Professor Kenneth Armstrong, University of Cambridge, gave a lunchtime seminar entitled "To Align or Not to Align? - Market Regulation after Brexit" on Wednesday 6 November 2019 at the Faculty of Law. Membership of the European Union requires Member States to implement EU rules and align their legal frameworks to ensure that domestic legal rules faithfully and continually reflect the market regulation requirements imposed by EU law over time. Apart from the generic provisions of the European Communities Act 1972, remarkably little attention has been paid to the mechanisms and instruments by which UK law has aligned with EU law during membership. The UK’s withdrawal from the Union and the aim of the European Union (Withdrawal) Act 2018 to ensure perfect domestic alignment as of ‘exit day’ provides a novel opportunity to reflect on how alignment has been achieved during membership and how that might change post-Brexit. And while much of the media attention lies on the big political choices facing the UK as to whether to pre-commit to alignment under a so-called Norway model or instead to have regulatory autonomy to pursue free trade deals (or a mixture of the two in respect of the Irish ‘backstop’), very little is understood as to how alignment will be secured through legal mechanisms and legal instruments. This paper explores the past and future of regulatory alignment in the UK when – and if – Brexit occurs. For more information see the CELS website at http://www.cels.law.cam.ac.uk/