Home Knowledge UK Government appeal rejected – Parliamentary approval required before Article 50 is triggered

UK Government appeal rejected - Parliamentary approval required before Article 50 is triggered

High Court judgment

In R (on the application of Gina Miller and Deir Tozetti Dos Santos) v Secretary for Exiting the European Union EWHC 2768 (Admin), the High Court was asked to decide whether the UK Government/the Crown has the unilateral power under Article 50 to notify the European Council of the UK’s intention to leave the EU.

Ms. Miller and Mr. Dos Santos argued that the UK Government’s proposal to serve unilateral notice under Article 50(2) violated the principle of parliamentary sovereignty.  Under this key pillar of the UK’s constitutional arrangements, the Crown is subordinate to Parliament when enacting laws which affect the rights of legal and natural persons.   Against this, the Secretary of State claimed that, unlike regarding the creation of domestic laws where Parliament is sovereign, the UK Government has the exclusive power to negotiate international agreements.  (Such power is known as the Royal prerogative.)

Finding in favour of the claimants, the High Court held that the UK Government may not use the Royal prerogative in the conduct of international relations to give notice under Article 50(2).  It rejected the Secretary of State’s argument that Parliament intended, through the European Communities Act 1972 (the “1972 Act”), that the existence of any EU rights in domestic law would be dependent on the UK’s continued membership of the EU. The Secretary of State appealed this judgment to the UK Supreme Court.

Main arguments before the Supreme Court

The Secretary of State argued that UK Government ministers are entitled to exercise the Royal prerogative regarding the EU Treaties and, thus, to give notice under Article 50(2) without prior legislation.  He also claimed that the power derived under the Royal prerogative to withdraw from the EU Treaties was not excluded by the 1972 Act. Moreover, this legislation effectively sanctioned a unilateral withdrawal by the UK Government from these treaties. The Secretary of State also argued that giving notice under Article 50(2) merely initiates the relevant negotiation process and does not, in itself, alter any UK domestic legislation.

In response, the applicants relied on the principle that international treaties cannot alter domestic law.  Giving notice under Article 50(2) would set the UK on an “irreversible course” leading to EU law ceasing, in large part, to have effect in the UK.  Such a step would inevitably alter domestic law and abrogate certain statutory rights. Doing this, without prior statutory approval, would be unlawful.

The 1972 Act – “Conduit pipe”

The Court focused on the two key functions of the 1972 Act. This statute provides that rules derived from EU law apply in the UK while also establishing a new process of making domestic legislation. While the 1972 Act gives effect to EU law, it is not the source of EU law.  Rather, it is the “conduit pipe” by which that law is introduced into national law. In addition, the primacy of EU law over UK law only exists for as long as the 1972 Act remains in force. This issue is, the Court held, solely a matter for Parliament.

The majority judgment also considered whether the 1972 Act prevents the use of the Royal prerogative to withdraw from the EU. While noting that the “conduit pipe” of EU legislation will be blocked should the UK leave the EU, the Court held that the 1972 Act precludes this happening without parliamentary approval. In this regard, the Court drew a specific distinction between changes in UK law arising from amendments to existing EU legislation and changes in UK law arising from withdrawal from the EU.

The Court noted that the key inconsistency in the Secretary of State’s argument was that he did not satisfactorily address the constitutional implications of withdrawing from the EU without parliamentary approval. Withdrawal will result in significant constitutional change which, thus, cannot be actioned by unilateral action of the UK Government. The Court therefore found that the Royal prerogative in international affairs cannot be used to block a source of law. In other words, the existence of the “conduit pipe”, as against the contents that flow through it, may only be abolished if Parliament changes the law. Moreover, the Secretary of State cannot rely on the fact that the 1972 Act does not address whether prerogative powers may be used to withdraw from the EU. The Court found that, given the domestic legal effect of such a decision, unless this legislation contains this specific provision, it cannot be read into same.

The majority thus found that due to the substance of the 1972 Act, the Royal prerogative may not be invoked by the UK Government to give notice of withdrawal under Article 50(2) without the authority of primary legislation.


The Supreme Court decided to join two cases referred from the Northern Ireland courts raising key issues regarding the devolution of powers to Stormont. (The argument that the formal approval of the Northern Ireland Assembly is required before notice of withdrawal under Article 50(2) is given was supported by both the Scottish and, interestingly, given that the majority of voters in the Principality supported ‘Brexit’, Welsh governments.)

