Israeli Prime Minister Benjamin Netanyahu's visit to Washington has provoked a broad debate over the military and political wisdom of an attack on Iran. But so far, there has been little attention to the legal issues involved, which are crucial. American support for a preemptive strike would be a violation of both international law and the U.S. Constitution.
Article II of the Constitution requires the president to "take care that the laws be faithfully executed," and Article VI says that treaties are part of the "supreme law of the land." Since the Senate overwhelmingly ratified the United Nations Charter as a treaty in 1945, the president is constitutionally required to abide by Article 51 of the charter. This provision allows states to use military force in self-defense only when respon