The United Nations treaty bodies were established to monitor the implementation of human rights by states parties. Through ‘General Comments’ – legally non-binding clarifications of treaty obligations – they have also influenced the development of international human rights law – for example, on the right to life and climate impacts. We address this phenomenon by establishing a twofold argument. First, we argue that General Comments are used by the committees to informally shape international law. They deliberately act as human rights law-makers, knowing that international institutions, organizations and professionals in their network will subsequently refer to such instruments. Second, we argue that treaty bodies not only rely on their network once they have adopted their outcome, but the experts’ personal networks also shape the drafting process of General Comments. We develop and illustrate an analytical framework with two case studies of General Comments on the human right to water and the torture prohibition. The analysis demonstrates the need for external knowledge of both technical and legal aspects of the norms being interpreted. By addressing pressing human rights challenges, expert committees can shape the law in times of stagnation and resist contestation even from powerful states.