This chapter examines how internal self-determination is understood and applied by courts of law. The ICJ's jurisprudence is silent on internal self-determination, even though Separate Opinions of judges contain helpful discussions about the principle and its relevance in a post-colonial world. After the discussion about the jurisprudence of the ICJ, the chapter focuses on two specific cases decided in domestic courts. These are two cases decided by the Supreme Courts of Canada and Sri Lanka, respectively. In doing so, the chapter shows how domestic courts approach issues of internal self-determination. The chapter argues that domestic courts generally tend to acknowledge the relevance of internal self-determination and its application to peoples within states. The courts are however cautious in discussing aspects relating to internal self-determination.