In the weeks following the EU referendum result, a number of key constitutional questions have emerged. Central among these has been the issue of how the process of withdrawal from the EU provided by Article 50 of the Treaty on European Union (“TEU”) may be “triggered”. In particular, the debate has focussed on whether the Prime Minister may give notice under Article 50 as an exercise of prerogative power (as Mark Elliott and Kenneth Armstrong have argued), or whether Parliament must authorise the commencement of the withdrawal process (as Tom Hickman, Nick Barber and Jeff King suggest). The High Court will be asked to rule on this issue in October, meaning the debate may be of considerably more than academic significance.
The answer to this question is not clear, and there are strong arguments on both sides. Little consideration, however, has thus far been given to the special constitutional status that the European Communities Act 1972 (“ECA”) was said by Laws LJ in Thoburn v Sunderland City Council  4 All ER to possess. Although the status of Laws LJ’s comments in that case remains uncertain, if his approach is correct, it may lend considerable support to the argument for express legislative authorisation by means of an Act of Parliament.
The constitutional status of the European Communities Act 1972
In Thoburn, Laws LJ argued obiter that the ECA could not be impliedly repealed, because it belonged to a category of statutes recognised by the common law as “constitutional”.
According to Laws LJ, “a constitutional statute is one which (a) conditions the legal relationship between citizen and state in some general, overarching manner, or (b) enlarges or diminishes the scope of what we would now regard as fundamental constitutional rights”. The ECA “clearly” satisfied these conditions, along with other examples such as the Magna Carta, the Human Rights Act 1998 and the devolution legislation.
The special protection of such constitutional statutes against implied repeal “follows from the special status of constitutional rights”. As John Adenitire has noted, it is a well-established principle of the common law that fundamental rights may only be abrogated by express words to that effect in an Act of Parliament. Given this, it follows that a subsequent Act can only curtail constitutional rights conferred by an earlier statute if it does so by express words, and not through the doctrine of implied repeal. As Laws LJ put it:
“For the repeal of a constitutional Act or the abrogation of a fundamental right to be effected by statute, the court would apply this test: is it shown that the legislature’s actual – not imputed, constructive or presumed – intention was to effect the repeal or abrogation? I think the test could only be met by express words in the later statute, or words so specific that the inference of an actual determination to effect the result contended for was irresistible.”
The proposition that such constitutional statutes exist, and that they are indeed exempt from implied repeal, draws some support from the judgment of Lord Hope in the Supreme Court case of H v Lord Advocate  UKSC 24 (as Adam Perry and Farrah Ahmed explain).
Would triggering Article 50 amount to a repeal or implied repeal of the ECA?
What, then, is the relevance of this special constitutional status to the Article 50 debate? Firstly and most obviously, if it could be shown that triggering Article 50 would amount to a repeal or implied repeal of the ECA, then it would follow from the above that such action could only be taken pursuant to express words in an Act of Parliament. However, as Elliott has argued, neither triggering Article 50 nor eventually completing the process of withdrawal from the EU would expressly or impliedly repeal the ECA. Formally, the ECA exists to give effect to the obligations imposed on the UK by the EU treaties as a matter of international law “from time to time”. Invoking Article 50 and leaving the EU would result in the UK ceasing to be subject to any such international obligations, and therefore in the ECA ceasing to have anything to give effect to. It would not, however, remove the ECA from the statute book or introduce any contradictory provision into domestic law, in the manner of an implied repeal.
The rationale of Thoburn is to protect the constitutional settlement and constitutional rights
Nevertheless, the significance of Thoburn is not limited to protecting constitutional statutes against implied repeal. Laws LJ also emphasises that “the abrogation of a fundamental right” cannot be effected by implication.
It is clear that directly effective EU law confers a great many rights on individuals against the state. Some of these can be understood as “fundamental rights” in the conventional human rights sense, not least those included in the Charter. As Adenitire argues, this alone is sufficient to conclude that Article 50 cannot be invoked in the absence of an Act of Parliament, if giving notice could be considered to result in the abrogation of such rights (as will be discussed below).
However, the reasoning in Thoburn suggests that the common law also gives protection to a broader idea of the constitutional settlement between the citizen and the state, and similarly prevents this settlement from being significantly altered in the absence of express statutory authorisation.
This proposition follows most clearly from Laws LJ’s definition of a constitutional statute, and the connection drawn between constitutional statutes and constitutional rights. As above, a constitutional statute on Laws LJ’s definition is one which either conditions the general, overarching legal relationship between citizen and state; or which enlarges or diminishes the scope of fundamental rights. The former category clearly suggests the broader constitutional arrangements pursuant to which citizens are governed, while the latter refers to the narrower idea of directly enforceable human rights. However, both categories are subject to the same protection from implied repeal, which is justified on the basis that Parliament must expressly legislate for any amendment or abrogation of those rights or arrangements.
