Arch-Remainer Jolyon Maugham QC arrives at the Court of Session in Edinburgh today
Remainers' have lost a legal challenge at Scotland's highest civil court after claiming Boris Johnson's new Brexit deal was unlawful and should not be put to a vote when MPs sit tomorrow.
A legal challenge argued the proposed deal negotiated with the EU breaches UK law by leaving Northern Ireland in a separate customs arrangement to the rest of the country.
But Government lawyers defended the deal and claimed the legal action is a 'direct and manifest interference with Parliament'.
On Friday evening, Lord Pentland rejected the campaigners' argument that the agreement was unlawful, writing in his verdict that the petition was 'of very-doubtful competency'.
The judge added: 'The orders sought would unquestionably interfere to a major extent to the proposed proceedings in Parliament.
'I cannot see that it would be right for Parliament to be invited to consider a draft treaty which the court had suspended on the basis that it was unlawful.
'It is a cardinal principle of constitutional law that the courts should not intrude on the legitimate affairs and processes of Parliament.
'I consider that it should be left to Parliament to proceed in relation to the draft withdrawal agreement in the manner and according to the procedures that Parliament considers most appropriate.'
The petition was being heard in the Court of Session in Edinburgh - Scotland's highest civil court - which previously ruled Mr Johnson's prorogation of Parliament was unlawful.
Aidan O'Neill QC, acting for the petitioners, told the court on Friday the proposed Brexit deal would mean a 'continuing regime of EU law applicable to Northern Ireland' - contrary to Section 55 of the Taxation (Cross-Border Trade) Act 2018.
The challenge has been brought before Lord Pentland at the Outer House of the Court of Session by the Good Law Project, led by arch-Remainer barrister Jolyon Maugham QC.
Mr Maugham paused to speak to pro-EU demonstrators outside the Scottish court
Jolyon Maugham QC is a remain-backing barrister and newspaper columnist who has been behind a string of legal challenges to Brexit.
He backed Gina Miller's High Court battle to force the Government to give MPs a vote on triggering Article 50 and formally triggering Brexit.
He spearheaded a campaign to try to mount a legal challenge to see if Brexit can be reversed.
He had planned to take the case to the Dublin courts but abandoned it after they signalled they would not refer it to the ECJ.
And he is also the brains behind the latest challenge for a group of British expats to try to keep all their EU rights after Brexit.
The lawyer is also an occasional columnist for the liberal, Remain-baking Guardian newspaper.
He said this would breach the Act's terms by creating different customs rules in Northern Ireland to the rest of the UK, leaving the deal void and unsuitable to be put before Parliament.
Mr O'Neill said: 'What we have before us is a void agreement that has been presented publicly and to Parliament as valid.
'The agreement which was presented yesterday is void; is of no effect as a matter of law.
'If the interim suspension is granted on the basis that the agreement as a matter of national law is void, then there's no agreement which can be laid before the House.'
The Prime Minister and European Commission President Jean-Claude Juncker on Thursday announced the two sides had come to an agreement on a Brexit withdrawal deal, ahead of a crucial EU summit in Brussels.
EU leaders then approved the deal, and MPs are expected to vote on it on Saturday.
When asked what the effect of granting the petition would be on Parliament sitting on Saturday, Mr O'Neill said it could potentially repeal the law which currently