The chaotic scene involving President Trump testifying at a Lower Manhattan courthouse on Monday  could offer a preview of even weightier appearances to come across his four criminal trials. 

Or it could serve as a warning to defense counsel that the former president is too big a risk to take the stand. That, at least, could be one takeaway from Mr. Trump’s appearance under oath during his fraught civil fraud trial at Manhattan. 

During a combative session, Judge Arthur Engoron told the former president’s lawyers, “I beseech you to control him if you can. If you can’t, I will. I will excuse him and draw every negative inference I can” with respect to assessing penalties against Mr. Trump, his family, and his businesses.

The judge also admonished Mr. Trump: “This is not a political rally. This is a courtroom.” To one of Mr. Trump’s responses, Judge Engoron responded, “Stricken, stricken, stricken,” meaning that it will be excised from the court’s records. Mr. Trump is already laboring under the strictures of a gag order for comments he has made regarding Judge Engoron’s law clerk, Allison Greenfield.

While the circumstances will differ, it’s not hard to imagine that Mr. Trump’s assertion on the stand that “this is a very unfair trial” could be repeated when it comes to the two prosecutions being brought by Special Counsel Jack Smith and one apiece from District Attorneys Fani Willis and Alvin Bragg. What would be the implications of similar behavior there? 

While the former president did not invoke the Fifth Amendment’s protection against self-incrimination in this civil trial, the stakes at a criminal case could persuade Mr. Trump’s attorneys to convince their client to turn taciturn. There, Mr. Trump will have a jury to contend with, too. The fraud case is a bench trial, meaning that Judge Engoron is the sole trier of fact.

A possible contribution to Mr. Trump’s combativeness in Judge Engoron’s courtroom could be that the verdict is already assured. The judge handed prosecutors a victory before the trial even began by ruling in the government’s favor on the key question of whether Mr. Trump, his family, and their businesses engaged in fraud. The jurist found that they had done so.

That ruling means that the trial at which Mr. Trump appeared Monday is dedicated solely to determining penalties. The attorney general has asked that the Trumps and their businesses disgorge $250 million for misleading banks and lenders as to property valuations. Judge Engoron has also ruled that Mr. Trump’s businesses at New York must be dissolved, a ruling that Mr. Trump has appealed. 

At a criminal trial, Mr. Trump will face an inverted state of affairs. He will be accorded the presumption of innocence, and any verdict will have to be brought in by a jury of his peers, not one judge, who will merely preside and determine sentencing in the event of a conviction. 

With a jury as audience and his freedom at stake, Mr. Trump could have far more to lose at his next trials than he does at this one. It is possible, though, that he could conclude that rhetorical fireworks could sway at least one juror to acquit. Unanimity is required to bring in a conviction.

One incentive for Mr. Trump to have taken the stand in this civil case but to stay mum in his criminal ones could derive from the differing law that governs the two genres. In a civil case, a judge is allowed to make a “negative inference” — that’s the phrase Judge Engoron used — from the decision of a party not to testify. Mr. Trump likely felt that he had nothing to lose by speaking. 

In a criminal case, though, the Constitution’s promise that “no person … shall be compelled in any criminal case to be a witness against himself” means that a defendant cannot be penalized for invoking a right vouchsafed by the national parchment, a truth that the judge is tasked with recalling to the jury. Mr. Trump, though, could always — and yet might — choose to waive that privilege and start talking.