While prior studies have suggested that legal strategies offer promising tools for social accountability, the existing literature has not yet identified the underlying mechanisms that link legal strategies to accountability improvements. In this theory-building paper, we argue that there are four mechanisms by which legal strategies can enhance accountability. First, the courts can help those affected by policy failures to overcome the collective action problem. Second, courts can provide civil society with access to information about rights violations, malfeasance, and poor policy performance. Third, legal strategies can set in motion court-backed reforms that redress immediate rights violations and strengthen state capacity for more accountable governance. Fourth, court recognition can increase the symbolic and discursive resources of claimants, making their demands for accountability more effective. We illustrate these mechanisms through a comparative analysis of two policy arenas in Colombia, environment and healthcare – two areas in which civil society engagement with the judiciary opened up new routes for social accountability. By bridging the previously disconnected literatures on legal mobilisation and social accountability, this paper creates an analytical framework to understand the menu of options that citizens face about where and how to seek accountability from the state.