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United Kingdom: Brexit – High Court Rules Parliamentary Consent Required

(Nov. 16, 2016) In the latest development in the United Kingdom’s path of withdrawal from membership from the European Union, the High Court of England and Wales issued a ruling on November 3, 2016, on whether the Government of the UK can invoke, without parliamentary consent, the article of the EU treaty that launches the formal exit process. (R (Miller) v Secretary of State for Exiting the European Union [2016] EWHC 2768 (Admin), Courts and Tribunals Judiciary website.) The case, which was heard during several sessions in October before the final decision was rendered on November 3, brought up many aspects of the constitutional law of the United Kingdom that are intertwined, most notably the Royal Prerogative and the principal of parliamentary sovereignty.

The Referendum

The European Union Referendum Act 2015 provided the people of the United Kingdom with the opportunity to vote to determine whether the United Kingdom should remain in or leave the European Union. The vote was held on Thursday, June 23, 2015. Voter turnout was 71.8%, with over 30 million people casting their vote. Of the votes cast, 52% were for the UK to leave the EU, and 48% voted to remain. (Alex Hunt & Brian Wheeler, Brexit: All You Need To Know About The UK Leaving The EU, BBC NEWS (Nov. 7, 2016); European Union Referendum Act 2015, LEGISLATION.GOV.UK.)

Preparing for Exit: Triggering Article 50

The UK government pledged to trigger article 50 of the Treaty of the European Union, which would mark the start of a formal two-year period of negotiations that would result in the withdrawal of the United Kingdom from the EU, in accordance with the majority vote cast in the referendum. (Lisbon Treaty, art. 50, 2008 OJ (C 115) 1, Lisbon Treaty website (last visited Nov. 9, 2016).) The Prime Minister, Theresa May, had announced her intention to launch the formal proceedings to exit the EU by the end of March 2017. (Brexit: Theresa May to Trigger Article 50 by End of March, BBC NEWS (Oct. 2, 2016).)

During the government’s preparations for exit negotiations and prior to the formal triggering of article 50, a case was brought in the High Court arguing that the government was acting outside of its powers and could not use the Royal Prerogative to invoke article 50 without the consent of Parliament. (R (Miller) v Secretary of State.) The plaintiffs’ claimed that parliamentary approval is necessary before notice can be given under article 50, as leaving the European Union will overturn an act of Parliament and remove rights provided to the people; doing so without parliamentary consent, they argued, would be contrary to the principle that Parliament is sovereign. (Id. ¶ 4.) The government argued that Parliament could not divest the executive of its prerogative to act in international affairs.  (Id.)

Prerogative Power  

A.V. Dicey, a prominent legal scholar, defines prerogative powers as “[t]he residue of discretionary or arbitrary authority, which at any given time is legally left in the hands of the Crown.” (A. V. DICEY, INTRODUCTION TO THE STUDY OF THE LAW OF THE CONSTITUTION 424 (10th ed. 1959).) Both the concept and the scope of the Royal Prerogative are

notoriously difficult to determine. It is clear that the existence and extent of the power is a matter of common law, making the courts the final arbiter of whether or not a particular type of prerogative power exists … . The difficulty is that there are many prerogative powers for which there is no recent judicial authority and sometimes no judicial authority at all. In such circumstances, the Government, Parliament and the wider public are left relying on statements of previous Government practice and legal textbooks, the most comprehensive of which is now nearly 200 years old. (Secretary of State for Justice and Lord Chancellor, The Governance of Britain, Cm 7170 (July 2007), referring to JOSEPH CHITTY, A TREATISE ON THE LAW OF THE PREROGATIVES OF THE CROWN (1820); see also Lucinda Maer & Oonagh Gay, The Royal Prerogative, House of Commons Standard Note, SN/PC/03861 (Dec. 30, 2009).)

The Royal Prerogative includes conducting foreign relations and entering into agreements with foreign states that “acquire rights or incur liabilities on behalf of the community at large.” This is exercised on the advice of the Secretary of State for Foreign and Commonwealth Affairs, a member of the Executive, who consults with other government departments that will become involved in implementing the various parts of the treaty. (SIR WILLIAM R. ANSON, THE LAW AND CUSTOM OF THE CONSTITUTION, 131 Pt. II, Vol. II (4th ed. 1935); R v Earl of Danby, 2 Show 335 (1685); HOUSE OF COMMONS, SECOND REPORT: PARLIAMENTARY SCRUTINY OF TREATIES, 1999-2000, HC 210, Parliament website.)

