But the Pentagon said existing laws allow the indefinite detention of people the US has deemed enemies in the war on terrorism, and that legislation could be too restrictive and was not needed.
"The truth is due to no one's fault Guantanamo Bay is a legal mess," Senator Lindsey Graham, a South Carolina Republican, said at a Senate Armed Services subcommittee hearing on Thursday.
With the Pentagon under fire for the treatment of detainees at Guantanamo, Graham is working on legislation with fellow Republicans John Warner of Virginia, the Armed Services Committee chairman, and John McCain of Arizona to clarify the legal standing of people the administration calls "enemy
combatants" who can be held indefinitely.
Graham pressed a panel of Pentagon legal officials on whether a law passed by Congress clarifying the status of enemy combatants would speed up the legal dispute that has blocked prosecutions of detainees.
Daniel Dell'Orto, the Pentagon's principal deputy general counsel, said the litigation would continue with or without legislation. "I don't know that that's a panacea for any problem we have right now," he said.
The US Supreme Court in June 2004 ruled that detainees had the right to go to federal courts to seek their release from Guantanamo, but there have been sometimes contradictory lower court rulings since then.
The Pentagon is in charge of
prosecuting the detainees
Senators said harsh interrogation practices and the refusal to grant prisoner of war status to detainees could backfire when US soldiers are captured.
"Our troops are looking at us to see whether we're going to adopt a standard that if they were captured would be acceptable," said Senator Carl Levin of Michigan, the committee's top Democrat.
Warner defended Guantanamo's current operations "as the best they can do under a framework of laws that is either not clear or needs to be refined."
Human rights groups and a number of European countries have said that term has no standing under international law, and the detainees should have the rights of prisoners of war.
Guantanamo, opened after the 11 September 2001 attacks, has become a lightening rod for criticism with accusation that the mostly Muslim detainees from the US led offensive in Afghanistan have been tortured and humiliated.
There are about 520 detainees at Guantanamo from more than 40 countries.