A document submitted to the Supreme Court shows that the Government will – as revealed by The Independent last week – argue the triggering of Article 50 will not directly affect the rights of British citizens.
The shift is designed to overturn the High Court’s ruling that MPs and peers must be involved at the start of Brexit because rights would irretrievably be lost at that point.
The new argument – that Britain has a “dualist” legal system – rests on the idea that international law is not applicable in the UK until it is translated into national legislation.
If the Supreme Court agrees that triggering Article 50 is purely an international action which does not directly impact on British law, it could decide that an act of Parliament is not required.
However, some legal experts are certain to argue that will also be an implicit acceptance that Article 50 – and, therefore, Brexit itself – could later be stopped, if Parliament chose to.
Last week, Lord Kerr, the former UK diplomat who wrote Article 50, insisted it could be halted, saying: “It is not irrevocable – you can change your mind while the process is going on.
“During that period, if a country were to decide actually we don't want to leave after all, everybody would be very cross about it being a waste of time.
“They might try to extract a political price but legally they couldn't insist that you leave.”
The document, quietly released at 5pm on Friday, reads: “The UK has a dualist constitutional system. Acts of the government on the international plane may sometimes have impacts, more or less direct, in domestic law.
“But treaties are not ‘self-executing’. Individual rights and obligations which they create from time to time must be allowed into domestic law by Parliament if they are to be recognised and enforced in the UK courts.”
Elsewhere in the document, the Government repeats its central argument that it does have “prerogative powers” to invoke Article 50 while bypassing Parliament.
It states: “Contrary to the conclusion of the Divisional [High] Court, it is not the case that EU rights and obligations may only be altered or removed with the prior authorisation of an act of Parliament.”
The case will be heard, over four days, from 5 December, with a decision expected at the start of January.
If, despite the new legal argument, the Government loses, it will immediately introduce a short three-line bill and ram it through the Commons in days, to try to keep Brexit on track.
Ms May repeated, in Germany on Friday, that she will trigger Article 50 by the end of March, beginning two years of formal exit talks expected to conclude with Britain leaving the EU in spring 2019.
However, on Friday the Supreme Court threw a further hurdle in the way of a smooth Brexit, when it ruled the Scottish and Welsh governments can intervene.
Edinburgh and Cardiff will be allowed to make their separate cases to the court for the right to have a say over the triggering of the Article 50 notice period.
The decision raises the possibility – albeit thought to be slim – of the Supreme Court agreeing with the SNP that the Scottish Parliament should have a veto over the Brexit strategy. That would plunge the United Kingdom into a full-blown constitutional crisis, as well as potentially sink the Prime Minister’s exit timetable completely.
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