Untangling Britain from decades of European legislation would take years and could create constitutional mayhem, according to legal experts.
“EU law is part of UK law and its adoption has given UK citizens, companies and public authorities rights and duties,” said Professor Sionaidh Douglas-Scott, a constitutional law expert at Queen Mary University of London. “Repealing or amending them would be a complex and demanding process. Serious detriment and havoc will be caused to the British constitution in the process.”
Britain’s exit from the EU, Prof Douglas-Scott says, would require the repeal of legislation such as the European Communities Act, the mechanism by which EU law is brought into the body of UK law. But a big complication is that the ECA and other primary legislation implementing EU laws are incorporated directly into the devolution statutes in Scotland, Wales and Northern Ireland.
The Scotland Act 1998 states that acts of the Scottish Parliament which are not compatible with EU legislation are “not law”. Similar provisions exist in the Government of Wales Act and the Northern Ireland Act.
“If the UK government insists that powers repatriated from Brussels go to Westminster [after a vote to leave the EU], this could set Westminster and Holyrood on a collision course,” said Andrew Scott, professor of European Union Studies at the University of Edinburgh.
For instance, control over agriculture and fisheries policy, handed to Scotland at the time devolution was enacted because the EU was assumed to have responsibility in this area, would “default” to Scotland in the event of Brexit, Prof Scott said. “That would then set up a major constitutional problem because the UK government would be likely to want to retain control over these areas.”
By convention, Westminster must seek the consent of the Scottish parliament for legislation on devolved issues. Any attempt by a UK government to force through changes would be likely to provoke outrage in Scotland — where polls suggest a majority intend to vote to remain in the EU — and boost support for a second independence referendum.
Meanwhile, the Belfast or “Good Friday” Agreement of 1998 includes provisions based on the ECA and the European Court of Human Rights. And lawyers say the status of the UK and Ireland as EU member states was “woven throughout the agreement”.
In addition to these potential constitutional wrangles, extricating Britain from the EU’s legal embrace would require identifying which laws were no longer applicable or needed to be redrafted, and which should be revoked or replaced.
“The UK would have to decide which parts of EU law it wished to keep and which to jettison,” said Philip Wood QC, head of Allen & Overy’s global law intelligence unit. “Antitrust, financial regulation and pensions would be only examples of numerous complex areas.”
Simon Gleeson, a partner at Clifford Chance, described the resources required to enshrine Brexit within UK legislation as “monumental”. He said: “It will be simply impossible to do any comprehensive review of EU legislation before any reasonable exit date.”
The simplest option for the government — to translate existing EU law into British law in a single “Brexit Act” — is possible but politically dangerous. “The degree of pruning [of EU law] could be highly political since the electorate might be saying they wanted to leave the EU, not take it with them,” said Mr Wood.
Some EU laws — such as rules on enforcement of judgments and the allocation of jurisdictions — cannot be transposed wholesale because they must be reciprocated by Britain’s EU partners.
Other laws would also require the agreement of former partners in the bloc. “Passporting”, which allows financial services firms based in the UK to operate without further authorisation across the EU, is one example.
“Some of the rules are premised on the fact that there is access to a wider European market — for example, regulation of financial institutions,” said Martin Coleman, a partner in a global law firm and a member of a pro-Remain group called “Lawyers — In for Britain”.
The nature of the British legal system poses particular challenges for those wanting to roll back existing EU legislation: much of it has been incorporated into British law and tested in the courts, and has thus become part of case law. This means that, even if a statute is removed, its principles — for example, on legislation governing workers’ rights — would remain in force.
“If the courts have concluded that the correct approach to X is Y, if you just take the statute away, that approach will continue,” said Mr Gleeson at Clifford Chance.
Others point out that, although previous rulings by the European Court of Justice would probably be challenged in court after a British exit, there would be no direct return to the status quo before the UK joined the European Economic Community in 1973. The exact status of case law generated during the UK’s membership of the bloc would thus become dangerously murky.
“If some EU law is retained in domestic law post-withdrawal, what would be the mechanisms used to interpret it?” said Prof Douglas-Scott. “Would UK courts revert to pre-1972 understandings of UK law, or would they continue to look at EU law and decisions of the European Court of Justice to interpret British law?”
Furthermore, new domestic laws would have to be introduced to fill gaps where the EU currently has competence — for example, in the licensing of medicines — added Prof Douglas-Scott.
Whatever type of legal divorce takes place post-Brexit, it will tie up resources for years to come. “You have to think of it as a reverse accession [to the EU]. It’s the whole of the civil service for a decade,” said Mr Gleeson.
Daniel Shurman, a partner at Allen & Overy, called it “the biggest demerger in history — the world’s fifth-largest economy leaving the world’s largest trade bloc”.
He added: “If one wanted to rewrite the many thousands of pages [of relevant legislation] from the start it would obviously be an incredibly complex and time-consuming task and I don’t think people have fully fathomed the challenge.”