Chapter 3 focuses on the practical side of the legal advisers’ work. Through concrete examples, it describes what they do and how they work. It also traces the specific expertise that EU legal advisers have. Previous studies on the forms of expertise in policy-making and adjudication, including that of the EU and in international contexts, have focused on forms of scientific and technical expertise, but have largely omitted the question of legal expertise. Apart from their knowledge of EU institutional and constitutional law, legal advisers also possess expertise on institutional practices and agendas. This is an important part of what makes their expertise – in common with most professional communities – specific.