A UK law firm has launched a legal challenge to ensure the process for Britain leaving the European Union does not begin without a parliamentary debate and a vote.
Lawyers at Mishcon de Reya claim the Government cannot trigger Article 50 without an act of Parliament.
The case is being brought on behalf of a "group of clients" and the firm said it has been in correspondence with lawyers for the UK government since June 27th.
In order for Britain to leave the European Union, the Government must invoke Article 50. The UK then has two years to negotiate the terms of exiting the bloc.
Mishcon de Reya argues that while the result of the Referendum is not "in doubt", the outcome is not "legally binding" and it would be "unlawful" for the current or future prime minister to invoke Article 50 without parliamentary approval.
A partner at the firm Kasra Nouroozi said: "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 circumstances.
"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.
"Everyone in Britain needs the Government to apply the correct constitutional process and allow Parliament to fulfil its democratic duty which is to take into account the results of the referendum along with other factors and make the ultimate decision.
"The result of the Referendum is not in doubt, but we need a process that follows UK law to enact it. 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."