State v. Buot, 232 Ariz. 432

Buot (defendant) swerved his SUV into oncoming traffic, causing a fatal head-on collision; he later admitted to his wife and another witness that he intentionally swerved.
Before the crash, Buot allegedly told his wife during an argument he would drive into oncoming traffic; other witnesses testified to prior similar threats.
The State charged Buot with second-degree murder (intentional/knowing or reckless conduct manifesting extreme indifference).
At trial the State sought to admit Buot’s prior threats under Ariz. R. Evid. 404(b) to rebut Buot’s defense that the crash was an accident; Buot did not object at trial and agreed to jury instructions permitting use for motive/intent/absence of mistake.
Buot also sought to call a psychiatrist (Dr. Potts) to testify that Buot had a character trait of impulsivity/intermittent explosive disorder to negate the mens rea for second-degree murder; the court limited expert testimony to observations the expert personally made, and Buot did not call Potts.
The trial court convicted Buot of second-degree murder and sentenced him to an aggravated 22-year term; Buot appealed contesting admission of other-act evidence and exclusion/limitation of expert impulsivity testimony.

Issue	Buot's Argument	State's Argument	Held
Admissibility of prior threats (other-act evidence)	Prior threats were unfairly prejudicial and should not be admitted to show propensity	Threats rebutted claim of accident and were admissible for motive, intent, absence of mistake under Rule 404(b)	Admission was not fundamental error; evidence was highly probative and properly limited for non-propensity purposes
Expert testimony that Buot’s impulsivity negated mens rea	Expert could testify to a character trait/impulse-control disorder to show Buot lacked capability to form intent/knowing or recklessness (volitional incapacity)	Arizona law disallows diminished-capacity/volitional-incapacity defenses short of insanity; expert opinion beyond personal observation improperly raises mental-disease/capacity issues	Exclusion/limitation did not violate due process; Arizona does not permit impulsivity evidence to negate mens rea for second-degree murder

State v. Mott, 187 Ariz. 536, 931 P.2d 1046 (1997) (limits on psychiatric evidence to show mens rea; distinguishes insanity from diminished-capacity)
Clark v. Arizona, 548 U.S. 735 (2006) (upheld Arizona’s rules allowing insanity evidence but restricting mental-health evidence offered to negate mens rea; discussed observation-evidence distinction)
State v. Christensen, 129 Ariz. 32, 628 P.2d 580 (1981) (permitted expert testimony about defendant’s tendency to act reflexively rather than reflectively to negate premeditation)
Leland v. Oregon, 343 U.S. 790 (1952) (due process does not require states to recognize irresistible-impulse defense)
State v. Lucero, 223 Ariz. 129, 220 P.3d 249 (2009) (evidence of admissions and contemporaneous threats strongly probative for intent)