Payton v. Cullen, 658 F.3d 890

Payton raped and murdered Pamela Montgomery and stabbed Patricia Pensinger and her son Blaine Pensinger in May 1980; Payton's wife testified his clothes and hands were bloodied when he returned home.
He was convicted of first-degree murder and rape and sentenced to death; California Supreme Court affirmed on direct appeal and on habeas review.
Payton pursued federal habeas corpus; district court granted summary judgment on guilt phase and certain penalty-phase issues, with multiple claims unresolved and cross-appeals filed.
Panel reversed on factor (k) issue and affirmed other claims; en banc proceedings occurred; Supreme Court eventually held AEDPA applied and results varied on factor (k); subsequent remand addressed remaining claims not previously resolved.
On remand, district court denied the remaining claims; Payton sought COA and challenged California's lethal-injection protocol as premature; court dismissed the protocol challenge as premature and affirmed the judgment on other claims.
This court considers all claims as if properly before it, dismisses the lethal-injection challenge as premature, and affirms the district court’s judgment on the merits.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Lethal injection protocol premature challenge	Payton argues the protocol violates evolving due-process standards.	State contends the challenge is premature or not ripe at the time of decision.	Premature; affirmed dismissal of protocol challenge.
Ineffective assistance for failure to investigate mitigation (penalty phase)	Merwin failed to investigate/present social history and PTSD evidence.	Counsel reasonably investigated, consulted experts, and pursued available mitigation.	No deficient performance or prejudice established; claim rejected.
Brady violation regarding informant Escalera's status	Prosecutor failed to disclose Escalera's government-agent role; new evidence shows possible perjury.	New evidence insufficient to show a reasonable probability of different outcome; impeachment limited.	No reasonable probability of different outcome; Brady claim rejected.
PTSD mitigation claim (uncertified issues)	Payton's PTSD evidence should have been investigated and presented at penalty stage.	Counsel's investigation was reasonable; PTSD evidence was not substantiated as a valid defense at the time.	Uncertified issue; no relief; evidence insufficient to show prejudice.
Cumulative error claim (uncertified issue)	Cumulative errors warrant reversal.	Aggregate errors do not render trial fundamentally unfair.	No reversible cumulation; no relief on cumulative-error grounds.

Rhoades v. Henry, 638 F.3d 1027 (9th Cir. 2011) (contextual comparison of mitigating evidence effects)
Rompilla v. Beard, 545 U.S. 374 (U.S. 2005) (mitigation evidence and prejudice analysis in capital cases)
Wiggins v. Smith, 539 U.S. 510 (U.S. 2003) (duty to investigate and present mitigation evidence)
Porter v. McCollum, 130 S. Ct. 447 (U.S. 2010) (deficient investigation of PTSD-like mitigation evidence)
Kyles v. Whitley, 514 U.S. 419 (U.S. 1995) ( Brady/false-impeachment material standard)
Strickland v. Washington, 466 U.S. 668 (U.S. 1984) (ineffective-assistance standard)
Lambright v. Stewart, 241 F.3d 1201 (9th Cir. 2001) (preference for evaluating PTSD-type mitigation in context)
Chambers v. Mississippi, 410 U.S. 284 (U.S. 1973) (due process fairness and admissibility of evidence)
Parle v. Runnels, 505 F.3d 922 (9th Cir. 2007) (cumulative-error concepts in habeas corpus)
Pinholster v. Ayers, 131 S. Ct. 1388 (U.S. 2011) (limitations on consideration of new evidence on habeas review)
Williams v. Taylor, 529 U.S. 362 (U.S. 2000) (mitigation evidence and prejudice analysis)