Contemporary American federalism, while characterized by nationalized policy battles in the states, is also increasingly defined by the centralization of power in the federal judiciary. In this introductory piece of the 2023–2024 Annual Review issue, we unpack the judicialization of federalism politics. This process, we argue, has been facilitated by national political gridlock, defined by increasing dysfunction in Congress, and the growth of the administrative presidency. In policy conflicts on subjects ranging from education and the environment to abortion and other individual rights, courts have played an increasingly significant role as the arbiter of the federal–state balance of power. As the articles in this Annual Review illustrate, with a few exceptions, judicialization of federalism has often resulted in the devolution of authority to the states, with significant implications for public policy and democratic institutions.