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The first legal challenge over Brexit is being heard in the High Court today as a hairdresser fights to stop the UK leaving the EU.

Deir dos Santos has launched a legal case arguing that the Government cannot push ahead on leaving the EU without Parliament’s backing.

His case suggests the prior authorisation of Parliament is required before the Prime Minister can trigger Article 50 of the Lisbon Treaty, which will start the formal process for Britain's departure from the EU.

Two senior judges are expected to set down a timetable today for a judicial review hearing later in the year on Article 50.

The application has been described by lawyers involved as "the most important constitutional law case in living memory".

Among the key issues judges will have to analyse at the full hearing is the true extent of the Prime Minister's executive powers.

David Greene, senior partner at law firm Edwin Coe, is instructing Dos Santos.

Mr Greene said: "Whilst Brexit is highly political, the issue before the court tomorrow is a basic question of the rule of law.

"The claimant submits that the course proposed by the Government is unlawful because only Parliament is empowered to authorise service of the Article 50 notice and consequent withdrawal from the EU.

"The Government asserts that the executive may use the royal prerogative to serve the notice. The court is asked to determine that issue in isolation from the politics that surround the whole question of Brexit."

Mr Dos Santos has received both support and criticism on social media leading up to the case, with some calling him "brave" and other accusing him of going against the British public's decision.

Sir Brian Leveson, president of the Queen's Bench Division, and Mr Justice Cranston will consider the case today.