Individuals’ equal right to make their own decisions and to control their own lives is fundamental to realising human rights. The United Nations (UN) Convention on the Rights of Persons with Disabilities confirms this axiom by obligating States Parties to ensure that all persons with disabilities, including those with intellectual disabilities (ID), have the right to self-determination. However, the means by which this right can become a reality is poorly understood, and as yet very little information exists about how this right is implemented in actual state practice. This article applies five core human rights principles by which to evaluate how well states protect the right to self-determination for persons with ID. It uses this set of principles to assess Norway’s performance. The article finds that despite Norway’s commitment to protect self-determination, denial of the right is widespread. Strikingly, the right to self-determination is consistently denied because of disability status, and does not involve a careful case-by-case balancing of human rights principles. Violations occur because self-determination is not treated as core to human rights realisation, and because many persons with ID are presumed incompetent to make decisions. Given these results, the article provides advice on how to improve practice.