But Judge Chutkan said on Thursday that she did not want to rely on news reports and wanted the government to disclose such information.
The detainee has raised a dilemma because national security officials believe the man was an Islamic State fighter and do not want to release him, but they lack sufficient evidence to charge him with a terrorism-related crime, officials have said.
At the same time, keeping him in long-term wartime detention without trial as an enemy combatant is seen as unpalatable inside the government, in part because it would give a judge an opportunity to rule that the congressional authorization to fight Al Qaeda does not extend to the Islamic State.
The hearing centered on a habeas corpus lawsuit filed by the American Civil Liberties Union in October on behalf of the man. The rights group is asking Judge Chutkan to order the government to give its lawyers access to the detainee and, more broadly, to declare that his continued indefinite detention without charges is unlawful.
But the Justice Department has argued that the A.C.L.U. has no standing to bring the lawsuit because it has no relationship with him and has not even gained permission from his relatives to represent his interests in court. For that reason, it said, Judge Chutkan lacks jurisdiction and must dismiss the case.
During the hearing, Judge Chutkan, a 2014 appointee of President Barack Obama, signaled discomfort with that position. She accused the Justice Department of employing “circular reasoning” since the government’s own actions have prevented him or his relatives from having contact with the lawyers.
The judge also expressed incredulity that the government, two and a half months into the man’s detention, was still trying to decide what to do with him, asking whether there was any limit to how long officials could take.
“I don’t have an answer,” a Justice Department lawyer, Kathryn Wyer, replied. She said the government was “diligently” working on the problem.
The judge also suggested the government was saying it could “snatch any U.S. citizen off the street and hold him as an enemy combatant in another country” indefinitely without letting him or her talk to a lawyer. She then made her comment about frighteningly unchecked power, and she also portrayed the government as essentially saying, “Just trust us; we know what we’re doing.”
Ms. Wyer pushed back, emphasizing that the government took custody of him on a battlefield. Citing a 2008 case about Guantánamo detainees, she said the Supreme Court had said that the government has a right to take some time to decide what to do with prisoners captured in wartime before they may file habeas petitions.
Jonathan Hafetz, an A.C.L.U. lawyer, told the judge that the case was a “nightmare scenario” and urged her not to dismiss the case, saying that at a minimum she should ask the detainee whether he wanted to file a habeas corpus petition and, if so, wanted the A.C.L.U. to represent him.
But Ms. Wyer argued that Judge Chutkan lacked the authority to carry out even that kind of intervention if the A.C.L.U. had no standing to file the case in the first place.
The court filing suggested that American officials had not raised the issue of a habeas corpus case with the detainee, saying the Justice Department was “not currently aware of any additional information regarding the individual’s wishes in connection with his invocation of constitutional rights or pursuit of remedies in U.S. courts.”