By treating such terrorists as combatants, however, we accord them a mark of respect and dignify their acts. And we undercut our own efforts against them in the process. Al Qaeda represents no state, nor does it carry out any of a state’s responsibilities for the welfare of its citizens. Labeling its members as combatants elevates its cause and gives Al Qaeda an undeserved status.

If we are to defeat terrorists across the globe, we must do everything possible to deny legitimacy to their aims and means, and gain legitimacy for ourselves. As a result, terrorism should be fought first with information exchanges and law enforcement, then with more effective domestic security measures. Only as a last resort should we call on the military and label such activities “war.” The formula for defeating terrorism is well known and time-proven.

Labeling terrorists as combatants also leads to this paradox: while the deliberate killing of civilians is never permitted in war, it is legal to target a military installation or asset. Thus the attack by Al Qaeda on the destroyer Cole in Yemen in 2000 would be allowed, as well as attacks on command and control centers like the Pentagon. For all these reasons, the more appropriate designation for terrorists is not “unlawful combatant” but the one long used by the United States: criminal.

The second major problem with the approach of the Bush administration is that it endangers our political traditions and our commitment to liberty, and further damages America’s legitimacy in the eyes of others. Almost 50 years ago, at the height of the cold war, the Supreme Court reaffirmed the “deeply rooted and ancient opposition in this country to the extension of military control over civilians.”

A great danger in treating operatives for Al Qaeda as combatants is precisely that its members are not easily distinguished from the population at large. The government wields frightening power when it can designate who is, and who is not, subject to indefinite military detention. The Marri case turned on this issue. Mr. Marri is a legal resident of the United States and a citizen of Qatar; the government contends that he is a sleeper agent of Al Qaeda. For the last four years he has been held as an enemy combatant at the Navy brig in Charleston, S.C.