This article uses a diachronic study of Argentina to explain how the nascent democracies of Latin America build the rule of law. The changing relationship between Argentina's executive and judicial branches demonstrates that the construction of the rule of law is not a linear process. There have been periods of regression away from, as well as progress towards, the rule of law. This article uses party competition to explain Argentina's varying levels of judicial independence. The rule of law results from a balance of power between at least two political parties, neither of which has monolithic control, meaning that no highly disciplined party sustains control of both the executive and legislative branches. Competitive politics creates a climate in which an autonomous judiciary can emerge.