The President and Nuclear Weapons: Authorities, Limits, and Process

There is no more consequential decision for a president than ordering a nuclear strike. The U.S. government grappled with the process for making that decision during the decades of the Cold War. The threat of sudden nuclear annihilation by the Soviet Union shaped the resulting procedures, which emphasize speed and efficiency and which place sole decision-making authority in the president’s hands. Today we face a different threat environment, but tensions remain between states with nuclear weapons. As a result, public and congressional attention has focused on the legal authorities and limitations, as well as the process, that a U.S. president would confront when making the grave decision of whether to use a nuclear weapon. It is a complex subject, and few sources address it clearly and simply. This paper seeks to fill that gap by identifying the key legal questions relevant to a president’s decision and by summarizing the state of the law and the relevant process.

Currently, neither domestic nor international law specifically addresses the authority to use nuclear weapons. Nonetheless, because of the devastating potential of those weapons, existing authorities relating to use of force generally may apply differently to nuclear weapons than to other weapons. The paper looks first at U.S. domestic law, including the Constitution and statutes, and examines the respective powers of the president and Congress in decisions about the use of nuclear weapons. The Constitution’s division of war powers between the executive and legislative branches is notoriously murky. Congressional authority might act in two ways to restrict a president’s decision to use nuclear weapons: (1) if the president is required to seek congressional authorization before use, and (2) if a statute prohibits or limits certain uses of those weapons. Regarding the first, there is little question that a president has the authority to respond in self-defense against a nuclear attack without seeking prior authorization. The more difficult question arises when a president plans a first use of nuclear weapons. There is a strong argument that if a president contemplates a first use of nuclear weapons to preempt a perceived nuclear threat before the threat has developed to the point at which an attack has begun or is imminent, he must first seek authorization from Congress. The legal conclusion might be different, however, if the first use is in response to a conventional attack on the United States or in the course of a conventional armed conflict.