Vanderbilt Law Review


Joshua D. Foote

First Page



At 9:02 a.m. on September 11, 2001, the world watched in horror as American Airlines Flight 175 slammed into the South Tower of the World Trade Center on live television,' ending all consideration that the first collision might have been an accident. Halfway around the world, Ali al Bahlul sat in a remote part of Afghanistan operating a radio so that Usama Bin Laden could monitor reports of the attacks. That day, Al Qaeda terrorists killed 2,977 people, caused billions of dollars of economic damage, and initiated the defining sociopolitical issue of the early 21st century.

Legal practitioners have faced the difficult question of how best to hold terrorists such as Bahlul accountable while remaining true to fundamental constitutional principles and established law. After September 11, the United States quickly established military commissions to prosecute captured terrorists for violations of the law of war, but it did so in an ad hoc manner with little statutory authorization. The need for a more robust body of law to ensure consistency and fairness soon became apparent. Thus, Congress passed the Military Commissions Act ("MCA") in 2006 to define charges and establish a comprehensive framework for the prosecution of alleged terrorists and others accused of committing war crimes in the course of hostilities against the United States. Among the crimes the MCA defined were terrorism, hijacking an aircraft, destruction of property in violation of the law of war, attacking civilians, attacking civilian property, and conspiracy to commit those offenses.

Those charged under the MCA soon challenged its constitutionality, as well as the constitutionality of the commissions system more generally. A prominent contention was that the MCA retroactively permitted prosecution for some crimes in violation of the Ex Post Facto Clause of the Constitution,10 which prohibits retroactive criminalization of previously innocent acts. Most of those charged in commissions faced trial for acts they had allegedly committed before the MCA was written. They claimed that their actions were not criminalized under domestic or international law at the time they allegedly undertook them. By retroactively applying the MCA, they contended, Congress had created a paradigmatic example of the type of ex post facto law prohibited by Article I of the Constitution.