By Rose Slowe LLM, Honorary Research Fellow, University of Bristol Law School. Author on EU Law and Barrister at Foundry Chambers.
Leaving the EU without a deal on 29 March 2019 is not the “legal default”, as has been repeatedly, but wrongly, asserted. It would, in fact, be in violation of the supreme law at both the domestic and supranational level, namely the UK constitution and EU Treaties (or more broadly, the General Principles of Community Law which includes ECJ jurisprudence alongside the Treaties). As such, without an Act of Parliament authorising Brexit in whatever form, the legal default is that the Article 50 notice issued will lapse, if not unilaterally revoked.
Article 50(1) of the Treaty on European Union (‘TEU’) provides that a Member State may decide to withdraw from the EU in accordance with ‘its own constitutional requirements’. The Supreme Court, the highest judicial authority responsible for interpreting our unwritten constitution, confirmed in R (on the application of Miller and another) v Secretary of State for Exiting the European Union  UKSC 5, that, as a matter of UK constitutional law, only an Act of Parliament can authorise, and give effect to, changes in domestic law and existing legal rights. The Miller litigation, while lacking in a critical respect, as discussed elsewhere, was an essential source of legal certainty in terms of our constitutional requirements and, specifically, the doctrine of parliamentary sovereignty as it pertains to Brexit; judicial clarification at the highest level of legal authority. Of significance, the majority held that the European Communities Act 1972 has rendered EU law a source of domestic law and, now that it has acquired that status, removing it, wholly or in part, is a matter on which Parliament has to legislate.
The 137 word EU (Notification of Withdrawal) Act 2017 (‘Notification Act’), enacted in response to Miller, did not satisfy this constitutional requirement as it merely permitted the Government to give notice under Article 50(2). As set out in the so-dubbed Three Knights Opinion, the only way that the Notification Act could serve as the legislative basis for the UK’s withdrawal from the EU would be if it was ‘read as an exceptionally wide enabling law, handing to the Executive power to decide which legal rights may be given away or lost through negotiations with the EU, or by leaving the EU without an agreement.’ Especially now that the Commons has voted against both the deal negotiated and withdrawal without a deal, to infer such abdication of parliamentary responsibility from the Notification Act would fly in the face of the Supreme Court’s ruling in Miller, in which paramount constitutional importance was placed upon Parliamentary sovereignty and express statutory authorisation. Such an inference would, in effect, diminish the role of Parliament in the constitutional checks and balances of powers to nothing more than writing a blank check for withdrawal at a time when there was no indication what Brexit could, or would, look like.
Indeed, at the time Notification Act was passed, it was impossible for Parliament to expressly authorise Brexit as the terms, and concomitant change to domestic law and rights that would result, was a matter for negotiation with the European Council. It follows that further statutory authorisation was always required to give legal effect to the UK’s decision to leave the EU upon conclusion of Article 50 negotiations. As the Three Knights Opinion reasons,
‘Parliamentary sovereignty and the principle of legality require Parliament expressly to authorise withdrawal from the EU on the terms agreed with the EU, or to authorise withdrawal if no acceptable terms can be agreed.’
Support for this protestation can be inferred from even the dissenting judgment of Lord Carnwath in Miller :
‘whatever the shape of the ultimate agreement, or even in default of agreement, there is no suggestion … that the process can be completed without primary legislation in some form’ (emphasis added).
In summary, it was an Act of Parliament that brought the UK into the European Union thereby giving EU law domestic effect, and so only an Act of Parliament, rather than merely a meaningful vote, can undo this as a matter of constitutional law. Therefore, the UK can leave the EU only when Parliament has legislated to approve the terms of a withdrawal agreement or to authorise withdrawal without any agreement.
Although Article 50(3) specifies that ‘The treaties shall cease to apply to the State in question… two years after the notification referred in paragraph 2’ (emphasis added), with only an option for bilateral extension of the negotiation period provided, it would be at odds with the other provisions in this Treaty Article, and indeed the EU Treaties and other General Principles of Community Law as a whole, for this to be interpreted as a foregone conclusion. Indeed, the ECJ has ruled that notice under Article 50(2) is unilaterally revocable by the withdrawing Member State, thereby adding judicial authority to the following legal analysis.
First, pursuant to Article 50(1), a decision to withdraw must be in accordance with the Member State’s constitutional requirements. However, for the reasons set out above, these requirements cannot necessarily be satisfied at the time when notice is given. Article 50(1) and (2) must therefore be read concurrently as opposed to sequentially, meaning a Member State’s constitutionally compliant decision to leave the EU does not have to be effective before notice under Article 50(2) is given. This is supported by the language of Article 50(2), namely the use of ‘intention’ and the present tense ‘which decides’, rather than ‘has decided’.
Second, it would be incompatible with the EU Treaties for Article 50 to have the effect of ejecting a Member State against its will, or contrary to its own constitutional requirements. Article 50 is a mechanism for voluntary withdrawal, not expulsion, as it is inconsistent with the fundamental principles and aims of the EU for a Member State to be expelled. Even Article 7 TEU, the most severe sanctioning mechanism the EU has at its disposal, stops short of ejecting a Member State found to be in breach of the Union’s founding values. If withdrawal would be unconstitutional at the national level, it would be inconsistent with the Treaties’ integrationist rationale, their emphasis on shared democratic values and indeed ECJ jurisprudence – an important and longstanding principle of which is that of respect for, and deference to, national constitutional traditions – for Article 50 to be interpreted so as to have an effect that is incompatible with domestic constitutional law.
The question then arises as to the consequences if the constitutional requirement of Parliament’s express statutory approval is not satisfied upon conclusion of Article 50 process. If Parliament were unwilling to pass legislation authorising the negotiated agreement or withdrawal without any agreement in place, the constitutional requirements for Brexit would not have been met. The intention expressed in the Article 50(2) notification has to be read as subject to the fulfilment of subsequent constitutional requirements, and if those conditions remain unsatisfied at the end of the Article 50 negotiation period when the terms of withdrawal, or lack thereof, are known, the conditional notification given would have to be treated as having lapsed, if not unilaterally withdrawn, because the constitutional requirements necessary to give effect to it have not been met. Article 50(3) would not automatically expel the UK as no Member State can be forced to withdraw otherwise than pursuant to a voluntary decision taken in accordance with its own constitutional requirements.
In conclusion, if the UK is unable to leave the EU in a constitutionally compliant manner by 29 March 2019, as in by an Act of Parliament, then we cannot lawfully withdraw. If an extension of time is not agreed by the EU, or as and when that extension expires, the UK’s Article 50 notice will lapse as a matter of national and supranational law, if not unilaterally withdrawn. A no-deal Brexit in the absence of parliamentary approval is, therefore, not the legal default.