By Lawrence Hurley
WASHINGTON (Reuters) - The U.S. Supreme Court, siding with a death row inmate, ruled on Thursday that Pennsylvania's former top judge should have stepped aside when his court heard a case in which he earlier as a prosecutor had authorized seeking capital punishment.
The Supreme Court ruled 5-3 in favor of Terrance Williams, convicted in the 1984 bludgeoning murder of a 56-year-old man in Philadelphia. Williams, 18 at the time of the crime, said the man had sexually abused him as a youth.
Williams will now get a new hearing before Pennsylvania's Supreme Court to challenge his death sentence.
The justices threw out a 2014 ruling by the Pennsylvania Supreme Court that upheld the death sentence given to Williams. Williams' appeal focused on the actions of Ronald Castille, who served as Philadelphia's district attorney when Williams was convicted and was Pennsylvania's chief justice and served on the state Supreme Court when it affirmed the death sentence.
"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," Justice Anthony Kennedy wrote for the court.
Kennedy was joined by the court's four liberal justices in the ruling, with conservative justices John Roberts, Clarence Thomas and Samuel Alito dissenting.
As district attorney, Castille gave the go-ahead for the prosecution to pursue the death penalty against Williams, who separately was convicted in a second murder. In 2014, Castille served on the state Supreme Court when it unanimously reinstated the death penalty against Williams after a judge had thrown out capital punishment in the case due to prosecutorial misconduct.
Castille, now retired from the bench, was elected to the state's high court in 1993 after touting his record of sending criminals to death row. Castille refused a request by Williams' lawyers to recuse himself when the case went before the state Supreme Court.
Williams, a former star high school quarterback, was convicted of bludgeoning the man and later setting the body on fire. Prosecutors claimed the killing was tied to a robbery.
During the appeals process, Williams' lawyers introduced evidence that he had been sexually abused by the man he killed, a church deacon. A lower court then found that prosecutors working for Castille had withheld evidence about the man's sexual abuse of boys.
There is currently a death penalty moratorium in Pennsylvania imposed by Governor Tom Wolf.
The justices heard arguments in the case on Feb. 29.
(Reporting by Lawrence Hurley; Editing by Will Dunham)