You are here:

House of Commons Library

Brexit: some legal and constitutional issues and alternatives to EU membership

Published Thursday, July 28, 2016

This paper considers how the UK will leave the EU, some legal and constitutional issues, and possible alternatives to EU membership. What is the process for leaving the EU? Will the UK join a different grouping of states or go it alone? Will EU or UK citizens or businesses have any vested rights?

Jump to full report >>

EU Treaty provisions on withdrawal from the EU

Article 50 of the Treaty on European Union provides for a Member State to leave the EU, either on the basis of a negotiated withdrawal agreement or without one. The withdrawal agreement will probably contain transitional arrangements and it, or a separate agreement, will provide for the UK’s future relations with the EU.

There is no precedent for such an agreement, but it will probably come at the end of complex and lengthy negotiations. These will not start until Article 50 is triggered by formal notification that the UK intends to leave the EU.

The new Prime Minister, Theresa May, has said she will not trigger the Article 50 process before the end of 2016. There has been a debate as to whether the UK Parliament needs to approve the triggering of Article 50.

The EU institutions and other EU leaders want to keep to the Article 50 procedure: no negotiation until notification. But German Chancellor Merkel has said the UK should be allowed time to define its negotiating stance.

Will the devolved administrations have a role in Brexit?

The new Prime Minister, Theresa May, has assured the leaders of the Devolved Administrations that they will be involved in Brexit. But how will this happen? It is not yet clear how the devolved Parliaments or the Westminster Parliament will scrutinise or be otherwise involved in the Brexit process.

Acquired rights

The withdrawal agreement is likely to cover many individual rights. But if there are areas not covered by a withdrawal agreement, or if the UK leaves without an agreement, would British citizens and businesses in Europe – and European citizens and businesses in the UK – be able to rely on any ‘acquired rights’ (also referred to as ‘executed’ or ‘vested’ rights), either under EU law or general international law? The EU Treaties say nothing about rights acquired during the currency of the EU Treaties automatically continuing after a Member State leaves the EU. There is no explicit ‘survival clause’ protecting acquired rights or covering the survival of claims based on EU law.


General international law principles of certainty, stability, non-retrospectivity and mutual interest suggest some kind of continuing protection for individuals when the UK leaves the EU. But with no EU ‘survival clause’, where would this protection come from? The 1969 Vienna Convention on the Law of Treaties probably protects only the rights acquired under a treaty by states, not by individuals; and customary international law might protect some individual rights acquired under a treaty, but the scope of these rights is not clear and might not extend to rights of residence, for example.

Alternatives to EU membership

The UK might seek to join the European Free Trade Association (EFTA), remain in the European Economic Area (EEA) and therefore continue to have access to the single market. But this would mean allowing the free movement of people and contributing to the EU Budget. Norway, for example, provided around £586 million in 2014, or £115 per capita; the UK’s net EU budget contribution in 2014 was £9.8 billion, or £152 per capita.

Or the UK could decide to go it alone and negotiate bilateral agreements with the EU along the lines of the Swiss model.

The UK might decide to confirm and enhance its historic ties with other English-speaking nations in the ‘Anglosphere’. The Government is already talking informally with Australia about future trade relations.






Commons Briefing papers CBP-7214

Authors: Vaughne Miller; Arabella Lang; Ben Smith; Dominic Webb; Daniel Harari; Matthew Keep; Paul Bowers

Topics: Central government, Constitution, EU law and treaties, EU political integration, Europe, International economic relations, International law, International politics and government, Parliament

Share this page

Stay up to date

  • Subscribe to RSS feed Subscribe to Email alerts Commons Briefing papers

House of Commons Library

The House of Commons Library provides research, analysis and information services for MPs and their staff.