GUANTÁNAMO BAY, Cuba - The first indication that the afternoon’s hearing in the case of Salim Hamdan was going to be different came when he showed up in war crimes court in his prison khakis, a loose-fitting outfit that looked like yesterday’s pajamas.

The flowing white robe and the checked blazer he wore in Tuesday morning were gone. A curious prosecutor asked the judge to inquire. The judge, a Navy captain with something of a soft touch, said Mr. Hamdan could wear whatever he wanted to court.

For a minute, the routine of legal arguments resumed in the courtroom on the hill overlooking the old Guantánamo airstrip.

But then, in that complicated dance that comes when a man has a translator, there was a stir at the defense table and some signaling. Mr. Hamdan had something to say. “I like this clothes,” he said.

Then, Mr. Hamdan, whose name already has a big place in American law, and the Navy judge, who seemed to want most to keep his case moving, began an extraordinary 40-minute exchange about the fairness of Guantánamo and the definition of justice.

“There is no such thing as justice here,” Mr. Hamdan said. He said he would boycott. He said he would not allow his lawyers to speak in his absence, an option it is not clear he has.

Before long there was a good-natured debate, tinged with a little desperation on both sides, and amiable apologies from Mr. Hamdan. It was soon obvious that the back-and-forth was leading toward the latest bewildering wrench in the military tribunal system here. Can a detainee tie the system in knots by saying he is boycotting but keeping his lawyers to muzzle them?

Mr. Hamdan is one of Guantánamo’s most famous detainees. A 2006 United States Supreme Court ruling that bears his name ended the Bush administration’s first system of trying to bring detainees to trial here.

On Tuesday, he became an ambassador of sorts for frustrated detainees, whose lawyers have told them about cases in their names that never seem to mean much in the parched detention camps. He mentioned his own case, and one in the name of another detainee, Lakhdar Boumediene, which the Supreme Court is now considering.

He said he had learned a little English in more than six years here. It seemed he had learned a little law, too.

He noted that the court was not applying United States law, but some new law that he said seemed to have been passed just for him, since it followed his Supreme Court victory.

The Military Commissions Act, passed by Congress in 2006, governs the court here, the judge, Capt. Keith J. Allred, acknowledged.

“They changed the law,” Mr. Hamdan said. “Why did they change the law? Just for my case?”

At every court session here, Judge Allred, a square-jawed, deliberate man, seems to spend an extra instant as he passes Mr. Hamdan’s table to lock eyes with him.

Looking down across the makeshift courtroom on Tuesday, Judge Allred told Mr. Hamdan he wanted to give him a fair trial. He coaxed his famous defendant, who was once Osama bin Laden’s driver, to stick with the process.

“Mr. Hamdan,” Judge Allred said, “I think you should have great faith in American law. You have already been to the Supreme Court.”

“The Supreme Court of the United States,” he continued, “said to the president, ‘You can’t do that to Mr. Hamdan.’ You were the winner. Your name is printed in our law books.”

The detainee, a handsome man with curly brown hair and a quick grin, was noncommittal. Mr. Hamdan, in his seventh year of captivity, noted that despite the judge’s literal words, he had not been to the Supreme Court himself. The lawyers, he said, had not taken him with them.

The detainee and the judge shared a laugh.

It was not the first time the two had talked across the well of the courtroom as startled lawyers on both sides looked on helplessly. At times, it seemed as if they were friends.

Judge Allred, reassuringly: “I appreciate your frustration.”

Mr. Hamdan, with a shrug: “I am not making fun of you; it’s just the way I speak, my style.”

The judge explained that Mr. Hamdan might do better with the military jurors if, instead of an empty chair, they saw a smiling defendant. “They may learn to like you,” he said.

Mr. Hamdan said, “I’m sorry.” Then his chair was empty.

© 2008 The New York Times