The claimants — consisting of one Remain and one Leave voter — say they're taking their case to the High Court to try and remain in the single market, or at least give MPs the chance to vote on the matter, which could give lawmakers the power to block any attempts to pursue a 'Hard Brexit.'
The two men, Peter Wilding, chairman of the pro-Europe pressure group British Influence, and Adrian Yalland, a conservative lobbyist and Leave voter, say their High Court bid is not designed to block Brexit, but aimed at ensuring the UK gets a "win-win, smart Brexit; not a lose-lose ideological hard Brexit which will damage the UK."
Mr. Yalland told the Sunday Times the legal challenge is based around the argument the government alone may not necessarily have a mandate to leave the European single market.
"The government thinks we leave the single market 'automatically' when we leave the EU. I think they could be wrong. So my judicial review will ask the court to decide who is correct. Why does this matter? Well, because membership of the single market is the 'ace' card which the EU obviously wants in its hand during the Brexit negotiations."
"But if the UK can trigger Brexit and not be forced out of the single market then the 'ace' card is actually in the UK's hands, which significantly enhances the UK's Brexit negotiating position."
Brexit Legal Woes Continue
If the court rules in Mr. Yalland's favor over the issue of single market membership, he says the government would then also need to trigger Article 127 of the Lisbon treaty.
In order to do this, he argues that the government might need the permission of parliament, which could then set up the situation where lawmakers could reject any plans aimed at taking Britain out of the single market.
The fresh legal challenge comes as the government faces being forced to get parliament's approval to trigger Article 50, which officially kicks off the EU divorce process.
While prime minister May initially suggested the government would use a Royal Prerogative to trigger Article 50, a High Court challenge found that lawmakers must be given a say on the matter.
The government has since made its arguments to the Supreme Court to try and overturn the decision, with a decision expected within the next few weeks.