An effective terrorism alert system in a federal government has one central task: to motivate actors to take costly protective measures. The United States' color-coded Homeland Security Advisory System (HSAS) failed in this mission. In federal systems, national leaders cannot compel protective actions by setting an alert level; they must convince constituent governments and private parties that the desired actions are worth the costs. Such beliefs can be generated either by sharing the information behind an alert or by developing enough confidence in the alert system that the government's word alone suffices. The HSAS did neither, largely because it was not designed to generate confidence. Rather, the system's creators assumed that the public would trust the national leadership and believe in the utility of the system's information. Over time, as the HSAS became increasingly perceived as politically manipulated, there was no built-in mechanism to recover confidence in the system. An alternative, trust-based terrorist alert system could solve this problem. Building on the notion of "procedural fairness" from the psychological and legal traditions, this system would retain the political advantages of the HSAS, facilitate greater compliance among the requisite actors, and ameliorate many of the strategic problems inherent in terror alert systems.