When President Bush authorized the use of military tribunals last fall to bring suspected terrorists to justice, he emphasized that such harsh tactics would not be used against US citizens.
This week, that distinction may have been lost in the administration's apparent zeal to safeguard the nation from what once were unthinkable acts of terror.
Both the laws of war and a 1942 Supreme Court precedent "establish that the military may detain a United States citizen who has joined the enemy and has entered our country to carry out hostile acts," Attorney General John Ashcroft says.
But the indefinite detention of Jose Padilla, the suspected "dirty bomb" conspirator, who is a US citizen and has also gone by the name Abdullah al-Muhajir, raises constitutional questions that some experts say could undermine, rather than bolster, the administration's legal war on terrorism.
Chief among the constitutional questions: Who decides who qualifies as "an enemy combatant"? What level of belligerence is necessary to trigger "enemy combatant" status? Would speaking in support of Al Qaeda and critically of the Bush administration in a monitored telephone call, for instance, render a US citizen vulnerable to summary arrest and indefinite detention?
What about financial contributions to an Islamic charity suspected by the administration of being an Al Qaeda front?
"The president is asserting the power to take people into custody on US soil outside the judicial process," says Tim Lynch, director of the project on criminal justice at the Cato Institute in Washington. "We have a Fourth Amendment, and the president seems to be saying he can set that aside and take into custody anybody he or the FBI thinks are involved in terrorism."
Administration officials and supporters maintain that the US is at war with a group of terrorists who are intent on killing as many Americans as possible. Tough measures are necessary to detect and prevent future attacks, they say.
Others counter that the president's powers as commander in chief may be broad, but they are not without limit under the Constitution. Some critics warn that the administration may jeopardize future terrorist trials through what they see as heavy-handed tactics now being employed by US authorities.
If federal appeals courts and eventually the US Supreme Court exert jurisdiction over terror suspects and take a different view of the constitutional requirements in such cases, the resulting decisions could force the dismissal of charges and the quashing of potential evidence and testimony, experts say.
At least one other suspected Al Qaeda supporter who is a US citizen is being held indefinitely, without formal charges. Yasser Esam Hamdi is in a Navy brig in Norfolk, Va. He is seeking access to legal counsel, a move the administration opposes.
"They are trying to carve out some kind of quasi-legal status, not giving [US citizens who are suspected Al Qaeda supporters] the benefit of the US Constitution," says Francis Boyle, an international law professor at the University of Illinois College of Law at Champaign. He says the Padilla case sets up an unusual situation in which Zacarias Moussaoui, a foreign national standing trial in federal court in Alexandria, Va., for alleged involvement in the Sept. 11 attacks, is being accorded the full protections of the US Constitution, while Mr. Padilla, a US citizen, is stripped of many of his constitutional rights.
"The United States has a legal system of which we are proud, but it has resulted in horrible miscarriages of justice in the past," says Alfred Rubin, an international law professor at the Fletcher School of Law and Diplomacy at Tufts University in Medford, Mass. "I don't know what the authority is for the federal government to hold anybody without trial."
The 1942 Supreme Court precedent cited by the administration relates to the case of eight Nazi saboteurs who were tried and convicted by a secret military commission convened in Washington. Six of the saboteurs, including a US citizen of German heritage, were executed.
The Supreme Court upheld the trial and executions, establishing the precedent on which the Bush administration relies.
But not everyone is convinced that the case, called Ex Parte Quirin, stands on firm judicial ground. A Congressional Research Service analysis of the Quirin decision completed in late March quoted two of the justices who participated in the case as expressing reservations about the court's actions.
Justice Felix Frankfurter wrote in 1953 that "the Quirin experience was not a happy precedent." And Justice William Douglas in a 1962 interview said: "The experience with Ex Parte Quirin indicated, I think, to all of us that it is extremely undesirable to announce a decision on the merits without an opinion accompanying it. Because once the search for the grounds, the examination of the grounds that had been advanced is made, sometimes those grounds crumble."