On June 9, 2016, the Supreme Court decided Williams v. Pennsylvania. Terrance Williams was convicted and sentenced to death for the robbery and murder of Amos Norwood. The Supreme Court of Pennsylvania affirmed Williams’ conviction and sentence, and his initial attempts to obtain state postconviction relief failed. His subsequent petition for federal habeas relief also failed. He again sought post-conviction penalty-related relief in state court and prevailed in the Court of Common Pleas on a claim of unlawful evidence suppression. On appeal, however, the Pennsylvania Supreme Court reversed the grant of relief and lifted the stay of execution (though a temporary reprieve was later granted by the governor for other reasons). The Chief Justice of the Pennsylvania Supreme Court, Ronald Castille, who had joined the opinion reversing the grant of relief to Williams, had also been the District Attorney for Philadelphia during Williams’ trial, sentencing, and appeal. In that capacity, Castille had authorized his office to seek the death penalty for Williams. Williams had moved to have Chief Justice Castille recuse himself from hearing the appeal of post-conviction relief, but Castille declined to do so. -- The central question before the U.S. Supreme Court was whether Justice Castille’s denial of the recusal motion and his subsequent judicial participation violated the Due Process Clause of the Fourteenth Amendment. By a vote of 5-3, the Supreme Court vacated the decision of the Pennsylvania Supreme Court and remanded the case. Justice Kennedy delivered the opinion of the Court, which held that under the Due Process Clause, where a judge has had an earlier significant, personal involvement as a prosecutor in a critical decision in the defendant’s case, the risk of actual bias in the judicial proceeding rises to an unconstitutional level. Justices Ginsburg, Breyer, Sotomayor, and Kagan joined Justice Kennedy’s majority opinion. Chief Justice Roberts filed a dissenting opinion, in which Justice Alito joined. Justice Thomas also filed a dissenting opinion. -- To discuss the case, we have Cassandra Burke Robertson, who is Professor of Law, Laura B. Chisolm Distinguished Research Scholar, and Director, Center for Professional Ethics at Case Western Reserve University School of Law.