The Supreme Court (search) delivered a mixed verdict Monday on the Bush administration's anti-terrorism policies, ruling that the U.S. government has the power to hold American citizens and foreign nationals without charges or trial, but that detainees can challenge their treatment in U.S. courts.

The administration had sought a more clear-cut endorsement of its policies than it got. The White House claimed broad authority to seize and hold potential terrorists or their protectors for as long as the president saw fit - and without interference from judges or lawyers.

In both cases, the ruling was 6-3, although the lineup of justices was different in the two decisions.

Ruling in the case of American-born detainee Yaser Esam Hamdi, Justice Sandra Day O'Connor (search) said the court has "made clear that a state of war is not a blank check for the president when it comes to the rights of the nation's citizens."

Congress did give the president authority to hold Hamdi, a four-justice plurality of the court said, but that does not cancel out the basic right to a day in court.

The court ruled similarly in the case of about 600 foreign-born men held indefinitely at a U.S. Navy prison at Guantanamo Bay (search), Cuba. The men can use American courts to contest their captivity and treatment, the high court said.

Steven R. Shapiro, legal director of the ACLU, called the rulings "a strong repudiation of the administration's argument that its actions in the war on terrorism are beyond the rule of law and unreviewable by American courts."

The court sidestepped a third major terrorism case, ruling that a lawsuit filed on behalf of detainee Jose Padilla improperly named Defense Secretary Donald H. Rumsfeld instead of the much lower-level military officer in charge of the Navy brig in South Carolina where Padilla has been held for more than two years.

Padilla must refile a lawsuit challenging his detention in a lower court.

The court left hard questions unanswered in all three cases.

The administration had fought any suggestion that Hamdi or another U.S.-born terrorism suspect could go to court, saying that such a legal fight posed a threat to the president's power to wage war as he sees fit.

"We have no reason to doubt that courts, faced with these sensitive matters, will pay proper heed both to the matters of national security that might arise in an individual case and to the constitutional limitations safeguarding essential liberties that remain vibrant even in times of security concerns," Justice Sandra Day O'Connor wrote in the Hamdi case.

O'Connor said that Hamdi "unquestionably has the right to access to counsel."

The court threw out a lower court ruling that supported the government's position fully, and Hamdi's case now returns to a lower court.

O'Connor was joined by Chief Justice William H. Rehnquist and Justices Anthony M. Kennedy and Stephen Breyer in her view that Congress had authorized detentions such as Hamdi's in what she called very limited circumstances,

Congress voted shortly after the Sept. 11 attacks to give the president significant authority to pursue terrorists, but Hamdi's lawyers said that authority did not extend to the indefinite detention of an American citizen without charges or trial.

Two other justices, David H. Souter and Ruth Bader Ginsburg, would have gone further and declared Hamdi's detention improper. Still, they joined O'Connor and the others to say that Hamdi, and by extension others who may be in his position, are entitled to their day in court.

Hamdi and Padilla are in military custody at a Navy brig in South Carolina. They have been interrogated repeatedly without lawyers present.

In the Guantanamo case, the court said the Cuban base is not beyond the reach of American courts even though it is outside the country. Lawyers for the detainees there had said to rule otherwise would be to declare the Cuban base a legal no-man's land.

The high court's ruling applies only to Guantanamo detainees, although the United States holds foreign prisoners elsewhere.

The Bush administration contends that as "enemy combatants," the men are not entitled to the usual rights of prisoners of war set out in the Geneva Conventions. Enemy combatants are also outside the constitutional protections for ordinary criminal suspects, the government has claimed.

The administration argued that the president alone has authority to order their detention, and that courts have no business second-guessing that decision.

The case has additional resonance because of recent revelations that U.S. soldiers abused Iraqi prisoners and used harsh interrogation methods at a prison outside Baghdad. For some critics of the administration's security measures, the pictures of abuse at Abu Ghraib prison illustrated what might go wrong if the military and White House have unchecked authority over prisoners.

At oral arguments in the Padilla case in April, an administration lawyer assured the court that Americans abide by international treaties against torture, and that the president or the military would not allow even mild torture as a means to get information.