The dissertation addresses the equivalence regime in Union law. Although not new, Brexit has brought this legal principle into focus. The achieved results are, however, not limited to the (future) relationship between the UK and the EU. Rather, it provides fundamental indications on third country market access into the EU by examining Brexit. It is about whether equivalence can replace Single Market passporting rights, whether the numerous equivalence provisions can be systematised and to what extent trends in third country regulation can be identified.