Joint research project examines the role treaties will play in a post-Brexit constitution.

As Brexit negotiations rumble on with no sign of resolution, researchers have suggested that we could make  future government negotiations easier by giving Parliament a larger role in treaty-making.
The authors argue that the best forum for treaty politics is Parliament, and that by changing the rules for treaty scrutiny we can provide stronger democratic accountability and also make it easier for the government to negotiate, conclude, and implement treaties.

The collaborative project, conducted by researchers at the Universities of Oxford, Bristol and the House of Commons Library, examines the role that treaties will play in the post-Brexit constitution. The findings from the paper and a conference held to discuss the findings earlier this year, were presented last week at Parliament in a public lecture at the House of Commons Library.
Treaties shape the way that the UK will leave the EU, but they assume a new and more urgent importance because the UK is leaving the EU. Issues such as agriculture, fisheries, and trade are currently closely regulated by EU law and by treaties between the EU and third states. Brexit is intended to give the UK a greater measure of control over these rules. By this logic, in order to regulate these issues after Brexit, the UK Government will need to conclude more treaties, and rely less on EU law-making processes. With Brexit, treaties will therefore assume a greater role in the governance of the UK. However, unless something is done, democratic scrutiny of treaties will actually diminish. 
The paper’s core argument is that, if we want to meet the challenges posed by Brexit, we ought to pay closer attention to the constitutional rules that decide how Britain makes treaties. Brexit is bound up in treaties. The Gina Miller case was a debate about the nature and extent of the government’s power to make and unmake treaties. But this was only one legal strand in a much wider constitutional thread – a bigger argument about the power to make treaties. Since then, some members of Parliament have demanded that Parliament should have a “meaningful vote” on the terms of a Withdrawal Agreement, which is an international treaty. Others have demanded that the electorate should have the right to approve the terms of the treaty in a referendum.
Ewan Smith, co-author and Shaw Foundation Junior Research Fellow at Jesus College and the Oxford Law Faculty, said:
Brexit will put pressure on Britain’s system for negotiation, conclusion and incorporation of treaties. The more we rely on government-by-treaty, the more our constitution will need to regulate the politics of treaty-making. Treaties are political. All governments face challenges in persuading the public that compromise is needed to achieve foreign policy goals. If people are not satisfied by the compromises embodied in the Treaty of the EU, then there is little reason to suppose that they will be satisfied by the presence of chlorinated chicken in supermarkets, or the need to grant freer movement in return for market access.

The issue is, of course of public concern, but it is also technical. Other countries, including Canada, New Zealand, Australia and the EU all suggest different ways in which parliament and the government can work together in concluding treaties, without compromising the government's ability to conduct its foreign policy. The presentation at Parliament included discussion of practical solutions to treaty issues such as a new Parliamentary committee charged treaty scrutiny, as well as practical solutions for parliamentarians going forward.