Packing the Courts: Ideological Proximity and Expansions to the Federal Judiciary from 1937 to 2012

What explains expansions to the federal judiciary? Whereas existing research focuses on unified government as an explanation, we argue ideological proximity between institutions involved in the expansion process more accurately predicts judicial expansions. We examine whether Congress chose to add seats to each federal district or circuit court annually from 1937 to 2012 and find expansions are more likely when (1) the ideological distance between chambers of Congress is smaller and (2) the ideological distance between Congress and individual district or circuit courts is greater. These findings suggest the administration of federal courts is influenced by the political concerns in another branch of government, raising important questions about judicial independence.