Several years after Keith Tharpe was sentenced to death for murder in 1991, a juror in his case signed an affidavit stating that there are two types of black people: good ones and “niggers.” The juror, who was white, put the defendant in the latter category and said that he wondered “if black people even have souls.”

Mr. Tharpe sits on death row in Georgia. Although his lawyers assert that his punishment was tainted by juror racism, a state court ruled against Mr. Tharpe on that issue two decades ago.

Since then, state and federal courts have put procedural obstacles in front of his efforts to appeal that ruling. Mr. Tharpe seemed to be doomed when the Court of Appeals for the 11th Circuit rebuffed him. He was set to be executed in September 2017.

But the Supreme Court issued a last-minute stay, shaken by the juror’s disturbing affidavit which, in the court’s words, presented “a strong factual basis" that Mr. Tharpe’s race affected the juror’s vote for a death verdict.