In the 2009 case of DeMarcus Ali Sears v. Stephen Upton, Warden, the United States Supreme Court was asked to review a decision by the Georgia Supreme Court regarding whether or not Sears had received ineffective assistance from his trial counsel during sentencing for a murder conviction. The main issue was that his lawyer failed to present mitigating evidence about Sears' troubled background and mental health issues which could have potentially led to a lesser sentence than death. The Georgia court ruled against him using an analysis inconsistent with established federal law on evaluating claims of ineffective legal representation in capital cases. However, upon review, the US Supreme Court vacated this judgment and remanded it back to lower courts for further proceedings consistent with its opinion because they found that state court's decision involved an unreasonable application of clearly established Federal Law.

In the dissenting opinion for DeMarcus Ali Sears v. Stephen Upton, Warden, Justice Scalia disagreed with the majority's decision to grant habeas relief based on ineffective assistance of counsel during sentencing. He argued that there was no reasonable probability that a competent attorney presenting mitigating evidence would have changed the outcome of Sears' sentence. The defense had already presented substantial mitigation evidence and further details about his troubled upbringing wouldn't have made a significant difference in light of his brutal crime. Furthermore, he contended that Georgia Supreme Court didn’t apply an unreasonable standard when it concluded that Sears failed to show prejudice from any alleged deficiency in counsel’s performance at sentencing phase.