This motion, for Saturday, even if passed, will not avoid the Prime Minister having to seek an extension under the Benn Act. We will ask the Inner House on Monday to order the Prime Minister to apply to extend under the Benn Act and/or to send the letter itself. 
First (our argument today) the agreement is unlawful (section 55). Second, there is no "concluded" agreement with the EU (unlike the May deal this has not been agreed by the Council). Third, the motion will not have been debated by the Lords (section 1(1)(b) Benn Act).
It is even clearer that a Withdrawal Agreement agreed at negotiator level cannot satisfy the terms of the 2018 Withdrawal Act which is explicit that there must be "political" - which I take to mean Council rather than Commission - agreement.
This stuff is important. Parliament established a governance process to ensure it could properly scrutinise the Withdrawal Agreement. Parliament tied the hands of the Government in relation to the outcome of a trade deal.
The Prime Minister's desire to meet his short term political objective of leaving on 31 October, after three and a half years, cannot trump the need for proper scrutiny of a 500+ page document with epochal consequences for Great Britain, Northern Ireland and the EU.
The desire of the PM (elected from 160,000) to meet his short term political objective of leaving on 31 October also cannot trump the fact that our supreme Parliament (elected from 46 million) has said of a NI customs area "no".
And for our long term futures the Courts must not allow the Government to ignore a specific statutory injunction on trade policy ie not to lower food standards or not to put the NHS on the table. /ENDS
(I should note with reference to the "third" in my second tweet that the House of Lords is sitting on Saturday and *may* conclude its debate on Saturday).
(And I should note with reference to the "second" in my second tweet that the withdrawal agreement was "endorsed" yesterday at Council so that point of mine is bad. Sorry - hard when there's only one of me to keep up consilium.europa.eu/media/41087/17…).
