This article argues that governmentality perspectives provide a fruitful way to analyse the complex interactions between disability and the law, using Article 12 of the Convention on the Rights of Persons with Disabilities (CRPD) and mental disability as a ‘case study’. The governmentality literature recognises that the law is implicated in the truths, knowledges, rationales and practices through which disability is rendered known and knowable. From this perspective, a governmentality approach provides a framework for considering the complex and contradictory relationships between capacity, disability and law. This article analyses the concept of legal capacity in Article 12 and its challenge to mental capacity as a central principle in developed Western legal systems. The article shows that rights claims in the second half of the twentieth century reinforced the classical privileging of cognitive ability and rational capacity as a threshold requirement for citizenship. As a consequence, capacity and inca...