The lawyers, who represent “war on terror” suspects, want a US judge to rule against military review tribunals which were set up by the Pentagon to determine whether the prisoners should be designated as “enemy combatants”.
This designation gives them lesser protection under international law.
During a three-hour hearing on Wednesday, the attorneys called the tribunals unfair and inadequate.
“They mock this nation’s commitment to due process,” defence attorney Joseph Margulies.
However, the government’s attorney said US courts should not have jurisdiction over Guantanamo.
“I don’t mean to be off-putting, but the judicial role is very narrow here,” Justice Department attorney Brian Doyle told Judge Joyce Green.
The judge will shortly rule on the government’s motion that the detainees’ petition be dismissed.
US authorities say Guantanamo
Green grilled Doyle over the precise definition of “enemy combatant” during the hearing.
She posed a hypothetical question, asking Doyle whether a “little old lady in Switzerland” giving money to an Afghan orphanage without knowing it was financing al-Qaida could be held as an enemy combatant.
Doyle replied that she may be held as such.
Most of the 550 Taliban and al-Qaida suspects held in Guantanamo were rounded up during military operations in Afghanistan following the September 11 attacks.
The US has consistently labelled them terrorists and a threat to national security. However, it insists the detainees are being well treated.
On the other hand, human-rights groups have branded Guantanamo Bay a concentration camp.
They say hundreds of detainees remain held in tiny cells for up to 24 hours a day without any legal process.
US authorities, they say, are guilty of cruel, inhuman and degrading treatment as well as repatriation of detainees to countries where they are in danger of torture or other serious violations.