In Sears v. Upton, No. 09-8854, a capital murder prosecution, the Court vacated the Georgia Supreme Court's affirmance of the denial of post-conviction relief, holding that the state post-conviction trial court failed to apply the correct prejudice inquiry the Court had established for evaluating defendant's ineffective assistance claim, because 1) the court curtailed a more probing prejudice inquiry because it placed undue reliance on the assumed reasonableness of counsel's mitigation theory; and 2) the Court never limited the prejudice inquiry under Strickland to cases in which there was only "little or no mitigation evidence" presented.
As the Court wrote: "According to an expert who testified during state post-conviction relief, petitioner Demarcus A. Sears performs at or below the bottom first percentile in several measures of cognitive functioning and reasoning. The cause of this abnormality appears to be significant frontal lobe brain damage Sears suffered as a child, as well as drug and alcohol abuse in his teens. But because--in the words of the state trial court--his counsel conducted a penalty phase investigation that was "on its face . . . constitutionally inadequate," App. to Pet. for Cert. 27B, evidence relating to Sears' cognitive impairments and childhood difficulties was not brought to light at the time he was sentenced to death."