Williams v. Pennsylvania, 579 U.S. ___, 136 S. Ct. 1899 (Jun. 9, 2016)

Due process required that a Pennsylvania Supreme Court Justice recuse himself from the capital defendant’s post-conviction challenge where the justice had been the district attorney who gave his official approval to seek the death penalty in the case. The Court stated: “under the Due Process Clause there is an impermissible risk of actual bias when a judge earlier had significant, personal involvement as a prosecutor in a critical decision regarding the defendant’s case.” It went on to hold that the justice’s authorization to seek the death penalty against the defendant constituted significant, personal involvement in a critical trial decision. Finally, it determined that an unconstitutional failure to recuse constitutes structural error even if the judge in question did not cast a deciding vote; as such the error was not subject to harmless error review.