During a nuclear emergency, the government might be tempted to actions that violate or nearly violate our civil liberties traditions. Such actions would create practical precedents affecting future official attitudes; moreover, such actions might be upheld by the courts, creating formal legal precedents as well. And, regardless of what the government does or does not do, a nuclear emergency might create public demands for increased govern-mental powers that could later infringe upon civil liberties. This paper attempts to evaluate these risks to civil liberties.