The UK will regain its sovereignty from the EU for a just "millisecond" when it splits from the economic and political bloc, according to Sir Keir Starmer.
The shadow Brexit secretary also claimed the government has interpreted Vote Leave's 'Take Control' slogan to mean "no control", as Theresa May refuses to give parliament a vote on her administration's negotiating terms with Brussels.
Starmer argued the UK would have "lots and lots" of bilateral treaties with the EU.
"We are not just going to walk away and have no relationship with them," he said.
"So we will come out of one treaty and we'll sign a whole bunch of new treaties."
"Guess what? They're treaties. So when you sign a treaty you have – for the common good – given back again that bit of your sovereignty. The sovereignty that we gain will be for a millisecond between the signature that ends the major treaty and the signatures that enter the new treaties," he said.
Starmer, a former head of the Crown Prosecution Service, also issued a warning about the government's Great Repeal Bill.
The draft legislation was announced at the Conservative Party conference in Birmingham, where David Davis explained the government would scrap the European Communities Act 1972.
The Great Repeal Bill would take its place and enshrine all EU law into UK law, allowing MPs to amend, build on or repeal legislation from Brussels.
Starmer claimed the government would put a clause in the draft legislation to allow May's administration to scrap some EU derived laws by statutory instrument, an executive order which would circumvent a vote from MPs.
"Watch this space. I predict now that there will be a mechanism in the Great Repeal Act to remove some of these rights by statutory instrument," he said.
Starmer's comments, made at the Justice human rights conference in London, come after he recently returned to Jeremy Corbyn's top team.
Starmer and Shadow Foreign Secretary Emily Thornberry have sent Davis 170 questions to answer. Their letter was published amid a row over parliament's role in triggering Article 50, the official mechanism to split from the EU.
May has vowed to press on with the process and make the move by March 2017. But the government is currently facing a challenge on the issue in England's High Court.