New York Times

WASHINGTON — Not long after he took office as Philadelphia’s district attorney in 1986, Ronald D. Castille made a handwritten note on a subordinate’s memorandum. “Approved to proceed on the death penalty,” Mr. Castille wrote, in neat cursive script, authorizing prosecutors to seek the execution of a young murderer named Terrance Williams.

Later, when Mr. Castille was running for a seat on the Pennsylvania Supreme Court, he said he was reluctant to take a firm public position on the death penalty, fearing it would require his recusal from all capital cases.

“I can certainly say I sent 45 people to death row as district attorney of Philadelphia,” he told a legal newspaper in 1993, adding that voters “sort of get the hint.” Mr. Williams was the first of those 45.

Mr. Castille won the election and served on the State Supreme Court for 21 years, the last seven as chief justice. One of his final acts, about two weeks before he retired at the end of 2014, was to join a unanimous decision reinstating Mr. Williams’s death sentence.

Next month, the United States Supreme Court will hear arguments about whether Mr. Castille should have disqualified himself from hearing Mr. Williams’s appeal, given his involvement in the prosecution. The case, Williams v. Pennsylvania, No. 15-5040, puts the justices in a ticklish spot, as the best arguments against recusal are grounded in their own practices. Individual justices decide for themselves whether their recusal is warranted, just as Mr. Castille had.

That is the right approach, Mr. Castille said last week. “The individual involved should make the decision,” he said. “We leave it up to the individual conscience of the justice.”

In declining to recuse himself from other capital cases over the years, Mr. Castille pointed to the examples of two members of the United States Supreme Court, Justices William H. Rehnquist and Antonin Scalia.

In 1972, Justice Rehnquist, a former Justice Department official, issued a statement justifying his participation in a decision about Army surveillance of domestic political groups even though he had defended the spying program in congressional testimony and had criticized the lawsuit when he was a government lawyer.

In 2004, Justice Scalia explained that he could vote on a case involving the official conduct of Vice President Dick Cheney despite the fact that the two had gone duck hunting together.

Similarly, Mr. Castille said last week, there was no reason for him to recuse himself. “I didn’t try the case,” he said. “I wasn’t really involved in the case except as the leader of the office.”

Moreover, the decision to seek death was straightforward, he said. “This guy had a previous homicide,” Mr. Castille said. “That’s the easiest one, where they have a history of violent crime.”

Mr. Williams committed his first murder when he was 17. A jury spared his life after hearing evidence that he had been sexually abused by the man he killed.

In the second case, by contrast, Mr. Williams testified that he had not known the victim, a 56-year-old man named Amos Norwood, and had not been involved in the murder. In fact, Mr. Williams and a friend, both 18, had robbed Mr. Norwood and beat him to death with a tire iron.

The trial prosecutor said that Mr. Williams had killed Mr. Norwood “for no other reason but that a kind man offered him a ride home.”

In 2012, reviewing one of Mr. Williams’s many challenges to his death sentence, a state trial judge said there was another reason: As in the first case, there was evidence that Mr. Williams’s victim had abused him and other juveniles.

The judge, M. Teresa Sarmina of the Philadelphia Court of Common Pleas, said prosecutors in Mr. Castille’s office had failed to turn over evidence of the abuse to Mr. Williams’s lawyer, and she vacated the death sentence. That is the ruling Mr. Castille voted to reverse in 2014. In a concurrence, he called Judge Sarmina’s conduct “lawless.”

Last week, Mr. Castille said that Mr. Williams had known the truth but had chosen to lie on the witness stand.

“He was actually a male prostitute,” Mr. Castille said of Mr. Williams. “He was prostituting himself for money. This guy he killed was not the most upstanding individual, but he still took the guy’s life.”

“It’s nothing that was kept from the defense,” Mr. Castille said. “If anything, he kept it from his attorney.”

That is one way to look at it. Here is another, set out in a supporting brief from the American Civil Liberties Union: “Amos Norwood was a middle-aged sexual predator who preyed on teenage boys like Terry Williams,” starting when he was 13. “In exchange for sex, he would give the boys money, food, housing and other gifts.”

“While Williams of course knew of his own past dealings with Norwood and other men,” the brief also said, “it is no surprise that he would not have disclosed such deeply intimate and traumatic events to an attorney he barely knew.”

The vote in the Williams case in 2014 was unanimous, which suggests that the dispute over whether Mr. Castille should have recused himself is academic.

But Mr. Williams’s supporters say he was entitled to an entirely unbiased tribunal, and they point to social science literature demonstrating that group decision making can be powerfully affected by one participant’s strongly held views.

Mr. Castille rejected that line of thinking. “I’ve read the argument that one judge can sway all the other judges,” he said. “That’s not really accurate. The people on our court are all very independent-minded. They might have swayed me. Who knows?”