By way of example, the Scotland Act 1998 and other devolution statutes are included in Laws LJ’s suggested examples of constitutional statutes. Although the Scotland Act does confer the right to vote in Scottish Parliament elections on individuals, it seems clear that it is an example of a statute which attracts constitutional status by virtue of its definition of the conditions according to which citizens are governed, and thereby the relationship between citizen and state. Plainly, what the law is concerned to preserve is the constitutional settlement of devolution: once it has been established that the people of Scotland should be governed by a Scottish Parliament within the scope of its devolved competence, that settlement may not be significantly altered, otherwise than by the unambiguous legislative will of the sovereign Parliament.
The same reasoning applies to the ECA. As Laws LJ said in Thoburn, “[i]t may be that there has never been a statute having such profound effects on so many dimensions of our daily lives [as the ECA]”. This is not solely because EU law provides us with certain fundamental rights against the state, but because the EU represents an entire supra-national legal system, with its own capacity to legislate and its own “judicial and administrative machinery” (as Laws LJ also put it in Thoburn). By incorporating that system into UK law through the enactment of the ECA, Parliament altered the means by which citizens are governed; the relationship between the citizen and the state; and therefore the constitutional settlement of the UK. It follows that this cannot be undone by an exercise of prerogative power, or pursuant to a lesser Parliamentary endorsement in a debate or resolution: the Thoburn approach leads to the conclusion that constitutional rights and the prevailing constitutional settlement can only be substantially altered by express words in an Act of Parliament. In just the same way as express legislation would be required to undo the existing devolution arrangements, an Act of Parliament must be required to dispense with the involvement of the EU in the existing constitutional settlement.
Would triggering Article 50 abrogate EU rights?
The critical question, therefore, is whether invoking Article 50 would in fact destroy the currently existing constitutional settlement, or abrogate the constitutional rights conferred by EU law. Again, it is possible to argue that it formally would not. Giving notice under Article 50 results only in the start of the negotiation process, which, as Elliott observes, would have an uncertain outcome. It may be that the result of the process would be a replacement agreement between the UK and the EU, which would protect the relevant rights; or that at some stage, Parliament would legislate to authorise the withdrawal and the abrogation of those rights.
However, the fact that the outcome of the process is uncertain demonstrates why invoking Article 50 without a legislative mandate cannot be lawful. It is clear that if Article 50 were to be invoked and no further steps were to be taken, two years after the date of notification the UK would cease to be party to the EU treaties. At that time, EU law would cease to bind the UK state, and all directly effective provisions of EU law would cease to be enforceable in the UK courts (because the treaties would no longer require them to be given effect in the UK for the purposes of s.2 ECA). In substance and effect, this would remove the EU from any involvement in our constitution, and amount to an abrogation of rights previously enjoyed by UK citizens. This would have been caused directly and exclusively by the giving of notice under Article 50.
It is true that this outcome may be prevented by some further action being taken, such as the UK withdrawing its Article 50 notification (if that is possible) or concluding a withdrawal agreement. However, this would lead to an unusual situation, whereby the legality of the notification would depend on subsequent events. Given the well-established administrative law principle that ultra vires acts are void ab initio, this is highly unsatisfactory. Either the exercise of the prerogative to trigger Article 50 would be lawful and effective at the time, or it would be unlawful and void. The validity of the initial act cannot be altered by unpredictable subsequent events. The only consequence of invoking Article 50 that can be anticipated with any confidence is that it will, in two years’ time, result in withdrawal from the EU and EU rights being lost, and it is on the assumption that this consequence will result that the legality of the notification should be assessed.
For these reasons, if the Thoburn approach is correct, it leads to the conclusion that the Prime Minister may not invoke Article 50 unless expressly authorised to do so by an Act of Parliament. It may be politically impossible for Parliament to refuse such authorisation, in light of the referendum result, but this fact does not alter the applicable legal principles. Whether, and to what extent, the High Court addresses the implications of Thoburn for the dispute concerning the Article 50 process currently pending before it will be a matter of great interest.
Gavin Creelman, trainee solicitor, Herbert Smith Freehills LLP. The views expressed are personal, and are not intended to reflect those of Herbert Smith Freehills LLP.
(Suggested citation: G. Creelman, ‘The Relevance of Thoburn to the Article 50 “Trigger” Debate’, U.K. Const. L. Blog (6th Sept 2016) (available at https://ukconstitutionallaw.org/))