The Court held that the Northern Ireland Act 1998 (the “1998 Act”) was passed on the premise that the UK is an EU Member State. However, this does not mean that the 1998 Act requires the UK to remain a member of the EU. Furthermore, the Court found that relations with the EU are treated no differently than other UK foreign affairs issues, i.e. they are reserved or excepted for Northern Ireland and Scotland, and are not devolved in the case of Wales. (In other words, the conduct of foreign affairs falls exclusively within the remit of the UK Government.) As a result, none of Stormont, Holyrood or Y Senned (i.e. the Welsh Assembly) are empowered to make an independent decision regarding withdrawal from the EU. In addition, none of these bodies has a power of veto on the UK’s decision to withdraw from the EU. Similarly, while the 1998 Act gave the people of Northern Ireland the right to decide whether to remain part of the UK or to become part of a united Ireland, this legislation did not require the consent of the majority of the people of Northern Ireland to any withdrawal of the UK from the EU.

The Court also examined the relationships between Westminster and Belfast, Edinburgh and Cardiff in situations where their legislative competences overlap. While in each of the relevant devolution settlements, the UK Parliament has preserved the right to legislate in devolved areas, a practice called the Sewel Convention has developed whereby the agreement of Stormont, Holyrood or Y Senned is required before Westminster legislates in areas of devolved competence. The claimants argued that, under the Sewel Convention, the relevant devolved legislature would therefore have to pass consent motions before the UK could give notice under Article 50(2). However, the Court concluded that it could not rule on this question since the Sewel Convention only creates political restraints and does not create any legally enforceable obligations. The policing of its operation thus falls outside the remit of the judiciary.

Dissenting judgments

As mentioned above, three judges, namely Lord Reed, Lord Carnwath and Lord Hughes, dissented against the majority verdict. Each judge penned a separate judgment although Lord Reed’s is easily the most detailed.

This judge considered that the terms of the 1972 Act do not prevent the UK Government from autonomously exercising its prerogative powers to give notice under Article 50(2). He considered that the 1972 Act does not impose any requirement or intention to uphold the UK’s membership of the EU.  Rather, it merely gives legal effect to rights and obligations under the EU Treaties. In other words, the 1972 Act pre-supposes and is conditional on the UK’s ongoing membership of the EU. The 1972 Act only operates and can only give legal effect to rights and obligations under the EU Treaties while the UK remains an EU Member State and thus party to the EU Treaties. As a result, if the UK leaves the EU, the 1972 Act will simply cease to apply. Therefore, the 1972 Act does not hinder the exercise of the Royal prerogative in respect of the UK’s membership of the EU.

Lord Reed also emphasised the double use of the phrase “from time to time” in Section 2(1) of the 1972 Act in reference to the rights and obligations that apply domestically under the EU Treaties. Lord Reed interpreted this provision as demonstrating that Parliament intended for the rights and obligations under the EU Treaties to be amended or repealed without the necessity of a further statute. He concluded that there is no difference between creating new laws or repealing and amending existing laws. Consequently, consent of Parliament is not required to give notice under Article 50(2).

The three dissenting judges also found that a notification under Article 50(2) does not in itself alter the application or legal effect of EU rights and obligations in the UK. A notification does nothing more than initiate the “political process of negotiation and decision-making”. Thus, legislation is not necessary.


The immediate effect of the Supreme Court’s decision is that Westminster must pass the appropriate legislation before the UK issues its Article 50(2) notice. In addition, there is no need for consent from any of the three devolved legislatures to the proposed withdrawal from the EU.

Interestingly, the Supreme Court ruled on the basis of the consensus that an Article 50(2) notice may not be given in conditional or qualified terms and that, once given, it cannot be withdrawn. Indeed, the UK Government argued that, even if this common ground was wrong, it would not make a difference to these proceedings. This is perhaps surprising given that the key factor in rejecting the Secretary of State’s appeal may have been that the inevitable effect of a withdrawal notice will be a fundamental change in the UK’s constitution.

In addition, while press reports in the immediate aftermath of the 3 November 2016 judgment suggested that the UK Government might seek to reverse its position on the issue of the irreversibility or non-conditionality of an Article 50(2) notice, this option may not have been open given that the point had been conceded before the High Court. Thus, arguing that this issue is not relevant to the ultimate outcome may well have been an attempt to divert attention from the potential tactical error made by the Secretary of State at first instance. In any event, the Supreme Court decided not to opine on whether an Article 50(2) notice is unconditional or may be withdrawn. Perhaps the Court anticipates having to address this issue for real at some point in the not too distant future?

This article was published in the Law Society Gazette in March 2017