Leaving the European Union would not be a gain for liberty in the United Kingdom. This is true as a matter of general principles and is reinforced by the nature of the Leave campaign which has targeted sections of the population hostile to immigration, open markets, and free trade. Much of the Leave campaigning which has not appealed to such base arguments has at the very least appealed to a version of populist democratic sovereignty at odds with the restraints on government and the state at the heart of classical liberal and libertarian thought.
Even if we try to separate some pure classical liberal version of the Leave campaign from the crudity of the campaign, as some natural supporters of leave wish had happened to the extent they ate voting for Remain rather than go along with such an obnoxious campaign, we are still left with the question of why it liberty advocates should support Leave.
I have sometimes seen references to national sovereignty as a classical liberal doctrine. If this means never sharing sovereignty at a transnational level, then it is simply a false claim. Immanuel Kant advocated a world federation to prevent war. Kant is not often put at the centre of the history of classical liberal thought. His ideas about political institutions, individual rights, and the limits of government certainly belong in the classical liberal sphere. We should distinguish between what Kant said and what later German Idealists said, a rather big issue, and appreciate how close he is to the way of thinking of Montesquieu and Smith and even advances upon them in showing a clearer understanding of the role of representative assemblies in modern politics.
More recently F.A. Hayek advocated federation between liberal democracies. The creation and evolution of the European Union has been and continues to be supported by European political parties of a classical liberal persuasion, those liberal parties which remained most true to the principles of their nineteenth century founders and precursors. Thinkers on the left, like Albert Camus and George Orwell, known for their particular commitment to liberty and their opposition to an authoritarian state were enthusiasts for European integration. Many conservatives of the more free market and limited government sort like Ludwig Erhard (founder of Germany’s post-war, post-Nazi market economy) and John Major (UK Prime Minister from 1990 to 1997, who went further than Margaret Thatcher in privatisation and deregulation) have been and are advocates of the European Union.
The unrestrained sovereignty of the nation-state is not only not an inherently liberal idea, it is dangerous to liberalism. There is nothing illiberal in transnational rules and institutions that restrain states from violence against their own citizens, attacks on individual rights, economic protectionism, and market rigging. The European Union is particularly successful with regard to the economic and market issues at the national level. It adds huge institutional weight to the work of the Council of Europe which promotes human rights through its court in Strasbourg. The existence of the European Court of Justice is of profound importance in ensuring that national governments and peoples are accustomed to regarding the decisions of nation states as subordinate to and accountable to a judicial process enforcing transnational laws.
The EU is open to a great deal of criticism with regard to its tendencies towards over-regulation, but this represents the median attitude of the member governments, not an imposition on the nation-states of Europe. Since the UK economy is at the more free market deregulated end of the European Union, there is some plausibility in saying the UK might go further down that road if it left the EU. However, before it joined the EU it was looking less market oriented than the EU states of the time. The period during which the UK has moved from the more statist to the more limited state end of the European nations has been during the period of EU membership. The precedents do not favour the UK becoming more classically liberal because it leaves the EU and the Leave campaign has appealed to the most insular, nationalist, anti-immigrant, anti-foreigner, and anti-free trade sections of the UK population.
It is possible to imagine the UK as a more libertarian kind of place in the EU, but a much more plausible use of the liberal imagination is to think of ways in which the UK can work with allies in the EU for a a less regulatory and centralised EU. This has already worked as in the adoption of the European Single Market and the diminishing role of the European Commission, the ‘bureaucratic’ part of the EU. The Commission employs as many bureaucrats as the larger local government units in the UK and is tiny compared with any national bureaucracy. Its members are nominated by national governments subject to confirmation of the European Parliament. Power has shifted from the Commission to the bodies in which national government representatives meet, the European Council and the Council of the European Union.
The Leave campaign in the UK, including self-styled free marketers in the Conservative Party, is committed to leave the Single Market as well as the European Union itself, in large part to terminate free movement of EU citizens across its borders. The reasoning offered to prevent this movement of human capital is in terms of anti-foreigner sentiment. This is not something than can be recognised as a pro-liberty program. The pro-liberty choice is to keep free movement of goods, investment, and labour within the EU while working to reform the more interventionist tendencies of the European Union, to stymie the regulatory drift which started hitting industrial market economies decades before the EU was created and which cannot be solved by smashing up the EU.