In a “show trial” like this one with intense security measures and a plethora of witnesses, Mr. Cutler said the defense has to mount a show of their own.

“Trials like this are never won, unless — unless — you do something unusual,” he said.

Mr. Guzmán might not have much to lose. In nearly three months of testimony, prosecutors have used Mr. Guzmán’s former associates, law enforcement officials and secretly recorded phone calls and text messages to exhaustively paint him as a vindictive, murderous criminal who led the largest drug trafficking organization in North America.

“He may feel that it’s a foregone conclusion that he will be convicted,” said Bruce Green, a professor at Fordham Law School who specializes in legal ethics and criminal procedure. “And the testimony that he wants to give may not be to get the jury to acquit him but rather to establish his place in history and to explain himself to the world.”

Preparing Mr. Guzmán for the stand would take time, and Mr. Balarezo said such preparation had not yet begun.

“Any client who testifies obviously has to be advised of the possible consequences of testifying,” Mr. Balarezo said. “And has to be prepared to face cross-examination.”

Mr. Guzmán’s possible testimony could come soon. Prosecutors told the judge earlier this week they expect to rest their case by Jan. 28 at the latest. Afterward, the defense will mount its own case.

Mr. Guzmán’s testimony, if it happens, would be likely to extend the trial by a week or more since he’d have many details to offer and the cross-examination would probably be lengthy.