On October 17, 2006, seated in the East Room of the White House, President George W. Bush signed the Military Commissions Act of 2006 (MCA) into law. Moments before, he succinctly—if not entirely accurately—recounted the Act's history:

In the months after 9/11, I authorized a system of military commissions to try foreign terrorists accused of war crimes. . . . [T]he legality of the system I established was challenged in the court, and the Supreme Court ruled that the military commissions needed to be explicitly authorized by the United States Congress . . . I asked Congress for that authority, and they have provided it.

But what exactly did the MCA grant our federal executive authority to do?

At the close of his speech, President Bush claimed that those who had supported the MCA were bequeathing to America a "freer, safer . . . world." But in the weeks preceding the bill's passage, many had vociferously disagreed with the President's characterization of the bill. In editorials and in legal web logs, constitutional scholars were up in arms. Tellingly, complaints came from across the political-ideological spectrum, and at least one cable news anchor went so far as to denounce the MCA as the "[b]eginning of the end of America." There seemed to be much to disagree over. Said one vocal law professor, "Choosing the most indefensible provision of this bill is a tall order—there are many worthy candidates." Still, objections to the bill did coalesce around certain poles. Chief among detractors' concerns were provisions of the MCA appearing to provide the executive with the authority to try American citizens before military commissions or detain them indefinitely...