The casual use of the word "war" has lead to a mentality among the public and even in the government that the rules of war could apply to those held at Guantanamo. But the rules of war apply only to those involved in a lawfully declared war, and not to something that the government merely calls a war. Only Congress can declare war— and thus trigger the panoply of the government's military powers that come with that declaration. Among those powers is the ability to use military tribunals to try those who have caused us harm by violating the rules of war.
The last time the government used a military tribunal in this country to try foreigners who violated the rules of war involved Nazi saboteurs during World War II. They came ashore in Amagansett, N.Y., and Ponte Vedra Beach, Fla., and donned civilian clothes, with plans to blow up strategic U.S. targets. They were tried before a military tribunal, and President Franklin D. Roosevelt based his order to do so on the existence of a formal congressional declaration of war against Germany.
In Ex Parte Quirin, the Supreme Court case that eventually upheld the military trial of these Germans—after they had been tried and after six of the eight defendants had been executed—the court declared that a formal declaration of war is the legal prerequisite to the government's use of the tools of war. The federal government adhered to this principle of law from World War II until Bush's understanding of the Constitution animated government policy.
The recent decision to try some of the Guantanamo detainees in federal District Court and some in military courts in Cuba is without a legal or constitutional bright line. All those still detained since 9/11 should be tried in federal courts because without a declaration of war, the Constitution demands no less.