By Richard Wolf

A closely divided Supreme Court ruled Thursday that a Pennsylvania judge violated a convicted murderer’s constitutional rights by voting to uphold his death sentence following a prosecution he supervised as district attorney.

Justice Anthony Kennedy, backed by the court’s four more liberal members in a 5-3 decision, said former Pennsylvania Supreme Court Chief Justice Ronald Castille created an impermissible risk of bias by serving as both accuser and adjudicator in the case of Terrance Williams — even though the murder was in 1984, and the ruling at issue came three decades later in the prisoner’s fifth attempt to reverse the 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 proceedings rises to an unconstitutional level,” Kennedy wrote.

The case was sent back so that Williams can have another shot at avoiding the death sentence Castille authorized his prosecutors to seek in 1986. Williams was convicted of killing two men who had sexually abused him as a child. His execution was blocked about 25 years later because of suppressed material but was later reinstated.

Chief Justice John Roberts, along with Justices Samuel Alito and Clarence Thomas, dissented. Roberts said Castille was not deciding the same question he faced when supervising Philadelphia prosecutors three decades earlier, though he inferred it may not have been “appropriate” for Castille to participate in the later case.

Thomas went further, arguing that the due process rights of someone already convicted are less than those of the accused. “Whatever those rights might be, they do not include policing alleged violations of state codes of judicial ethics in post-conviction proceedings,” he said.

The case presented the eight justices with an uncomfortable subject: how to police their own profession. Last year, they were divided 5-4 over Roberts’ ruling that Florida — and other states, by extension — can bar judges and judicial candidates from soliciting campaign donations.

And in 2009, the court ruled 5-4 that a West Virginia Supreme Court justice should have recused himself from a case involving a company whose CEO had contributed to the judge’s campaigns.

In the Pennsylvania case, Castille — a decorated Marine who nearly won a primary for mayor of Philadelphia in 1991 as a Republican — sought the death penalty for Williams. He boasted during his campaign for a seat on the Pennsylvania Supreme Court in 1993 that he had sent 45 people to death row.

The ruling was applauded by judicial watchdog groups such as Fix the Court, which advocates for tighter standards on recusals, as well as liberal interest groups such as the Constitutional Accountability Center.

“In a time when the nation is dealing with trumped-up assertions of judicial bias based on race and ethnicity, this case provided a clear-cut example of what judicial bias really is,” said the center’s president, Elizabeth Wydra.