In short, the bill asserts the president's power to snatch anyone from anywhere, including a U.S. citizen on U.S. soil, and confine him in a military prison without charge until the end of a perpetual, worldwide war against an amorphous enemy. Senators from both parties who were alarmed at that prospect tried to remove the detention provisions, but the most they could achieve was an amendment saying the bill does not "limit or expand" the president's powers under the AUMF or "affect existing law or authorities" regarding detention of people "captured or arrested in the United States."
According to its sponsor, Sen. Dianne Feinstein, D-Calif., the amendment was intended to "declare a truce" between those who say the detention power described by Graham already exists and those who disagree. Feinstein said the amendment "leaves it to the courts to decide."
So far the government has not been eager to test the constitutionality of its detention policies. In 2004, the Supreme Court said due process required that a U.S. citizen captured on the battlefield in Afghanistan and held as an enemy combatant be given "a meaningful opportunity to contest the factual basis for that detention before a neutral decisionmaker." The Bush administration let him go instead. In the two cases where the Pentagon took charge of terrorism suspects arrested in the United States, the government likewise avoided a definitive judicial resolution, transferring them back to civilian custody before the Supreme Court had a chance to rule on their treatment.
In any case, the Feinstein amendment (which passed almost unanimously) represents an astonishing abdication of legislative responsibility. The courts should be deciding the constitutionality of the detention policy established by Congress, not sifting through deliberately ambiguous statutory language to figure out what that policy is.