Substantive equality in part-time work. The evolving protection of the Part-time Work Directive

This article examines how the protection against discrimination based on part-time work has evolved towards a model of substantive equality in the case law of the Court of Justice of the European Union (CJEU). The focus is on the non-discrimination clause in the Part-time Work Directive and conditions of pay, and Norwegian law is used to illustrate the issues and the impact on national law. The analysis starts by highlighting important aspects of the non-discrimination clause; the fundamental question of what constitutes different treatment, the requirements to justify it and the role of the principle of pro rata temporis . From there, the developments in case law in cases concerning conditions of pay are further scrutinised. The analysis explores two diverging approaches to what constitutes different treatment, developed in case law on the principle of equal pay for male and female workers and highlight how they align with the concepts of direct and indirect discrimination. The article further dwells on how this broad model of equality is confirmed and clarified in recent case law on the Part-time Work Directive, by applying the principle of pro rata temporis . The analysis of justification requirements also explores the problematic nature of conditions of pay that appear to be equal but have adverse effects in part-time work. Although these developments bring the protection against discrimination based on part-time work in line with protection against discrimination on other grounds in EU law, they challenge national regulations on overtime pay and other remuneration supplements, as in Norwegian law.