Legal action is being taken to ensure that the formal process for the UK’s exit from the EU is not launched without the consent of the British Parliament.
London law firm Mischon de Reya is acting for a group of business people and academics who say it would be unlawful for a prime minister to invoke Article 50 of the Lisbon Treaty without a full debate and vote in Parliament.
Triggering the article would formally begin the process of Britain’s withdrawal from the EU.
There is no legal requirement that Britain invoke the article within a specific amount of time, but once notice is actually given by the prime minister, there is a two-year time limit within which an exit deal must be negotiated.
The timeframe can be extended only with the unanimous agreement of the remaining 27 member states.
Lawyer Kasra Nouroozi says the result of the referendum is not in doubt, but it needs to be enacted through a formal process.
“We must ensure that the government follows the correct process to have legal certainty and protect the UK constitution and the sovereignty of parliament in these unprecedented circumstance,” Nouroozi told the BBC.
“The outcome of the referendum itself is not legally binding and for the current or future prime minister to invoke Article 50 without the approval of parliament is unlawful.
“We must make sure this is done properly for the benefit of all UK citizens. Article 50 simply cannot be invoked without a full debate and vote in parliament.”
A prime minister acting alone under prerogative powers technically lacks the constitutional authority to invoke Article 50 without being given the authority to do so by an act of Parliament.
As the referendum was advisory and non-binding, Westminster could technically refuse to ratify the vote. About two thirds of MPs are pro-EU and could block the whole process.
However, as 52 percent of the population voted for 'Leave,' it is highly unlikely that Parliament would block a Brexit, as it would be seen as undemocratic.
London and Brussels appear to have reached a stalemate since the June 23 Brexit vote, as the EU has ruled out any possibility of holding informal talks on Britain’s exit before it invokes Article 50.
However, outgoing Prime Minister David Cameron, who in the aftermath of the vote said he is stepping down, is resisting pressure to begin the two-year talks process as quickly as possible, insisting that it is for his successor to decide when to issue the country’s formal intention to leave the bloc.
A new PM is expected to be in place by September.
There have been a number of arguments put forward as to how the UK’s departure from the EU might be slowed or stopped.
By law, the UK’s legislatures in Wales, Scotland, and Northern Ireland must be consulted before EU laws can be annulled – which could throw a monkey wrench into EU Brexit negotiations.
Northern Ireland and Scotland voted to 'Remain' in the EU.
Scottish First Minister Nicola Sturgeon said she would tell MPs to refuse “legislative consent” if the Scottish parliament is required to ratify the UK’s withdrawal.
There have also been calls for a referendum re-run. A petition demanding another vote has already collected over four million signatures.