International Law, U.S. War Powers, and the Global War on Terrorism

In Congressional Authorization and the War on Terrorism, Curtis Bradley and Jack Goldsmith provide a useful framework for interpreting the contours of the 2001 Authorization to Use Military Force (AUMF). As Bradley and Goldsmith point out, the AUMF is a broad, general authorization to wage war against certain states, organizations, and individuals. And because the AUMF authorizes the President to wage war, it also implicitly authorizes the President to exercise any powers incident to waging war. The most obvious feature of the AUMF, though, is its non-obvious boundaries. What powers are incident to waging war? When, where, and against whom may they be exercised? The central question is how best to interpret the AUMF and, more specifically, how best to define the outer limits, if any, of what Congress authorized the President to do. Bradley and Goldsmith argue that the law of armed conflict (LOAC) informs the proper interpretation of the AUMF. In other words, the AUMF arguably authorizes the President to do what LOAC permits - because, in part, this well established, widely endorsed body of law defines the rights and obligations of belligerents. Despite the substantial virtues of the Article, however, Bradley and Goldsmith systematically understate the interpretive significance of LOAC - and, thereby blunt the sharp edge of several important law-of-war constraints on executive power. In this short essay, we identify two important deficiencies in their framework. First, Bradley and Goldsmith overstate the ambiguity of several relevant principles of LOAC. This ostensible ambiguity threatens to unravel many of the would-be constraints they identify because, as they also point out, the President enjoys substantial discretion to interpret international law. Second, they misspecify the range of LOAC rules that are conditions of the exercise of core war powers (such as the power to detain enemy combatants and the power to prosecute war criminals). We conclude that LOAC should assume a more central role in the interpretation of the AUMF. This body of law, properly understood, suggests several meaningful, strategically viable constraints on executive action in the Global War on Terrorism.