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The UK Supreme Court Northern Ireland Protocol Judgment: A Return to Pre-EU Membership Orthodoxy?

Oliver Garner (Bingham Centre for the Rule of Law)


The Northern Ireland Protocol has survived a domestic challenge to its legality by prominent Unionist figures. The implication for UK-EU relations is that diplomatic negotiations remain the only avenue left for securing changes to the Protocol. Constitutionally, the United Kingdom Supreme Court’s (UKSC) judgment may represent a reversion to pre-1972 orthodoxy in the rules regarding statutory interpretation as a result of Brexit.

The Background and grounds

The challenge from the claimants, including the former Northern Ireland First Ministers Arlene Foster and the late Lord David Trimble, originated in early 2021. It was dismissed at first instance in June 2021 and by the Court of Appeal in March 2022. The appellants to the UKSC presented three grounds: (1) The Northern Ireland Protocol is incompatible with Article VI of the Acts of Union 1800 because it means that citizens in the UK and in Northern Ireland do not have the “same privileges” nor are they on the “same footing” in respect of trade, and Article VI places a restriction on exercising the prerogative power to make a Treaty that has this effect; (2) The Protocol violates section 1(1) of the Northern Ireland Act 1998 (NIA) because it has resulted in a “substantial diminution” of the status of Northern Ireland without the consent of a majority of citizens; and (3) the “democratic consent” mechanism for continuation of the Protocol violates section 42 of the NIA 1998 because it allows a decision to be made by a simple majority of the Northern Ireland Assembly rather than requiring cross-community support.

The judgment

The overarching feature of the UKSC’s judgment is that the implementation of the Northern Ireland Protocol through the primary legislation of the European Union (Withdrawal Agreement) Act 2020, amending the European Union (Withdrawal) Act 2018, serves to displace earlier legislative provisions due to chronological priority. On the “trade limb” of the Article VI argument, the court notes that Section 7A(2) of the 2018 Act ensures that Protocol obligations must be “recognised and available in domestic law”, and section 7A(3) states that “every enactment must be read and has effect” subject to this obligation. As Article VI of the Acts of Union 1800 falls under the definition of “an enactment whenever passed or made”, its effect is “modified” for the period during which the Protocol applies (paras 65-67).

Similar reasoning of express modification applies to the “treaty limb” of the Article VI argument. The passing of the 2020 Act represented “the clear intention” of Parliament to authorise the UK Government to exercise the prerogative to pass the Withdrawal Agreement despite any restrictions in Article VI (paras 74-77). Regarding section 1 of the NIA 1998, the UKSC upheld the dicta in Miller that changes to the “constitutional status” of Northern Ireland do not qualify, and only decisions on whether the territory remains within the UK or joins Ireland fall under the requirements of a border poll (paras 83-85).

On the third ground, the relevant factor is that the proceedings upon which section 42 of the Northern Ireland Act 1998 bite are devolved matters, and the Protocol falls under the “excepted matter” of international relations under paragraph 3 of Schedule 2 to the NIA 1998 (paras 86-88). The 2020 Regulations that provide for the consent mechanism were held to be compatible with section 42 of the NIA 1998 because that section had already been modified by section 7A of the 2018 Act (para 107). Finally, the UKSC decided that the regulations were also within scope despite their effect of changing the “fundamental constitutional principles” contained in section 42 of NIA 1998 because the Henry VIII clause whereby they may “make any provision that could be made by an Act of Parliament” led to “no genuine doubt” about their effect (para 109).


Commentators have paid attention to the seemingly orthodox approach adopted by the UK Supreme Court. The appellants raised the argument that the Acts of Union 1800 are “constitutional statutes” and therefore cannot be modified “absent express or specific words in a later statute” (para 58). This doctrine arose from the challenge of accommodating Parliamentary Sovereignty and the primacy of EU law in the Thoburn “Metric Martyrs” case. At paragraph 66, the UKSC states that “the debate as to whether article VI created fundamental rights in relation to trade, whether the Acts of Union are statutes of a constitutional character, whether the 2018 and 2020 Acts are also statutes of a constitutional character, and as to the correct interpretative approach when considering such statutes or any fundamental rights, is academic”.

Therefore, can we observe that the removal by Brexit of the tension between two competing principles – primacy of EU law and Parliamentary Sovereignty – which gave rise to the concept of “constitutional statutes” means that UK courts will now abandon this doctrine despite its extension into areas outside EU membership? If this were the case, then there would be irony in the context that the Act of Parliament that has taken temporal priority in this case has itself created a simulacrum of primacy through the “provision for the Withdrawal Agreement, which includes the Protocol, to be given effect in domestic law and for the disapplication of inconsistent or incompatible domestic legislation where it conflicts with the Withdrawal Agreement” (para 8).

I would argue that it is too soon to jump to the conclusion that the courts have abandoned the concept of “constitutional statutes” as a functional doctrine. The dispute in the case may be regarded as an “easy case” of express disapplication; indeed, the court’s reasoning can be regarded as fitting the logic of “constitutional statutes” insofar as the “inference of an actual determination to effect the result contended for was irresistible” (Thoburn at para 63) on the basis of the blanket disapplication effects of section 7A of the 2018 Act.


The real litmus test for whether the nuancing of absolute Parliamentary Sovereignty in the UK constitution still holds may come in the harder cases that may arise in the future outside the context of post-Brexit legal issues. In particular, the placing of the Bill of Rights Bill, which would explicitly repeal the Human Rights Act 1998, into cold storage may throw up such challenges if the current government pursues a policy of chipping into specific Convention rights on an ad hoc basis, as may be the case in proposed upcoming legislation on small boats in the UK Channel.

Oliver Garner is Maurice Wohl Research Leader in European Rule of Law at the Bingham Centre for the Rule of Law, British Institute of International and Comparative Law. He holds a B.A. in Jurisprudence from the University of Oxford, and an LL.M. in Comparative, European and International Laws and a Doctorate in Laws from the European University Institute (EUI).

The views expressed in this blog reflect the position of the author and not necessarily that of the Brexit Institute Blog.

Image credit:  Pete Linforth under a Pixabay License.

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