This paper provides the first overarching exploration and discussion of the relationship between law and compassion, based on a broad review of law and associated literature. The paper reviews the English-language literature worldwide, identifying and analysing key themes. It lays out a number of themes by which the relationship may be examined, including the problematic of defining compassion, addressing the concept of compassion, its components, to whom it is owed and under what conditions it is owed. The paper reviews how compassion is defined in formal law, including in case-law and legislation across a range of common-law and civil-law countries, and in international human rights and humanitarian law−revealing various judicial and legislative approaches to the place, meaning and application of compassion. The discussion of primary and secondary sources suggests a number of ways of thinking about the place or absence of compassion in law: how it helps theorise law, including its normative presuppositions and the conceptualisation of law. The paper concludes with consideration of possible pathways for future research on law and compassion.