WHILE THE BUSH administration and the courts have tangled over the perplexing legal problems of the war on terrorism, Congress has remained on the sidelines. This abdication has allowed a whole regime of detention, trial, and interrogation to develop largely without comment or guidance from elected lawmakers, based on age-old precedents in wars completely different from the modern global war on terrorism. Last week, there was an encouraging stirring: a hearing of the Senate Judiciary Committee, at which key members of both parties declared that Congress needs to do more about detentions at Guantanamo Bay, Cuba.

Committee Chairman Arlen Specter (R-Pa.) said that "Congress hasn't acted, and that's really what the focus of our hearing is today as to what ought to be done." Sen. Lindsey O. Graham (R-S.C.) suggested "some general statutory language to help define what's going on at Guantanamo Bay, to better define what an enemy combatant is, to make sure that due process" is being granted. If Congress is serious about getting involved, there is a great deal of work for it to do. The administration should also welcome, not resist, congressional participation. Congress can position the military far better in ongoing litigation in exchange for what should be tolerable restraints on administration conduct.

Three critical steps must be taken by Congress to regularize detentions at Guantanamo -- leaving aside the still more troubling detentions by the CIA entirely outside of the military system. First, authorize in law reasonable procedures for determining who is an enemy combatant and who needs to be detained as time goes on. The administration has moved in the past year to create such review procedures, under which 38 inmates have been determined not to be enemy combatants. Still, serious questions remain about evidence and standards and how open the process should be. Clear legal rules, as Mr. Graham suggests, would be helpful.

Congress should also fix the mess that the military has made of its efforts to try certain detainees for war crimes. More than three years after inmates began arriving at Guantanamo, not a single trial has taken place; most recently, the tribunals, known as commissions, have been stopped by a federal judge. A big part of the problem has been the military's insistence on jettisoning its well-established system of courts-martial and reviving, instead, a system of military justice not attempted since the World War II era. This decision has undermined fairness and produced administrative chaos. More traditional courts-martial at Guantanamo would require adjustments to be practicable -- some of them challenging to civil liberties. It would be far better, however, to work from a known and proven model.

Finally, Congress must establish clearer rules governing interrogation. Some of the tactics the administration has sanctioned are beyond the pale and ought to be banned by law -- and evidence obtained by such means kept out of adjudications of enemy combatant status. As a general principle, interrogation tactics that would violate the Eighth Amendment if engaged in domestically should not be permitted. Detainees at Guantanamo may not have rights under the Constitution, but Congress can and should insist that U.S. actions comport with the rule of law.