Sears v. Upton, USSC No. 09-8854, 6/29/10
The state court concluded that in this death penalty case, counsel failed to conduct more than a cursory penalty-phase investigation (and thus failed to determine that Sears suffered significant frontal lobe damage and had endured significant childhood abuse). However, the state court also concluded that it couldn’t find prejudice because counsel adduced some mitigation — this latter conclusion, the Court now holds, plainly violated normative review of effective-assistance claims.
We certainly have never held that counsel’s effort to present some mitigation evidence should foreclose an inquiry into whether a facially deficient mitigation investigation might have prejudiced the defendant. …
A proper analysis of prejudice under Strickland would have taken into account the newly uncovered evidence of Sears’ “significant” mental and psychological impairments, along with the mitigation evidence introduced during Sears’ penalty phase trial, to assess whether there is a reasonable probability that Sears would have received a different sentence after a constitutionally sufficient mitigation investigation. See Porter, supra, at ___ (slip op., at 11); Williams, supra, at 397–398; Strickland, supra, at 694. It is for the state court—and not for either this Court or even JUSTICE SCALIA—to undertake this reweighing in the first instance.