With the return of democracy to the Latin American region, scholars have emphasized the role of the judiciary in countering two “dangerous tendencies” in Latin America: restrictions on fundamental democratic rights, such as freedom of expression, and the growth of centralized and unchecked presidential power (Gargarella 2004, 182). Under what political conditions are judges more likely to arbitrate political conflict over the use of power and mediate the relationship between state power and individual rights? This chapter addresses this question through a historical comparative analysis of the impact of internal and external conditions of the political environment on judicial activism against the executive in cases involving presidential use of exceptional authority and active judicial protection of the freedom of expression in Chile and Argentina. These two country cases exhibit markedly different historical relationships between the executive branch and the supreme court, yet judicial authority to review government action has expanded in both countries over the time period examined, roughly the 1940s–2000. Over these six decades, there has been considerable variation in judicial response to presidential use of exceptional powers and rights protections, more variation perhaps than traditional accounts of Latin American courts (to the extent courts were considered relevant for study at all) predicted.