The aftermath of the UK’s referendum vote to leave the European Union has been dominated by uncertainty as to what ‘Leave’ really means. At the heart of this uncertainty are competing visions of the UK’s future trade relationship with the EU and its Member States. More particularly, much has been made of an apparent difference between ‘accessing’ the EU Single Market and ‘membership’ of the Single Market. But as the UK seeks to define and negotiate a new trading relationship with the EU, ‘Brexit’ itself dramatizes deeper debates about the nature and conduct of global free trade. The issue is not merely one of which model the UK should, or could, adopt, but also what these models tell us about the possibilities for, and limitations of, ordering trade relations in the world on a regional, bilateral, multilateral or sectoral basis. At the same time, the politics of trade is itself increasingly under the spotlight. In the UK’s referendum and in the US Presidential election, Left and Right politics each displays conflicting views about the value of, or threat from, free trade. The argument that underlies the lecture is that while Brexit is a phenomenon to be studied, it can only be understood in terms of the wider law and politics of global free trade.