The Supreme Court on Tuesday overturned a Louisiana man’s murder conviction in its latest evaluation of whether prosecutors in New Orleans withhold evidence to win convictions.

In an 8 to 1 ruling written by Chief Justice John G. Roberts Jr., the court said prosecutors who worked for former district attorney Harry Connick Sr. should have turned over to defense lawyers statements from one of the survivors of a 1995 shooting rampage that left five dead.

Larry Boatner was the sole witness against Juan Smith, who was convicted of five counts of first-degree murder. But it was not until lawyers were working on Smith’s appeal that they discovered documents in which Boatner initially said he could not identify any of the men involved in the shootings.

Since the court’s 1963 decision in Brady v. Maryland , prosecutors are obligated to turn over evidence that is favorable to the defense and material to the defendant’s guilt or punishment. New Orleans prosecutors argued that the documents were favorable to the defense but would not have changed the jury’s decision.

During oral arguments in November, the justices derided the prosecutors’ case, and Tuesday’s four-page opinion indicated that it had been an easy decision for them.

“Boatner’s testimony was the only evidence linking Smith to the crime,” Roberts wrote. “Boatner’s undisclosed statements were plainly material.”

Justice Clarence Thomas wrote the lone dissent, complaining that the other justices did not look at the complete record of the trial in making their decision.

New Orleans prosecutors said immediately after the court’s decision that they will seek to retry Smith, who has also been convicted of a triple murder and is on death row.

Thomas last year wrote the majority opinion in another case involving Connick, who left office in 2003. In that 5 to 4 decision, the court stripped a $14 million award from John Thompson, who spent 14 years on death row after prosecutors withheld evidence that showed his innocence.

Thomas, joined by the court’s other conservatives, said that Thompson did not meet the high standard of showing a pattern of “deliberate indifference” on Connick’s part.

Justice Ruth Bader Ginsburg, on behalf of the court’s liberals, read her dissent from the bench in that case, saying she would have upheld the award against Connick’s office for the “gross, deliberately indifferent and long-continuing violation of [Thompson’s] fair trial right.”

Smith’s lawyers point out that courts have overturned four death sentences from Orleans Parish because of violations of the Brady rules, and they say eight other non-capital cases have come to the same end.

The case is Smith v. Cain.

In a separate 8 to 1 decision, the court said that consumers who are unhappy about allegedly hidden costs in the credit cards they receive from “credit repair” companies must settle their claims through arbitration.

Justice Antonin Scalia wrote for the court that language in the Credit Repair Organizations Act that says consumers have a “right to sue” is satisfied by the agreement they sign that says disputes will be handed by arbitration.

Ginsburg, the lone dissenter, said that such a reading “may be comprehensible to one trained to ‘think like a lawyer.’ ”

“But Congress enacted the CROA with vulnerable consumers in mind — consumers likely to read the words ‘right to sue’ to mean the right to litigate in court, not the obligation to submit disputes to binding arbitration.”

The case is CompuCredit Corp. v. Greenwood.