The Article 50 judgement and withdrawing from treaties

hamish

The coverage of last Thursday’s High Court judgement on Article 50 has understandably focused on its immediate consequences for the process by which the UK will leave the European Union. However, if upheld by the Supreme Court, it is also likely to have wider constitutional significance. In this post Harmish Mehta explores the implications of one part of the court’s judgement, that the Crown’s prerogative may not be used to unmake a treaty without parliament’s approval if that would change domestic law or diminish the rights of individuals. He suggests that this could mean that the government could not withdraw from the European Convention on Human Rights without parliamentary approval.

Part of the UK constitution is the judgements of its courts of law. Such judgements can have transformative and prolonged effects on UK constitutional practice.

On 3 November, the High Court (‘the court’) handed down its judgement in R (Miller) v Secretary of State for Exiting the European Union ([2016] EWHC 2768), which stated that the executive does not have power under the Crown’s prerogative to give notice pursuant to Article 50 of the Treaty on European Union (‘TEU’) for the United Kingdom to withdraw from the EU [para. 111]). The UK Supreme Court will hear the appeal against the judgement on 5-8 December.

Of course, Miller has a considerable impact on the prospects of the UK exiting the EU in the near future. However, it should not be forgotten that Miller is a judgement of wider constitutional importance. Subject to it being modified by the Supreme Court, it has the potential to shape the UK constitution beyond Brexit. This is partly the consequence of its appeal to, and development of, longstanding and far-reaching principles of constitutional law. It rivals even R (Jackson) v Attorney General ([2005] UKHL 56) in its exploration of the UK’s constitutional history and statements of apparent constitutional truisms.

In this post I will explore the implications of one part of the court’s judgement, which amounts to what I will call, for brevity alone, the ‘unmaking principle’. This principle is that the Crown’s prerogative may not be used to unmake a treaty without parliament’s approval if that would change domestic law, be it statute or common law, in any way, or diminish rights of individuals.

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