Britain's Attorney General Jeremy Wright (File photo by AFP)
A legal challenge seeking to force British Prime Minister Theresa May to hold a vote in parliament before triggering Brexit is an attempt to “invalidate” the referendum to leave the European Union, her most senior legal adviser said.
The High Court is hearing the case, brought forward by investment banker Gina Miller and other claimants, for the second day on Monday. The lawsuit is against the government’s right to invoke Article 50 of the treaty on European Union (TEU) without parliamentary approval.
The legal challenge was launched after the June 23 referendum, which saw 52 percent of British citizens voting to leave the EU.  
Article 50 stipulates that any member state may leave the EU “in accordance with its own constitutional requirements.” However, both sides have offered rival interpretations of the term.
Lawyers representing the claimants argued Friday that the prime minister’s attempt to trigger the exit without a vote in parliament would amount to an unconstitutional power grab.
They told the three-judge panel that the government lacks legal authority to use the royal prerogative to notify Brussels that Britain is withdrawing under Article 50 and begin the process of ending EU law's primacy in the UK.
British Prime Minister Theresa May (L) walks out of the Foreign and Commonwealth Office (FCO) in central London on October 14, 2016. (Photo by AFP)
Attorney General Jeremy Wright told the court Monday that the legal challenge “seeks to invalidate the decision already taken to withdraw from the EU.”
“Making and unmaking treaties are an established use of royal prerogative powers. The use of prerogative powers [to trigger Brexit] was wholly within the expectation of parliament,” Wright said.
“The question is has parliament acted to limit the availability of the royal prerogative powers? The answer, we say, is no,” he added.
At the Conservative Party Conference early this month, May announced that she intended to start the formal process for Britain’s exit by the end of March 2017.
She took a swipe at those who “have still not accepted the result of the referendum,” saying “It is up to the government not to question, quibble or backslide on what we have been instructed to do, but to get on with the job.”