Labour leadership hopeful Owen Smith has promised to attempt to block the triggering of formal negotiations to leave the EU until the Government offers a second referendum or calls a general election to approve its final Brexit deal.
He said that under his leadership the Labour Party would opposed triggering Article 50 until the Conservatives commited to a second public vote.
A legal challenge bid to prevent the Government from triggering Article 50 of the Lisbon Treaty without the prior authorisation of Parliament is due to be heard in the High Court in October.
Government lawyers are expected to assert that the Prime Minister can use the royal prerogative to start the process of withdrawing from the EU.
Those mounting the challenge say 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.
