"Contrary to the position of the government, the record on review consists of all the information a tribunal is authorized to obtain and consider," the court ruling stated.
The court also ruled that detainees' lawyers should have access to classified information relating to clients' cases. "Certain highly sensitive information" may be withheld from the lawyers, but not from the court, the judges ruled.
Lawyers for the detainees argued in mid-May that being able to review all documents compiled by the U.S. government, not just those presented to the military tribunal, could help them clear the detainees, some of whom have been jailed for more than five years.
There are about 385 detainees at Guantanamo, which was set up to handle prisoners captured by the United States following the September 11 attacks.
U.S. government attorneys have argued that any evidence that could help clear prisoners would have been turned over to the military tribunal that made the "unlawful enemy combatant" determination.
In rejecting that argument, the court ruled that an adequate review of the tribunal's determination cannot be made "without seeing all the evidence, any more than one can tell whether a fraction is more or less than one-half by looking only at the numerator and not at the denominator."
The court also rejected the government's position that lawyers should only have one eight-hour visit to Guantanamo to obtain approval from a prisoner to represent him.
The judges said a second visit would allow the lawyer "time to earn the detainee's trust."
Democrats in Congress are considering legislation calling for closing the Guantanamo prison, arguing indefinite detentions and allegations of prisoner mistreatment, which the military denies, is hurting the United States' reputation abroad and stoking potential acts of terrorism.