"The laws and constitution are designed to survive, and remain in force, in extraordinary times," the court said in its historic ruling, for the third time in four years striking down the government's case for trying "war on terror" suspects in military tribunals.
White House spokeswoman Dana Perino said the administration was "reviewing the opinion" but declined immediate comment.
Thursday's ruling should now give the prisoners and their legal teams the right to demand to know on what basis they are being held.
It was not immediately clear how Thursday's ruling would affect those 270 detainees still held in the jail. Amnesty International said the decision was an "essential step forward towards the restoration of the rule of law."
Now I challenge all our esteem Judges to do the right thing with our ISA. Are you guys just another high class pen pushing civil servants or leaders of time, dare to be different and bring our system in line with international standards.