Robert Poyson v. Charles Ryan, 879 F.3d 875

Poyson was sentenced to death in 1998 after a six-day trial for three murders and related charges.
The Arizona Supreme Court affirmed the conviction and death sentence on direct review in 2000, independently weighing aggravating and mitigating factors.
Poyson pursued postconviction relief in state court; the state court denied relief and the Arizona Supreme Court summarily denied review in 2004.
Poyson filed a federal habeas petition in 2004; the district court denied relief in 2010 and this court later reviewed the case.
Three issues were certified for review: (i) whether mitigating evidence was evaluated under an unconstitutional causal nexus test, (ii) whether the courts considered his history of substance abuse, and (iii) whether trial counsel provided ineffective assistance during the penalty phase by failing to investigate fetal alcohol spectrum disorder.
The panel ultimately grants relief on the causal nexus claim, denies relief on the substance abuse claim, and finds the penalty-phase ineffectiveness claim procedurally defaulted, remanding for resentencing unless the state corrects the constitutional error or imposes a lawful lesser sentence.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether Arizona’s causal nexus rule improperly excluded mitigating evidence	Poyson argues the Arizona Supreme Court refused to consider childhood/mental-health evidence absent a causal link	Arizona courts weighed mitigating evidence but required a causal connection to the crimes	Yes; the rule violated Eighth/Fourteenth Amendment standards and AEDPA, warranting relief
Whether the history of substance abuse was properly considered as nonstatutory mitigation	Poyson contends the courts failed to consider substance-abuse history as mitigating evidence under Lockett/Eddings	State courts considered but found the evidence lacking and not mitigating	No; no constitutional violation found; evidence failed to prove a mitigating, nonstatutory factor
Whether penalty-phase ineffective assistance claims are procedurally defaulted or exhausted	Poyson alleged trial counsel failed to investigate FASD as mitigation	State courts rejected the claim as new theory not presented in state court; default applies	Procedurally defaulted; federal petition presented a new theory not fairly presented to state courts

Lockett v. Ohio, 438 U.S. 586 (1978) (mitigating evidence must be considered)
Eddings v. Oklahoma, 455 U.S. 104 (1982) (cannot refuse to consider mitigating evidence)
Penry v. Lynaugh, 492 U.S. 302 (1989) (mitigation must be weighed, not ignored)
Tennard v. Dretke, 542 U.S. 274 (2004) (no nexus requirement for mitigating evidence under Eighth Amendment)
Smith v. Texas, 543 U.S. 37 (2004) (per curiam; reaffirmed Eighth Amendment mitigation considerations)
McKinney v. Ryan (en banc), 813 F.3d 798 (2015) (crucial for causal nexus analysis in Arizona mitigation claims)
State v. Brewer, 170 Ariz. 486, 826 P.2d 783 (1992) (illustrative of the unconstitutional causal nexus approach (cited by Arizona court))
State v. Poyson, 198 Ariz. 70, 7 P.3d 79 (2000) (Arizona Supreme Court decision on mitigation and aggravation)
Parker v. Dugger, 498 U.S. 308 (1991) (reweighing of mitigating and aggravating circumstances)
Brecht v. Abrahamson, 507 U.S. 619 (1993) (harmless-error standard for habeas review)