This week's Supreme Court decision barring the use of military tribunals for terrorism suspects being held at Guantanamo Bay, Cuba, is the latest example of how the U.S. court system can act as a check on the power of both the president and Congress.
In one sense, the Supreme Court ruling was narrowly focused on striking down the Bush administration's planned use of military tribunals, or commissions, to try terrorism suspects being held at Guantanamo.
But many legal experts and some members of Congress believe the high court's decision may have broader implications about the limits of presidential power during wartime.
The legal challenge to the military tribunals was brought by Salim Ahmed Hamdan, who has been charged with conspiracy.
U.S. officials say he used to be Osama bin Laden's driver and bodyguard. Georgetown University law professor Neal Katyal is one of Hamdan's lawyers.
"Some little guy, you know, a fourth-grade education Yemeni, like Mr. Hamdan, can sue the most powerful man in the world and win in our highest court. That is something that is fundamentally great about America and something we should be celebrating to the rest of the world."
A five-member majority of the Supreme Court found that President Bush had exceeded his authority in directing the defense department to set up the military tribunals without authority from Congress.
President Bush says he is willing to work with Congress in writing legislation that would authorize the tribunals in keeping with the Supreme Court decision.
"And we will work with the Congress. I want to find a way forward. In other words, I have told the people that I would like for there to be a way to return people from Guantanamo to their home countries. But some of them need to be tried in our courts."
Three of the Supreme Court justices dissented in the case. One of them, Justice Clarence Thomas, argued that denying the administration the right to try detainees through military tribunals would hamper the president's ability to fight the war on terror.
Some conservative activists agree, including Richard Samp of the Washington Legal Foundation.
The American people ought to be rebuking the Supreme Court for ignoring the will of the elected branches of government.
Republicans and some Democrats have indicated a willingness to work with the White House to craft a law authorizing the use of military tribunals.
But some Democrats also see the Supreme Court decision as a constitutional check on an administration that has assumed broad powers since the 2001 terrorist attacks on the United States.
This is Democratic Senator Richard Durbin of Illinois.
"The administration claimed that it could act as legislative, judicial and executive when it came to the treatment of these prisoners. Today, the Constitution prevailed."
Some Democrats and some legal analysts believe the high court's rebuke on the detainees could have implications for the Bush administration's decision to monitor international phone calls of suspected terrorists without a court warrant.
That program is run by the National Security Agency, and has come under fire from many Democrats and civil liberties activists as an abuse of presidential power.
Bush administration officials tend to see the Supreme Court ruling as narrowly focused on the issue of the military tribunals, and are not interpreting the decision as a broad check on the president's authority.
This is White House spokesman Tony Snow.
"It has not said you can't hold them. It hasn't said you can't try them. It hasn't said you have to send them back. So, what you do have are matters of procedure, and, no, I don't think it weakens the president's hand."
Other analysts believe the court's ruling has sent a strong message about the checks and balances and separation of powers that are an essential part of American democracy.
Attorney Sidney Rosdeitcher has argued cases before the Supreme Court, and has worked on international human rights issues for the New York City Bar Association.
"Let us hope that this heralds a new day, in which what the United States has always stood for, which is the rule of law and due process, is now underscored for the Bush administration, but more importantly, for the entire world and for the American people."
The Supreme Court decision on the military tribunals was the second major legal setback for the administration on its handling of suspected terrorists.
Two years ago, the high court ruled that the prisoners at Guantanamo were entitled to access to U.S. civilian courts, over the objections of the administration.
