Oliver Letwin, who is leading the Whitehall team preparing for negotiations on the UK’s exit from the European Union, announced yesterday that the government’s lawyers understand Article 50 can be invoked without parliamentary approval. The prospect of having to put the decision to a vote in the Commons – where a majority of MPs were in favour of the UK remaining in the EU – had been held out by supporters of continued membership as a potential block on the decision to leave.

We have carefully analysed the legal position on Article 50 with leading constitutional law experts as we help our clients understand the exit process. The main argument for parliamentary approval surrounds the European Communities Act, which transfers the rights and obligations that flow from EU treaties into domestic law. Invoking Article 50 would take these rights and obligations away, and some have claimed this would therefore require the consent of the House as the government cannot lawfully extinguish rights conferred by Parliament.

The counter argument – which is now the government’s position – is that the Royal Prerogative could be used instead. This is a collection of executive powers held by the Crown (of which the government is part), some of which allow ministers to take decisions without parliamentary backing.

There have been announcements that a legal challenge would be launched in an attempt to establish that an Act of Parliament is required. If that challenge materialises, we expect proceedings to be expedited straight to the Supreme Court where the decision could be made within weeks. However our understanding of the situation in Westminster is that even if this were to be successful, Parliament is likely to approve the decision anyway, given that the majority of MPs are believed to support the will of voters as expressed through the referendum result.

If you would like a more detailed analysis, please read our briefing Article 50 and withdrawing from the EU