A legal challenge arguing the government has no power to push the Brexit button without the approval of Parliament is underway in London’s High Court.
Lawyers for protest group Fair Deal for Expats and the government are arguing a number of technical points about the British constitution.
The basic disagreement is over who has the right to decide whether Britain invokes Article 50 to leave the European Union.
The challengers say ministers must consult MPs before triggering Article 50 because only Parliament can make a law that repeals a law- referring to the statute that took the UK into the EU.
The government claims ministers can trigger the Royal Prerogative, a power that allows them to make decisions without the approval of MPs.
The case is expected to last several days.
Campaign to undermine Brexit vote
The wider argument is the challengers are trying to delay Brexit or even reverse the referendum vote to leave the EU, while the government claims the people have spoken and in the words of Prime Minister Theresa May: “Brexit means Brexit.”
“We are asking MPs to do the things we pay them for,” said Gina Miller, one of the campaigners who brought the case.
“Did the people who voted to leave really vote for the prime minister and a handful of her ministers to bypass Parliament?”
The referendum result was 52% in favour of leaving the EU and 48% for remaining, although the majority of MPs supported staying in the EU.
The single market controversy
May has told Westminster that she intends to start Brexit negotiations by the end of March 2017.
She has been criticised for failing to reveal details of Britain’s objectives in the talks, but has refused to discuss her approach as she is worried this could give EU negotiators an advantage.
The key issue is whether Britain would agree to keep EU freedom of movement rules to stay in the single market.
Leaving the single market would be seen as an economic disaster as the EU would likely raise tariffs against British exports, while remaining in the market is considered a political disaster as the issue of immigration and taking control of borders was key to the referendum vote.
