Treaty - Not Treaty

How do you write a quick 'n' easy treaty to define a Brexit transition period during which the UK and the EU act "as if" everything is as it is now?

Article 50 of the Treaty on European Union says "The Treaties shall cease to apply to the State in question from the date of entry into force of the withdrawal agreement or, failing that, two years after the notification... unless the European Council, in agreement with the Member State concerned, unanimously decides to extend this period," which offers a controlled and an uncontrolled way out of the Union.

Clause 1 of the EU Withdrawal Bill, which is about to go to the House of Lords for consideration, says "The European Communities Act 1972 is repealed on exit day". The ECA incorporates EU treaties and thereby EU law into British law. The Bill goes on: "EU-derived domestic legislation, as it has effect in domestic law immediately before exit day, continues to have effect in domestic law on and after exit day". But it now has effect as British law, not EU law effective under the ECA.

Friday's letter to business leaders from the Business, Treasury and DExEU secretaries says "during the implementation period, we are clear that the UK’s and the EU’s access to one another’s markets should continue on current terms... based on the existing structure of EU rules and regulations. And for these common rules and regulations to work effectively, they will need to remain common to both parties".

"Exit day" is pencilled in on both sides as midnight (Central European Time) 29 March 2019. As can be seen from Article 50, it could be earlier if a withdrawal agreement was concluded speedily, or later by unanimous agreement, but whenever it eventually turns out to be things will have been unplugged at both ends. The treaties will have ceased to apply, so what is the legal basis for all those structures, rules and regulations? And the EU Withdrawal Bill is intended to change all the EU legislation it carries over, referring, for example, to UK bodies rather than their EU equivalents. What will make this fundamentally changed jurisdiction behave as if (to coin a phrase) Nothing Has Changed™?

It'll have to be a bit more than a piece of paper saying "You know those treaties and directives and regulations and stuff, that defined the UK-EU relationship until yesterday? Let's pretend they're still there until - say - 2021, and just ignore any problems".

The EU's guidelines for the first part of phase 2 were issued in draft last December, updated since then, and are due to be signed off by the EU General Affairs Council of ministers tomorrow, 29 January. Let's see what kind of beast the negotiations hope to produce when the press conferences finally resume.