ASHINGTON, April 20 — The Supreme Court appeared distinctly unreceptive Tuesday to the Bush administration's argument that the federal courthouse doors must remain closed to the foreign detainees at the Guantánamo Bay naval base in Cuba.

In the first of three cases this month on the right to judicial review of those deemed enemy combatants, most justices seemed to regard the World War II-era precedent that is the cornerstone of the administration's strategy as ambiguous, irrelevant or even counter to the administration's position.

Even Solicitor General Theodore B. Olson's opening declaration, "The United States is at war," appeared to rankle rather than persuade the skeptical justices.

"Supposing the war had ended," Justice John Paul Stevens asked Mr. Olson. "Could you continue to detain these people in Guantánamo, and would there then be jurisdiction?"

Mr. Olson replied, "We believe that there would not be jurisdiction."

Justice Stevens then asked, "So the existence of the war is really irrelevant to the legal issue, is it not?"

True, Mr. Olson acknowledged, the government's position did not depend on the continued military conflict in Afghanistan. "But it's even more forceful and compelling" in that context, he said.

In addition to Justice Stevens, Justices Ruth Bader Ginsburg, David H. Souter, Stephen G. Breyer and Sandra Day O'Connor also appeared unpersuaded by the administration's arguments.

At issue was whether the Guantánamo detainees, some 600 men of varying nationalities seized in Afghanistan and Pakistan during operations against the Taliban, can have access to federal court to contest their detention through petitions for habeas corpus, the ancient writ by which prisoners in the English-speaking world have for centuries been able to challenge the legality of their confinement.

The federal appeals court here ruled last year that the federal courts lack jurisdiction to consider habeas corpus petitions from the detainees at Guantánamo. The two cases the Supreme Court combined for the argument on Tuesday were brought on behalf of 16 detainees, who all maintain that they were innocent noncombatants, some mistakenly picked up by bounty hunters, when they were seized.

While hearing the case on behalf of noncitizens, the justices and most others in the crowded courtroom — some of whom had waited in line since 11 p.m. Monday — also no doubt had in mind the next round in the court's review of the administration's pursuit of its war on terrorism.

Two cases to be argued next Wednesday test the rights of United States citizens, Yaser Esam Hamdi and Jose Padilla, held for two years in military custody on suspicion of collaborating with Al Qaeda but never officially charged or given the opportunity to contest the basis for being designated enemy combatants.

Arriving at the court two and a half years after the Sept. 11 attacks, the three cases present the Supreme Court with a long-anticipated opportunity to examine not only the balance between civil liberties and national security, but between the executive branch and the judiciary as well. Framed as questions of federal court jurisdiction, the cases bring central questions of judicial authority to a court that has been notably jealous of its own prerogatives.

John J. Gibbons, a retired federal judge who argued on behalf of the detainees, emphasized that strand of his argument in his opening words. "What's at stake in this case is the authority of the federal courts to uphold the rule of law," he said.

His argument was not particularly eloquent, but the fact that he was making it lent an air of authority to the detainees' cause. Mr. Gibbons, 79, was named to the federal appeals court in Philadelphia by President Richard M. Nixon. He served as chief judge before retiring in 1990 to join a major law firm in Newark.

As a young Navy officer, Mr. Gibbons spent a year at Guantánamo Bay. One major issue in the case, Rasul v. Bush, No. 03-334, is how to characterize the United States role in that Cuban outpost, which it has occupied since 1903 under a perpetual lease that gives it "complete jurisdiction and control" while preserving Cuba's "ultimate sovereignty."

While the correct interpretation was the subject of vigorous debate on Tuesday, the Supreme Court precedent at the core of the legal argument, a decision from 1950 called Johnson v. Eisentrager, indicated that noncitizen enemy combatants held outside the United States have no right to habeas corpus. So it was important for the detainees to try to show that Guantánamo Bay should be considered functionally, if not formally, part of the United States.

"Guantánamo Navy Base, as I can attest from a year of personal experience, is under complete United States control and has been for a century," Mr. Gibbons said.

Justice Ginsburg said with a smile: "We don't need your personal experience. That's what it says in the treaty. It says `complete jurisdiction, complete jurisdiction and control.' "

Chief Justice William H. Rehnquist objected: "It also says Cuba retains sovereignty."

Mr. Gibbons replied: "Cuban law has never had any application inside that base. A stamp with Fidel Castro's picture on it wouldn't get a letter off the base."

He added: "It's so totally artificial to say that because of this provision in the lease, the executive branch can create a `no law' zone where it is not accountable to any judiciary anywhere."

The Johnson v. Eisentrager precedent also figured heavily in the argument made by Mr. Olson, whose wife, Barbara, died in the Sept. 11 attacks. He contended that the case, which rejected habeas corpus petitions from 21 German civilians who had been caught spying for Japan in wartime China, established a rule barring the federal courts from even considering petitions from enemy aliens being held overseas.

The Guantánamo detainees' lawyers, however, argue that the decision indicates the court did exercise jurisdiction and then rejected the petitions on their merits, at least in part because the Germans had already been tried and found guilty by a military commission. If that interpretation is accepted, then there is no binding Supreme Court precedent that bars jurisdiction in the Guantánamo case for petitioners who have been neither charged nor tried.

Justice O'Connor, whose vote is likely to be crucial, appeared to accept that view. "What it seemed to do was to reach the merits and say at the end of the day, these people have no rights," Justice O'Connor said of the Eisentrager ruling. "They've had a trial under the military tribunal and they have no rights that could be granted," she added.

A Supreme Court decision finding jurisdiction to hear the Guantánamo detainees' habeas corpus petitions would raise — but almost certainly leave to the lower courts to answer — the further question of whether those petitions should be granted.

Justice Breyer suggested that the court could adopt a "protective but practical" standard for evaluating the merits of the petitions.

As he told Mr. Olson, Justice Breyer said: "If we go with you, it has the virtue of clarity. There is a clear rule. Not a citizen, outside the United States, we don't get your foot in the door. But against you is that same fact. It seems rather contrary to an idea of a Constitution with three branches that the executive would be free to do whatever they want, whatever they want without a check."

Justice Breyer continued: "We have the possibility of really helping you with what you're really worried about, which is undue court interference, by shaping the substantive right to deal with all those problems of the military that led you to begin your talk by reminding us of those problems. So if that's the choice, why not say, `Sure, you get your foot in the door, prisoners in Guantánamo,' and we'll use the substantive rights to work out something that's protective but practical?"

Mr. Olson barely had a chance to respond before Justice Antonin Scalia began to make his argument for him. Addressing Mr. Olson, but clearly aiming his rebuttal at Justice Breyer, Justice Scalia said: "We can't call witnesses and see what the real problems are, can we, in creating this new substantive rule that we're going to let the courts create."

He continued: "We have only lawyers before us, we have no witnesses, we have no cross-examination, we have no investigative staff. And we should be the ones, Justice Breyer suggests, to draw up this reticulated system to preserve our military from intervention by the courts?"

The exchange provided one of the few dramatic moments of the argument, indicating that however the court resolves this case, the decision is not likely to be unanimous.