Abstract: This Essay explores some general characteristics of the U.S. response to questions of civil liberties in wartime. After addressing some general challenges to the proposition that during war, law is silent, the Essay sketches the historical pattern, in which wartime actions become regarded as civil liberties violations after the emergency has passed. It argues that this pattern can be explained by a combination of difficulties of decision-making in conditions of uncertainty, with systematic and predictable errors in judgment. The Essay describes a process of social learning, in which the lessons of the past have produced incrementally smaller civil liberties violations over time. It concludes with an analysis of the constitutional status of emergency powers, analyzing the Habeas Corpus Clause and suggesting that attempting to control exercises of emergency power through constitutional provisions is misguided, and that treating such powers as extra-constitutional would contribute more to the process of social learning.