Justice Clarence Thomas on Monday broke his 10-year streak of not asking questions during oral arguments, one of the public’s most enduring curiosities about the Supreme Court.

Thomas stunned the courtroom by speaking up during a (relatively) low-profile case involving a federal law that bans people convincted of domestic violence from owning a gun. Thomas asked whether conviction for breaking any other law suspends a person’s constitutional rights.

Thomas stopped Assistant Solicitor General Ilana H. Eisenstein just as she was about to stop presenting her case.

“Ms. Eisenstein, just one question,” Thomas said.

“Can you give me — this is a misdemeanor violation. It suspends a constitutional right. Can you give me another area where a misdemeanor violation suspends a constitutional right?” He then went on to ask a number of follow-up questions.

The content of the Thomas inquiry was of less interest than it having happened at all.

Thomas last asked a question in court Feb. 22, 2006. His participation Monday might have been influenced by the death of his closest ally on the court, Justice Antonin Scalia. Scalia died Feb. 13.

Scalia was one of the court’s most aggressive questioners.

Thomas has given several reasons over the years for not asking questions. He has said that his colleagues ask too many, for instance, and that oral arguments should be a time for lawyers to present their cases....