US Supreme Court Justice Clarence Thomas, who has not asked a question in court for nearly seven years, has spoken to a lawyer presenting a case.
Justice Thomas, 64, made a comment during a joke about lawyers who studied at Harvard and Yale - both Ivy League universities - lawyers in court said.
He said "Well, he did not...", according to court transcripts, prompting several justices to laugh.
Justice Thomas has not asked a question in court since 22 February 2006.
He has suggested in the past that he holds back from asking questions because he wants to give lawyers a chance to make their case.
He has also said he is self-conscious about the way he speaks, having been teased as a child about the dialect he grew up using in Georgia, and developed the habit of not asking questions at college and law school.
Correspondents say the justice's comments on Monday were not clear, other than that he seemed to be joking about Ivy League law school graduates.
One lawyer said the joke was at the expense of Yale Law School, where Justice Clarence studied, while another lawyer said Harvard Law School was the target of the joke, the Associated Press reported.
The nine-member bench was hearing arguments in the case of Boyer vs Louisiana, in which Jonathan Boyer is seeking to have his murder conviction overturned because he was held in jail for seven years before trial.
His lawyers say Boyer's constitutional right to a speedy trial was violated.
Correspondents say that one issue in the case is whether Boyer's court-appointed lawyers in the early stages of his case were qualified to represent him.
Justice Antonin Scalia asked the lawyer representing the state of Louisiana to confirm which law schools two of the lawyers in question had attended, when Justice Thomas made his comments.
Justice Thomas is the only member of the bench who has a habit of not asking questions when oral arguments are heard by the court.