The UKSC has spoken. And as many had expected (perhaps in their more sanguine moments even the Government legal team) it has upheld the decision of the High Court that legislation is required prior to the triggering of Article 50 TEU. The judgement should become compulsory reading in Constitutional Law, especially because it sets out clearly the separation of powers between the government and parliament, in particular the law making powers of each and most significantly the reach of those laws made using institution specific law-making powers.
The UKSC remind that the basis of the prerogative power asserted by the government is in the principle of dualism – that international law and domestic law operate in independent spheres . Thus although treaties signed under international law are binding on the UK in international law, such treaties are not part of UK law and give rise to no legal rights or obligations in domestic law. Therefore just as treaties made by Ministers are not governed by domestic law, domestic law made to give national effect to those treaties cannot be governed by Ministers. As put in JH Rayner by Lord Oliver of Aylmerton:
“As a matter of the constitutional law of the United Kingdom, the Royal Prerogative, whilst it embraces the making of treaties, does not extend to altering the law or conferring rights upon individuals or depriving individuals of rights which they enjoy in domestic law without the intervention of Parliament. Treaties, as it is sometimes expressed, are not self-executing. Quite simply, a treaty is not part of English law unless and until it has been incorporated into the law by legislation…” .
Hence, as put by the UKSC ‘…the dualist system is a necessary corollary of Parliamentary sovereignty, or, to put the point another way, it exists to protect Parliament not ministers’ . In coming to this conclusion the UKSC should be seen not as ‘enemies of the people’ but on the contrary their friends: by protecting parliament, they also protect the people, ensuring that governments do not undermine the citizenry by imposing decisions upon them which have not been put before them or their representatives (ie Parliament). This may be of especial resonance to the 28% who did not use their vote in the EU referendum.
The ECA 1972, passed by Parliament to incorporate the Treaty of Rome into domestic law, is uncontroversially described as more than an ordinary statute. This assertion of the constitutional character of the 1972 Act is not new – it was set out in Thoburn and R (Buckinghamshire County Council) v Secretary of State for Transport. Importantly, the Court highlights the crucial distinction in relation to its dual impact – first it provided that ‘rights, duties and rules derived from EU law should apply in the United Kingdom as part of its domestic law’ and secondly created a ‘new constitutional process for making law in the United Kingdom.’ The former is described as ‘exclusively a question of EU law’; the latter ‘exclusively a question of domestic law’ .
From here it requires only reiteration of traditional reasoning to conclude that oversight over the domestic constitutional process remains with Parliament not government. As such, Parliament can legislate to alter the domestic constitutional process, the status of EU institutions or even the status EU law. This is not constrained by the primacy of EU law, or any rule of EU law because this is a question of the domestic constitution for Parliament. Parliamentary sovereignty is in 2017 as it was in 1972 and ‘…EU law can only enjoy a status in domestic law which that principle allows. It will therefore have that status only for as long as the 1972 Act continues to apply, and that, of course, can only be a matter for Parliament’ .
Thus just as Parliament decided in the 20th century when the Treaty of Rome should have domestic impact, it is for Parliament to decide in the 21st century when that ceases to apply; then as now this remains a question for Parliament, not the Government. The Court rejects the argument asserting that the 1972 Act foresees use of prerogative powers – without prior Parliamentary authorisation – to break the constitutional legal tie made by Parliament between EU law and the UK. On the contrary, it concludes that,
“… by the 1972 Act, Parliament endorsed and gave effect to the United Kingdom’s membership of what is now the European Union under the EU Treaties in a way which is inconsistent with the future exercise by ministers of any prerogative power to withdraw from such Treaties.”
Given the long-standing principle of parliamentary sovereignty, one may again wonder why the EU referendum was necessary. The judgment can be read as adding weight to assertions that the EU referendum was a response to party political and not national interests.