Marcellus Williams v. Donald Roper, 695 F.3d 825

Marcellus Williams was convicted of first‑degree murder and sentenced to death in Missouri after a trial that included extensive evidence of his prior criminal history and victim impact testimony.
During penalty phase, defense presented family history and character testimony; the state offered a large criminal-history and aggravation case; Williams attempted to present mitigation but some evidence was deemed inadmissible.
Williams’s postconviction claim alleged trial counsel failed to adequately investigate and present mitigating background, including abuse and mental illness, which could have altered the sentencing outcome.
The state postconviction court found the mitigation theory presented, a ‘family man’ strategy, was reasonable and that undiscovered evidence would not have changed the result; the Missouri Supreme Court affirmed.
The district court granted habeas relief on the penalty‑phase prejudice claim, but the Eighth Circuit reversed, holding the state court’s prejudice finding within AEDPA deference and Strickland standards.
The Supreme Court of Missouri record showed abundant aggravation and limited mitigating evidence; the federal district court’s prejudice finding was reconsidered under AEDPA’s deferential review.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the state court’s prejudice determination was an unreasonable application of Strickland	Williams: prejudice was established; undiscovered mitigators undermined confidence in the verdict	State: no prejudice; strategy and evidence balance supported death sentence	Not prejudiced under AEDPA; decision not unreasonable
Whether AEDPA’s doubly deferential standard applies to a Strickland prejudice ruling	Defer to state court’s explicit Strickland prejudice ruling under AEDPA	Apply de novo review if state court misapplied Strickland	Court applies doubly deferential standard; would uphold state court if reasonable under Strickland
Whether undiscovered mitigating evidence could have changed the sentencing outcome	New abuse/mental‑illness evidence could have warranted different balance of aggravation/mitigation	Evidence would have been outweighed by aggravation; defense strategy would not have changed outcome	Not a reasonable probability of a different sentencing outcome

Wiggins v. Smith, 539 U.S. 510 (U.S. 2003) (necessity of thorough investigation to support strategy)
Porter v. McCollum, 558 U.S. 30 (U.S. 2009) (mitigation outweighs aggravation; prejudice assessment varies)
Cullen v. Pinholster, 131 S. Ct. 1388 (U.S. 2011) (AEDPA deference; mitigation evidence value and admission risks)
Woodford v. Visciotti, 537 U.S. 19 (U.S. 2002) (deference when aggravating factors are overwhelming)
Rompilla v. Beard, 545 U.S. 374 (U.S. 2005) (investigation duty; effect of mitigating evidence)
Harrington v. Richter, 131 S. Ct. 770 (U.S. 2011) (standard for reviewing reasonableness of state‑court decisions under AEDPA)
Premo v. Moore, 131 S. Ct. 733 (U.S. 2011) (unexplained state court decisions; focus on reasonableness of prejudice ruling)
Johnson v. Sec’y, Dep’t of Corr., 643 F.3d 907 (11th Cir. 2011) (de novo review where state court’s prejudice ruling is unreasonable)
Link v. Luebbers, 469 F.3d 1197 (8th Cir. 2006) (preserves de novo prejudice review where appropriate)
Penry v. L ynaugh, 492 U.S. 302 (U.S. 1989) (mitigation relevance for moral culpability in capital cases)