Building on the separation-of-powers approach in American politics, this article develops a new micro-level account of judicial decision-making in contexts where judges face institutional insecurity. Against conventional wisdom, I argue that under certain conditions the lack of judicial independence motivates judges to “strategically defect” against the government once it begins losing power. The result is a reverse legal–political cycle in which antigovernment decisions cluster at the end of weak governments. Original data on more than 7,500 individual decisions by Argentine Supreme Court justices (1976–1995) are used to test hypotheses about why, when, and in which types of cases judges are likely to engage in strategic defection. Consistent with the theory's predictions, the results of the analysis show a significant increase in antigovernment decisions occurring at the end of weak dictatorships and weak democratic governments. Examining subsets of decisions and controlling for several additional variables further corroborate the strategic account.