State of Arizona v. Eric Boyston, 231 Ariz. 539

Background

Boyston was convicted by a jury of three counts of first-degree murder and two counts of attempted first-degree murder; he was sentenced to death for the murders and imprisonment for the attempts.
The killings occurred in Mary Boyston’s apartment complex: Alexandria was shot, Mary and her son Alexander and her great-aunt Shirley were killed or injured, and Timothy Wright was stabbed; the shootings followed a dispute over Boyston’s living arrangements.
A prescreening IQ test yielded 59, while later tests showed 64–65; the court appointed multiple experts to determine whether Boyston had mental retardation under A.R.S. § 13-753.
The State’s expert Dr. Seward concluded Boyston did not have significant adaptive- or intellectual-deficits and malingered; the trial court credited Seward over the defendant’s experts.
Boyston argued the trial court abused its discretion on expert qualifications, testing methods, and the ultimate mental retardation ruling; the court rejected these challenges and upheld the ruling.
During the guilt and penalty phases, the court instructed on first- and second-degree murder, allowed evidence of intoxication in the guilt phase only insofar as it related to premeditation, and later reviewed aggravating circumstances and mitigation during appellate review of the death sentences.

Issues

Issue	Plaintiff's Argument	Defendant's Argument	Held
Qualification of State's mental retardation expert	Boyston contends Seward lacked § 13-753(K)(2) experience.	Boyston argues Seward met the five-year-experience requirement and was qualified.	Court: Seward was qualified; the five-year experience requirement was satisfied.
Evaluation methods and current testing standards	Boyston asserts Seward failed to use currently accepted testing procedures.	Seward followed current standards and relied on valid data from others’ tests.	Court: Seward's methods complied with current standards; admission upheld.
Trial court's mental retardation ruling	Boyston argues clear and convincing evidence of mental retardation was shown.	State disputes substantial impairment in adaptive functioning and pre-age-18 onset.	Court: No clear and convincing proof of mental retardation; ruling affirmed.
Pre-meditation and voluntary intoxication evidence	§ 13-503 bars consideration of intoxication when proving premeditation; Boyston relies on Atkins and related authorities.	Premeditation is a mental-state element; intoxication may be precluded in guilt phase.	Court: § 13-503 precludes intoxication as to premeditation; law consistent with due process and equal protection.
Sufficiency of proof of premeditation for killings	State presented substantial evidence of premeditation for Mary and Timothy’s murders.	Boyston contends evidence was insufficient or speculative.	Court: Substantial evidence supports premeditation for all three murders; no reversible error.

Key Cases Cited

State v. Grell (Grell II), 212 Ariz. 516 (Ariz. 2006) (broad discretion in weighing mental-health evidence; abuse of discretion standard)
State v. Grell (Grell III), 231 Ariz. 153 (Ariz. 2013) (Atkins framework; burden of proof for intellectual disability remains clear and convincing)
State v. Thompson, 204 Ariz. 471 (Ariz. 2003) (premeditation defined; mental-state analysis in first-degree murder cases)
Beck v. Alabama, 447 U.S. 625 (U.S. 1980) (requiring jury option between first-degree murder and lesser offense to avoid arbitrariness)
State v. Kuhs, 223 Ariz. 376 (Ariz. 2010) (premeditation and mental-state considerations in capital cases)
State v. Cota, 229 Ariz. 136 (Ariz. 2012) (parole and release consequences in capital-sentencing review)
State v. Ovante, 231 Ariz. 180 (Ariz. 2013) (continued discussion of premeditation and evidentiary standards in capital cases)
State v. Nelson, 229 Ariz. 180 (Ariz. 2012) (standard of review for death-penalty appellate cases)