State of Arizona v. William Craig Miller

Summary

The Supreme Court of Arizona reversed an order granting William Craig Miller a new penalty-phase trial. The court held that Miller failed to establish that trial or appellate counsel performed deficiently by not challenging a widely used jury instruction defining the mental-impairment mitigating circumstance. The court also concluded that Miller failed to demonstrate prejudice under Strickland because other instructions allowed consideration of his mental-health evidence and the totality of the aggravating and mitigating circumstances did not establish a reasonable probability of a different result.

Holdings

1. Miller failed to prove that trial or appellate counsel's failure to challenge the instruction fell below an objective standard of reasonableness under prevailing professional norms. The instruction's use of the word "prevented" was erroneous, but the error was not obvious or grievous on this record, and the instruction was widely used and had not been called into question at the time of trial and appeal.
2. Miller failed to show a reasonable probability that, absent counsel's alleged errors, the jury would have returned life-sentence verdicts or the Arizona Supreme Court would have vacated the death sentences and ordered a new penalty phase.
3. The post-conviction court abused its discretion by granting relief without adequately investigating or weighing the facts necessary to determine prejudice under Strickland.

Questions Presented

1. Whether trial and appellate counsel provided constitutionally deficient performance by failing to challenge the pre-2016 jury instruction defining the statutory significantly-impaired-capacity mitigator.
2. Whether Miller was prejudiced under Strickland by counsel's failure to challenge the instruction.
3. Whether the post-conviction court properly granted relief without weighing the aggravating circumstances against the totality of the mitigating evidence.

Disposition

reversed