While the entirety of what Thomas said at 11:45 a.m. wasn't clear, the official transcript caught the words: "Well -- he did not --," The New York Times reported.
Those words broke Thomas' span of official silence while on the bench dating to Feb. 22, 2006, the newspaper noted.
Thomas may have been making a joke when he spoke, the Times said.
The justices were discussing the qualifications of a death penalty defense lawyer in Louisiana when Justice Antonin Scalia said she was a product of Yale Law School, a top school that just happens to also be Thomas' alma mater. During the back-and-forth conversation, Scalia commented about a male graduate of Harvard Law School, Thomas leaned into his microphone and made the remark, which the transcript noted was followed by laughter in the courtroom.
The Times said people in the room at the time understood Thomas to say that a law degree from Yale may actually be proof of incompetence.
While Thomas is known to converse with fellow justices out of microphone range, confirmed comments from the bench are rare. The Times said Thomas has previously indicated he has some self-consciousness about his speech patterns, a carryover from his childhood in rural Georgia. At other times he has said he is quiet out of simple courtesy and also has complained about the difficulty of interjecting among his more talkative colleagues.