Abstract: A constitutional showdown is a disagreement between branches of government about their constitutional powers that ends in the total or partial acquiescence by one branch in the views of the other and that creates a constitutional precedent. Standard examples of showdowns include disputes over executive privilege, war-making and -funding, and court-packing. Showdowns are costly because they interfere with the normal operation of government, but they also produce important and overlooked benefits. They are an important mechanism of constitutional development, and, among other things, clarify the lines of constitutional authority. We tote up the costs and benefits of constitutional showdowns, show their continuity with other legal phenomena, and criticize the prevailing wisdom that government agents should avoid them as much as possible.