It is often said that the only constant is change itself. As time passes, the population grows, new technologies are invented, and the skills, demographics, and norms of the populace evolve. These changes, whether in isolation or in aggregate, influence the effectiveness of policy. In particular, policies designed for today’s world are unlikely to provide a perfect fit tomorrow. We develop a notion of policy decay that captures this impact formally. We introduce policy decay into a paradigmatic model of legislative policymaking and show that it leads to a starkly different perspective on legislative politics. Our results upend the classic notion of gridlock, and bear implications more broadly for the practice of politics. We show how a changing world impacts the power of agenda control, how it drives the dynamic path of legislation, how it reveals a novel conception of policy expertise, and how it, ultimately, provides a foundational logic to the design of bureaucracy.