Equality is one of the principal political concerns of our times. The decline in economic and social equality within nation states gets increasing attention. This rising economic inequality is often cited as a major reason for the recent rise of political populism and therefore considered to be a danger to political stability. But economic inequality is not the only problem. Inequalities based on gender, race or nationality are also major issues in the contemporary discussion. While most commentators discuss political solutions, the proposed research project focuses on the contribution that courts can make to correct inequalities. Norms protecting equality form part of all major national and international human rights instruments. Still, the meaning of equality is fundamentally contested. There is no agreement on what equality exactly means or entails. In the legal context, equality is most often understood in a formal way. This formal conception of equality is associated with the Aristotelian idea that like cases should be treated alike and that unlike cases should be treated differently. However, as long as individuals are different, there will never be total equality. For this reason, the question is not whether legal equality guarantees can tolerate inequality, but to what extent they can do. Because of these conceptual difficulties, the application of equality and non-discrimination clauses is not a straightforward exercise, in which courts simply apply legal norms to a given set of facts. Instead, courts need to develop doctrinal instruments in order to give meaning to the concept of equality. The proposed research project analyzes how apex courts conceptualize equality in constitutional and international human rights law. It will be based on a comparative study of the equality jurisprudence of 16 jurisdictions and has three aims. Firstly, it intends to create a comparative map of equality jurisprudence, i.e. to describe and categorize the constitutional jurisprudence on equality: Which doctrinal choices do courts make and how do these choices inform the conception of equality? Secondly, it seeks to explain the doctrinal choices of the analyzed courts: Which factors influence courts to arrive at particular conceptions of equality? Thirdly, it has a normative goal and wants to analyze whether courts are better suited to correct certain kinds of inequalities than other kinds of inequalities.