The prime minister can trigger the two-year process of negotiating the UK’s withdrawal from the EU without a vote in parliament, government lawyers have advised.

Cabinet minister Oliver Letwin, who is heading Whitehall’s Brexit unit to prepare the way for negotiations, said the legal advice was that article 50 of the Lisbon treaty can be invoked under the royal prerogative, which does not require parliamentary approval. Article 50 is the clause that triggers the start of a negotiation to leave the EU.

There was growing speculation at Westminster that a new Conservative administration might not want to trigger the article until the end of next year due to the political vacuum created in the EU by the French and German national elections next year. Ministers might not wish to use up the valuable two-year negotiating time if they did not know the political context in which they would be negotiating for a year.

Speaking at parliament’s foreign affairs commitee, Letwin also confirmed that the government, apart from the Treasury and the Bank of England, had made no preparations for Brexit, prompting MPs to accuse ministers of a dereliction of duty.

He said his new Cabinet Office unit could prepare a “fine grained, multi-dimensional” options paper in time for 9 September, the date a new prime minister is to be installed.

The paper would look at different forms of co-operation with the EU, contributions to the EU, a successor to the common agricultural policy, tariffs, regulatory protection and the future of the City of London. He said the aim was to build a model from the bottom up, but insisted had no preferred package solution.

Letwin claimed that although government lawyers had said the triggering of article 50 was a matter for the royal prerogative and not parliament, MPs would have a role in the process of Brexit since it would require the repeal of the European Communities Act 1972.



At a separate hearing of the Treasury select committee, leading constitutional lawyers revealed that the French government legal service has informed the French government that the UK would be entitled to rescind a notice to withdraw even though it had invoked article 50.

Such flexibility would mean that even if it was triggered, the UK could reverse a decision to withdraw, if either parliament or a second referendum endorsed the step.

Michael Dougan, professor of European law at Liverpool University, also pointed out that any UK application to join Norway as a signatory to the European economic area (EEA) agreement – a means of maintaining access to the EU single market – could be vetoed by any single one of the remaining 27 EU member states, the four members of the European free trade area (Efta) and the European parliament, meaning 31 different institutions or states could block the UK signing the EEA.

The EEA is seen by some as the best stopping off point for the UK, since it retains UK access to the EU single market, but all EEA members are required to apply the principle of the free movement of people.

The chances of the UK negotiating an exemption on free movement under the EU is sharply reduced if 30 different states and institutions could veto the agreement. Dougan said only armchair lawyers thought the EEA provided any flexibility on free movement of workers.

He added the legislative complexity of disentangling the UK from the EU will require a large surrender of power from parliament to executive. He also pointed out Britain would still be bound by the judgments of international courts under any significant international free trade agreement with other countries.

He said the UK would be bound by the rulings of an Efta supervisory court, and these were part of international law, making them binding on the UK.

He added: “In practice the scholarship from Norway and Iceland tells us there is not an enormous amount of difference from the effect of EEA law within those states [and the effect of EU law in EU member states].”