Section 55 of the Taxation (Cross-border Trade) Act 2018 states that:

"It shall be unlawful for Her Majesty’s Government to enter into arrangements under which Northern Ireland forms part of a separate customs territory to Great Britain."

A briefing paper for that Act set out a statement from Laurence Robertson MP that the purpose of the clause was to:

"[P]rovide a guarantee that shows we value the Union and recognise the importance of strengthening it, but also acknowledge the importance and the value of our most important trading arrangement, the UK internal market. Above all, it would contribute to upholding the constitutional integrity of the United Kingdom and safeguard the Union for the future."

I believe that the proposed Withdrawal Agreement - which contains special customs arrangements for Northern Ireland - is contrary to section 55. Unless and until Section 55 is repealed by the UK Parliament it is simply not open, as a matter of law, for the United Kingdom to enter into such an agreement.

I intend to launch an immediate petition for an injunction in the Court of Session preventing the Government from placing the Withdrawal Agreement before Parliament for approval. We expect that petition to be lodged tomorrow and heard on Friday.

The legal team is Aidan O'Neill QC, George Peretz QC instructed by Elaine Motion of Balfour + Manson.

90% of sums raised will be used to fund this litigation. The remaining 10% will go to support the core costs of the Good Law Project. Jo Maugham QC will not take a single penny from the crowdfunding.