Few studies on federalism analyze the role of courts as safeguards of the federal arrangement, and those that do tend to be too optimistic about what courts can do. This article analyzes the effect of judicial review on the interaction between the central and a regional government in a federation in order to understand the conditions under which courts may or may not enforce compliance with federalism. It argues that politicians of either level of government anticipate the likelihood of a judicial challenge and an eventual veto, and it finds distinct equilibria in the interaction between central and regional governments (imposition, auto-limitation, negotiation and litigation). Only under auto-limitation do courts effectively prevent transgressions to the federal arrangement. In all other scenarios, defection may take place despite the presence of courts. These findings show that as the court's jurisprudence becomes more solid and defined, the chances for governments to successfully exceed their powers increase. Not only do transgressions take place despite the presence of the court, but because of it.