WASHINGTON - His wartime powers undercut once before by the Supreme Court, President Bush could take a second hit in a case in which Osama bin Laden's former driver is seeking to head off a trial before military officers.

At stake is more than whether Salim Ahmed Hamdan, after nearly four years at the Navy prison in Guantanamo Bay, Cuba, goes on trial for war crimes before a special military commission.

Analysts say if the high court rejects Bush's plan to hold such trials for the first time since the aftermath of World War II, it could rein in the president's expanded powers in pursuing and punishing suspected terrorists.

In addition to special military trials for Hamdan and others, the Bush administration since the attacks of Sept. 11, 2001, has claimed it has the authority to eavesdrop on telephone conversations without court oversight, aggressively interrogate foreigners and imprison people without giving them traditional legal rights.

Hamdan was one of hundreds of people captured during the 2001 U.S.-led war that drove the ruling Taliban from power in Afghanistan. The native of Yemen denies that he is a terrorist and claims he took the driving job to provide for his young family.

Hamdan's appeal, set for arguments Tuesday, is one of the biggest cases of the court's current term, the first for Chief Justice John Roberts. He, however, will not participate in the Hamdan case. Last year, Roberts was on a three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit that ruled unanimously against Hamdan.

It is that ruling that the Supreme Court now is reviewing.

With Roberts withdrawing from the case, the high court could split 4-4, leaving the appeals court ruling in place. A ruling is expected before July.

"The stakes are very high for this administration because it has predicated all of its policies in this war on terror on the principle that the president as commander in chief cannot be constrained by Congress or the courts," said Scott Silliman, a former military lawyer who teaches at Duke University.

"If the court in any way limits presidential authority with regard to military commissions, it will spill over into other areas of his authority in this new type of war," Silliman said.

A second element of Bush's terrorism-fighting measures is under scrutiny as the Senate Judiciary Committee on Wednesday examines the president's domestic eavesdropping program, which The New York Times disclosed in December.

Since shortly after the attacks of Sept. 11, 2001, the National Security Agency has monitored the international communications of people inside the United States when their calls and e-mails are believed to be linked to al-Qaida. The government normally has to get a court order to monitor domestic communications; Bush signed an executive order directing the NSA to conduct the operations without a judge's approval.

Hamdan may find hope for his appeal from a pair of 2004 rulings in which the justices rejected the president's claim of authority to seize and detain terrorism suspects while indefinitely deny access to courts or lawyers.

Justice Sandra Day O'Connor wrote at the time that "a state of war is not a blank check for the president when it comes to the rights of the nation's citizens."

The moderate O'Connor has been replaced by a Bush appointee, Samuel Alito, who could play a prominent role in the Hamdan case. As a former Reagan administration lawyer he could be sympathetic to White House arguments.

Hamdan is one of about 490 prisoners being held at Guantanamo Bay as what the administration terms as enemy combatants. Only 10 of them have been charged with a crime.

The administration had kept secret the identities, home countries and other information about the men, who were accused of having links to the Taliban or al-Qaida. But this month the Pentagon released details after losing a lawsuit filing by The Associated Press under the Freedom of Information Act.

The importance of the Hamdan case is illustrated by the dozens of filings on both sides.

The issues it raises are complex, with claims based on the Constitution, federal laws and treaties.

The administration hopes to get Hamdan's appeal dismissed altogether, on grounds that Congress last year stripped the Supreme Court's authority to consider it. A law passed late last year bars Guantanamo prisoners from filing petitions to fight their detentions; the administration claims this law retroactively voided hundreds of lawsuits.

Hamdan's lawyers dispute the government's claim that the law is retroactive and they say the administration has set up a sham system to try Hamdan on a charge of conspiracy to commit war crimes, murder and terrorism.

"The president's assertion of absolute dominion over human subjects and trial and punishment cannot be reconciled" with the Constitution, lead lawyer Neal Katyal, a Georgetown law professor, told justices in a filing this month.

Accused terrorists can receive the death penalty in the military trials, although the government says it is not seeking that against Hamdan.

In his filings, the administration's Supreme Court lawyer, Paul Clement, cites the "savage attacks" of Sept. 11 and the president's response. Clement portrays Hamdan as a trained terrorist who served as a personal bodyguard to bin Laden.

The justices said they will release an audio of the argument after it concludes, something done only for high-profile cases.

The case is Hamdan v. Rumsfeld, 05-184.

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On the Net:

Supreme Court: http://www.supremecourtus.gov/

Military tribunals: http://www.defenselink.mil/news/commissions.html

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