Section 2 of the European Union Act 2011 constrains the Royal Prerogative in the event of negotiated Brexit

Yesterday I submitted a formal application to be an Intervener in the Brexit Appeal at the Supreme Court.

Part of the basis on which I did so was my belief that I had identified a piece of UK Law that constrains the use of the Royal Prerogative in the event of a negotiated Brexit.

This piece of Law which, so far as I'm aware, has otherwise been overlooked is Section 2 of the European Union Act 2011.

Here is what subsection (1) of Section 2 states:

(1) A treaty which amends or replaces TEU or TFEU is not to be ratified unless—

(a) a statement relating to the treaty was laid before Parliament in accordance with section 5,

(b) the treaty is approved by Act of Parliament, and

(c) the referendum condition or the exemption condition is met.

TEU is the Treaty on European Union. TFEU is the Treaty on the Functioning of the European Union.

Any successful Brexit negotiation must reach an agreement between the United Kingdom and the European Union.

Such an international agreement is a treaty .

Such an agreement both replaces TEU and TFEU (as the basis for the relationship between the UK and the EU) and also requires that TEU and TFEU are amended (including by deletion of mention of the United Kingdom from the text of TEU and TFEU)..

So that Brexit treaty (whether a "withdrawal agreement" or a "framework agreement") triggers the need for an Act of Parliament as expressed in Subsection (1)(b).

Any treaty which involves the UK leaving the EU inescapably removes limitations on EU competences of the kind expressed in Section 4 of the European Union Act 2011.

For example, if the UK leaves the Customs Union the EU can levy tariffs on Brtish goods.

The effect of that is that at least one further Referendum is required.

So, the effect of Section 2 of the European Union Act 2011 is that an Act of Parliament and a further Referendum is required before Brexit.

The High Court in its judgement on 3rd November 2016 indicated that an Article 50 decision and notification was "irrevocable" and that it couldn't be conditional.

Since the Act of Parliament and/or the Referendum required by Section 2 of the 2011 Act might reject the withdrawal agreement, the process is conditional.

I conclude that no Article 50 "decision" presently exists.

It follows that the Government cannot lawfully send an Article 50 "notification".

I expressed my line of argument at much greater length in my application to intervene in the Supreme Court Appeal, but this post should give you an indication of my thinking on this.

If I'm right about this then Theresa May cannot lawfully send an Article 50 notification in the present circumstances.