In July 1996, the International Court of Justice (ICJ) issued a controversial Advisory Opinion on the legality of nuclear use (including, threat of use). The ICJ found that ‘nuclear use would generally be contrary to the rules of international law’, but it failed to conclude that nuclear use would be unlawful in all circumstances. The major reason for this was because it recognized nuclear norms (that is, the practice of deterrence) to which many states adhered. Taking the American case, this article examines norms of nuclear non-use and nuclear targeting. It shows where these national norms came from, and how they came to be empowered in US policy and embodied in American practice. It is critical of the ICJ's conclusion because, while the norm of non-use is consistent with international law, it finds American targeting norms to be contrary to humanitarian law.