WASHINGTON — For the first 55 minutes of a Supreme Court argument on Wednesday about racial discrimination in jury selection, the justices seemed united in their view that a white Mississippi prosecutor had violated the Constitution in his determined efforts to exclude black jurors from the six trials of Curtis Flowers, who was convicted of murdering four people in a furniture store.

As Mr. Flowers’s lawyer concluded her argument, Justice Clarence Thomas asked his first questions from the bench since 2016. He wanted to know whether the defense lawyer in the sixth trial had excluded any jurors. The lawyer said yes.

“And what was the race of the jurors struck there?” Justice Thomas asked.

White, said the lawyer, Sheri Lynn Johnson.

Justice Thomas holds the modern record for silence on the bench. Before his questions in 2016, he had gone a decade without asking one. His explanations have varied, but he has said lately that the other justices asked so many questions that they were rude to the lawyers before them.