This chapter begins with an overview of the relevant international legal framework for conscientious objection. It identifies the main instruments relating to this principle, originating in the Universal Declaration of Human Rights (UDHR) then developed and integrated into others with a global reach, such as the International Covenant on Civil and Political Rights (ICCPR). In addition, it also considers those restricted to Europe, in particular the European Convention on Human Rights (ECHR) and outlines the structure of related international judicial and regulatory bodies. It leaves consideration of other supranational legislation—which have no bearing on Europe—together with their judicial and regulatory bodies, to the non-European chapters to which they have most relevance. This chapter then focuses on the principle of conscientious objection, its legal definition and interpretation. It explains how this principle has grown to transcend its initial confinement to a military context and considers how it now relates to the principle of State neutrality. The chapter proceeds with an examination of conscientious objection in a human rights context, beginning with the fundamental rights: the freedoms of expression, association/assembly and religion. This sets the scene for an exploration of contemporary caselaw, illuminating varying aspects of the relationship between conscientious objection and the provisions of equality and non-discrimination legislation, as experienced in public and private service provision settings. This chapter is central to the book as it identifies and justifies a taxonomy of issues and themes arising from the case law study that will structure the jurisdiction specific exploration of Part III, and provide a basis for the subsequent cross-jurisdictional comparative analysis.