Whatever criticism he has faced does not seem to have fazed Judge Ellis at all in his conduct of Mr. Manafort’s trial, the first to consider charges stemming from the investigation led by Robert S. Mueller III, the special counsel.

“I am a Caesar in my own Rome,” he said at one point, discussing why he refused to allow defendants to plead no contest instead of guilty. “It’s a pretty small Rome,” he added.

Some lawyers who have been in his courtroom say it’s better to allow him to have the last word rather than engage in what are essentially contests over who has more intellectual firepower.

Away from the courthouse, lawyers and former clerks said, there is a softer side to the judge not always visible from the bench. The first judge to preside over a naturalization ceremony in Arlington Cemetery, Judge Ellis is known for growing emotional every time he administers the oath of citizenship.

To the jurors, the judge could not be more solicitous, joking about the plain lunch menu (“You won’t find baked alaska”). At least the meal is free, he told the jurors on opening day, saying he hoped no one had a fleeting urge to “slit their wrists” because they had been unfortunate enough to be picked from the jury pool.

He has clearly reveled in his captive audience. “My hearing is not what it once was,” he said last week, pausing for a beat with comic effect. “Nothing is what it once was.” Born in Bogotá, Colombia, he took the opportunity during a sentencing to display his fluency in Spanish, questioning the defendant himself while an interpreter stood by.

Even if the spectators had come only for the Manafort case, he said, he was glad they got a chance to see the criminal justice system at work. He has weighed in on a variety of issues outside the courtroom, criticizing conditions at a Virginia prison and questioning whether sentencing laws are too harsh.