The Weight of Precedent: Parties, Trust, and Executive Norms

Political executives often adhere to traditions set by their predecessors that establish expected behavior, such as informal limits to their power. However, it remains a puzzle why executives follow norms, which lack legal backing, when they face incentives to violate them. To address this question, we analyze an infinite-horizon formal model incorporating within-party and across-party dynamics to examine when informal constraints on executives persist or collapse. Norm survival hinges on an executive's willingness to transgress a norm and their party condoning this act. The driving mechanism is coordination: violating a norm degrades cooperation between the executive and their party. We also show that the same conditions can support a high-trust equilibrium among parties in which norms survive and a low-trust equilibrium of preemptive violation. Trust-driven collapse is greatest under balanced party competition. The model classifies executive norms by fragility and traces the life cycle of the American presidential two-term tradition.