Brexit Paper 25 - Internal Market and Customs Union

6 December 2017



Bar leaders have published a paper tackling issues raised both by the Irish border question and the vision for 'frictionless' trade set out by the Prime Minister earlier this year.

'Brexit Paper 25: The relationship between the single market, the customs union and the European Union'

Brexit Paper no. 25 looks at the legal and historic links between the EU, the internal market and customs union, and how the UK could negotiate a reduced role for the ECJ as well as tighter controls on EU worker migration while protecting key economic interests.

Chair of the Brexit Working Group, Hugh Mercer QC said:"By building on the legal framework covering the UK's existing opt-outs, the Government could solve some of the most difficult issues in the current talks while keeping the power to negotiate bi-lateral deals on agriculture, fisheries, competition, trade and environment, which would end the ECJ's jurisdiction in those areas."

According to the report's authors, the ECJ would no longer have jurisdiction to interpret rights derived from EU citizenship in the UK and a deal could be struck to confirm UK sovereignty over internal market and customs union matters and to define clearly the status of ECJ rulings in those areas.

Hugh Mercer QC said:"Opting into the internal market and customs union could be negotiated along-side a complete opt-out from the political elements of the EU and an overhaul of the scope and role of the ECJ so far as the UK is concerned. The status of its rulings and its jurisdiction would be significantly reduced and much more clearly defined to ensure the sovereignty of the UK Parliament."

The paper explains that a worker registration scheme could be used as part of a managed approach to migration, giving the Government access to data on the parts of the economy that draw in EU workers. Ministers would set the criteria to refuse admission or deport those who are not in employment, and Parliament would set the terms on which EU citizens access social security and pass employment laws to support British workers.

Chair of the Bar, Andrew Langdon QC said:"The UK is at a crucial stage in the negotiations and the legal consequences of all the options available must be carefully considered. This analysis sign-posts some of the legal avenues that could help Government to manage the competing demands and priorities inherent in the negotiations."

One of the Bar Council's Third Edition Brexit Papers, published earlier this year, looked at the legal consequences of leaving the European Union without first agreeing a trade deal and the implications of relying on international trade under terms set by the WTO.

'Brexit Paper 25: The relationship between the single market, the customs union and the European Union' is available here


Notes to Editors 

1.   Further information is available from the Bar Council Press Office on 020 7222 2525 and

2.   The Bar Council represents barristers in England and Wales. It promotes: 

  • The Bar's high quality specialist advocacy and advisory services

  • Fair access to justice for all

  • The highest standards of ethics, equality and diversity across the profession, and

  • The development of business opportunities for barristers at home and abroad.

The General Council of the Bar is the Approved Regulator of the Bar of England and Wales. It discharges its regulatory functions through the independent Bar Standards Board