Gina Miller also commended the Lords for their 'civilised and grown-up' debate
After the House of Lords voted to amend the Government’s Article 50 Bill on Thursday, Mrs Miller hinted there could be another Supreme Court case on the horizon if the Prime Minister tries to act without seeking parliamentary approval.
Asked if there is scope for another legal case if the Tory leader forces the negotiated Brexit package through the Lords, Mrs Miller told Newsnight presenter Evan Davis: “If you go back to the judgment in my case at the Supreme Court, it said that only Parliament could take away or diminish people’s rights.
That’s what’s so great about the House of Lords – they showed it could be done at a level that is civilised and grown-up and that you can respect other people’s points of view
“In 18 months time, we won’t know what rights have been taken away because we don’t know what the package will be.
“If you look at the judgment then there is some thinking that if Mrs May bypasses Parliament and doesn’t deliver on her promise, if this amendment doesn’t get in, there could be a case for us to take back to the Court to say ‘can she act on her own without Parliament?’”
Mrs Miller also praised the Upper Chamber for daring to vote against the Government on the Article 50 Bill on Tuesday.
Things you may not know about remoaner Gina Miller Thu, March 2, 2017
Gina Miller is leading the challenge that has blocked Theresa May triggering Article 50 without the consent of Parliament
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Gina Miller has won the case to block Theresa May from Article 50
She added: “It’s only right that Parliament should be involved in that process, that’s what my case was about… parliamentary sovereignty and Parliament having the right to vote and debate.
“That’s what’s so great about the House of Lords – they showed it could be done at a level that is civilised and grown-up and that you can respect other people’s points of view.”
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Gina Miller spoke to Newsnight presenter Evan Davis from Brussels
The news comes as peers chose to make their second alteration to the Article 50 Bill by supporting an amendment that requires Parliament's approval for an EU divorce deal or even for Britain to leave without any deal.
Critics have accused peers of using the amendment to create a 'veto' over the historic Brexit vote by the UK public on June 23 last year.
Peers backed the amendment with 366 voting in favour and 268 voting against.
Lord Heseltine pictured in the Lords during the Brexit Bill debate
Lord Heseltine, the Conservative Government adviser who led calls for the amendment, was sensationally sacked by Downing Street just hours after the historic Lords vote.
Responding to the news, he said: "I have just been told by the Chief Whip in the Lords that No 10 is to sack me from the five jobs with which I have been helping the Government following my vote in the House of Lords earlier today.
"This is entirely the right of the Prime Minister and I'm sorry that the expertise which I have put at the Government's disposal over the last six years has now come to an end.
"However, in the last resort, I believe, as I said in the House of Lords, the future of this country is inextricably interwoven with our European friends.
"It's the duty of Parliament to assert its sovereignty in determining the legacy we leave to new generations of young people."