This chapter begins with a brief overview of the historical background, leading up to the current social context that shapes the role for conscientious objection issues in England and Wales. It considers the relevant principles, policy and law. Starting with the principle itself, its legal definition and interpretation, it then traces the related policy developments before setting out the current international and domestic legislative framework, noting the ratification of relevant international treaties, conventions or protocols and identifying the main judicial and regulatory bodies. The chapter then moves on to examine the functioning of conscientious objection in the context of relevant contemporary domestic law. This central section focuses on the intersect between conscientious objection and the fundamental human rights: freedom of expression, association/assembly and of religion. Finally, the chapter then systematically examines in turn a sequence of distinct themes relating to the interface between conscientious objection and equality and non-discrimination law- public health, public social care, public education, national defence/asylum seekers, employment and commercial services—as addressed in domestic caselaw; assessing any significant trends and governing principles.