsive
character trait, there is no logical reason to categorically bar them from
offering evidence of brain damage that is associated with such a trait.
Excluding such evidence would be particularly unfair when the
prosecution challenges the defendant’s claim to have an impulsive
character. Moreover, because our understanding of the relation between
brain physiology and behavior (including “character traits”) is incomplete
and still evolving, instead of relying on Schantz and Mott to categorically
bar brain damage evidence, I would trust our trial judges to decide its
admissibility and jurors to assess its weight under our Rules of Evidence.


¶43           Our evidentiary rules expressly contemplate the admission of
evidence that can be considered for some purposes but not others. Ariz. R.
Evid. 105. Thus, concerns about jurors considering the evidence for
purposes other than proof of a trait for impulsivity can be addressed
through limiting instructions, and we generally presume that jurors can
and will follow such instructions. State v. Ovante, 231 Ariz. 180, 186 ¶ 24
(2013). If such evidence raises substantial concerns about confusing or
misleading the jury, it may be excluded pursuant to Rule 403.

                                     17
                         STATE v. MALONE
                CHIEF JUSTICE BALES, Dissenting in Part
                    and Concurring in the Judgment



¶44           Although I do not support the majority’s blanket bar on brain
damage evidence to support a claimed character trait for impulsivity, it is
not necessary here to decide whether the evidence of Malone’s brain
damage was properly excluded under Rule 403 or for other reasons. As
noted by the court of appeals, any error in excluding this evidence was
harmless, given the other admitted evidence showing that Malone had a
character trait for impulsivity and the fact that the State did not challenge
this evidence or the existence of the character trait. Accordingly, I concur
in the Court’s judgment.




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