Brexit is the 'largest' and most difficult legislative task a UK government has ever faced

The task of withdrawing Britain from the European Union is so massive and complex that it threatens to overwhelm MPs and civil servants, according to a new report published by a group of senior academics.

The report, entitled Brexit And Beyond: How The United Kingdom Might Leave The European Union, outlines the main hurdles Theresa May's government must overcome in order to successfully manage Brexit.

"We did not write this report to say Brexit is impossible or will be messy," Professor Anand Menon said at the report's launch in central London on Wednesday morning. "We wrote this so the problems can be addressed more effectively."

The report was produced by UK in a Changing Europe, an independent group of academics headed by Menon.

It warns that the government's plans to transpose all EU law which currently affects the UK into domestic law, dubbed the 'Great Repeal Bill', will be the "largest legislative task" ever undertaken by parliament and will pre-occupy MPs well into the next decade.

Here is a key extract from the 28-page report (emphasis ours):

"... By far the bigger task will be transposing into domestic law all the EU law which currently has direct effect in the UK, and amending the thus-augmented body of UK legislation which gives effect to EU law so that it can stand independently. The planned 'Great Repeal Bill' may give only blanket authority for these tasks. Legislative amendments will also be required if there are to be policy changes made possible because the relevant policy area has been repatriated to the UK, although legally these changes could not be made before Brexit occurs. Taken together, this body of work is widely regarded as the largest legislative task the UK Parliament has ever undertaken."

"The prospect that the legislative 'heavy lifting' of Brexit will be done through huge volumes of hastily-drafted and poorly-scrutinised secondary legislation has raised concerns about the democratic legitimacy of the project, and of the opening-up of legal 'black holes'. It is also not clear that all of the job could be completed until the terms of the UK's future - or at least transitional - relations with the EU are settled, which may not be until only shortly before Brexit occurs. Brexit will thus impose a major legislative burden well into the post-2020 Parliament."

It is not just MPs who face the prospect of an incredibly busy few years but civil servants, too.

The Brexit ministries have been trying to recruit hundreds of talented negotiators ahead of complex talks but cuts to personnel over the last few years have left civil service "depleted" and with little expertise, the report warns.

This could become a big problem when Whitehall is expected to handle the huge task of delivering Brexit while also trying to continue dealing with domestic policy, a juggling act which will "stretch" the service's capabilities.

"... a depleted Whitehall will also be expected to deal with domestic policy agendas. Inevitable crises will emerge. Whether a machinery that will be focused on Brexit-related matters will be sufficiently agile to develop comprehensive policies to address purely domestic agendas is questionable. Tensions will emerge about the lack of initiatives that will place ministers in the limelight of the media, especially as Brexit-related negotiations get bogged down in the kind of details that political masters find unappealing."

The publication of the extensive report comes as pressure continues to mount on the prime minister to disclose more details of the government's negotiation position to parliament. Labour's shadow Brexit minister, Keir Starmer, accused the government of telling Nissan more about its Brexit plans than MPs, after Business Secretary Greg Clark revealed he told the car company that the UK would seek tariff-free access to European markets.