"No state power is more fearsome than the power to imprison. Hence the habeas right has been at the heart of the centuries-long struggle to constrain governments, a struggle in which the greatest event was the writing of America's Constitution, which limits Congress's power to revoke habeas corpus to periods of rebellion or invasion. Is it, as McCain suggests, indefensible to conclude that Congress exceeded its authority when, with the Military Commissions Act (2006), it withdrew any federal court jurisdiction over the detainees' habeas claims?
As the conservative and libertarian Cato Institute argued in its amicus brief in support of the petitioning detainees, habeas, in the context of U.S. constitutional law, "is a separation of powers principle" involving the judicial and executive branches. The latter cannot be the only judge of its own judgment," - George F Will.