The Secretary of State argued that Parliament has not expressly legislated to reduce or remove the prerogative powers of the government in the conduct of international relations and that any removal of these powers would have to be done by express language in primary legislation. That the prerogative remains in the sphere of international relations gives the Secretary of State the authority to invoke article 50 of the Treaty of the European Union. (R (Miller) v Secretary of State, ¶ 31, referring to Attorney General v De Keyser’s Royal Hotel [1920] AC 508 and Secretary of State for Foreign and Commonwealth Affairs, ex p. Rees-Mogg [1994] QB 552 (DC).)

The government further argued that there was no language to remove the prerogative power of the Crown to act in international affairs and that

Parliament must be taken to have recognised that the Crown would have power to give notice under Article 50 in the exercise of its prerogative to conduct international relations on the part of the United Kingdom and thereby intended that the Crown should have power to bring about the changes in domestic law. (Id. ¶ 36.)

Parliamentary Sovereignty

The plaintiffs’ argued that the implementation of the EU Treaty by Parliament’s enactment of the European Communities Act 1972 effectively divested the Crown of its prerogative powers to give notice to withdraw from the European Union under Article 50 without consulting with Parliament . (Id. ¶ 35; European Communities Act 1972, c. 68, Table of Contents, LEGISLATION.GOV.UK, The European Communities Act, which provided for legislation made by an international organization to have direct effect for the citizens of the United Kingdom, has been regarded by many as a constitutional statute with such importance that it is not subject to many of the rules that apply to legislation. (Thoburn v Sunderland City Council [2-3] QB 151 (DC) at ¶ 62 & R (Buckinghamshire County Council) v Secretary of State for Transport [2014] UKSC 3 at ¶ 44.)

The plaintiffs further argued that the while the prerogative provides the Executive with the authority to enter into and exit from treaties, the power to give domestic effect to these international agreements remains clearly with the legislative body, and legislation is necessary to implement any such agreements. It has been a long-standing constitutional principle that “a treaty is not part of English law unless and until it has been incorporated into the law by legislation.” (Rustomjee v The Queen (1876) 2 QBD 69 at ¶ 74.)

The Judgment

The Court considered that one of the “most fundamental rules of UK constitutional law [is] that Crown in Parliament is sovereign and that legislation enacted by the Crown with the consent of both Houses of Parliament is Supreme.” (Miller et al., ¶ 20.) The Court noted that the only time that Parliament has made provision for another form of superior legislation is with the European Communities Act 1972, which confers precedence on EU law. (European Communities Act 1972.)

The Court considered that the Referendum Act did not provide any specific authority for the executive to trigger article 50, and it was indicated in a briefing paper to Parliament when the legislature was considering the bill that the referendum would only serve to have an advisory effect. (Miller et al., ¶ 107; Referendum Act 2015.) Section 2 of the European Union Act 2011, amending the European Communities Act, furthermore specifically provided that any treaty to amend or replace the Treaty of the European Union must first be approved by an act of Parliament prior to ratification. (European Union Act 2011, c. 12, LEGISLATION.GOV.UK.)

The High Court ruled that “an important aspect of the fundamental principle of Parliamentary Sovereignty is that primary legislation is not subject to displacement by the Crown through the exercise of its prerogative powers.” It reiterated that the “subordination of the Crown … to law is the foundation of the rule of law in the United Kingdom.” (Miller et al., ¶¶ 25-26). The Court ruled that “the Crown cannot through the use of its prerogative powers increase or diminish or dispense with the rights of individuals or companies conferred by common law or status or change domestic law in any way without the intervention of Parliament.” (Id. ¶ 33.) The Court considered the argument of the Secretary of State that there was no legislation that specifically reduced the Crown’s prerogative powers in the realm of international relations, but cited a case from 1892 that held that “the Secretary of State cannot use the Crown’s powers in this sphere in such a way as to take away the rights of citizens.” (Walker v Baird [1892] AC 491.)

The ruling concluded that the intent of Parliament in enacting the European Communities Act 1972 was to introduce EU law “into domestic law … in such a way that this could not be undone by exercise of Crown prerogative power … . The Crown therefore has no prerogative power to effect a withdrawal from the relevant Treaties by giving notice under Article 50 of TEU.” (Miller et al., ¶ 92.) Thus, the Court held, the government does not have the ability to change domestic law through the use of its prerogative powers. The judgment did not include the appropriate declaratory relief and reserved determination of this issue for after the parties view the judgment. (Id. ¶ 110.)

The result of the judgment as it stands currently is that the government cannot trigger article 50 without a parliamentary vote on the subject.


This ruling, described in multiple news sources as being a “strong humiliation” for the Prime Minister, has complicated the government’s implementation of exit measures following the popular vote cast in the referendum. Some commentators have debated whether it will lead to the UK losing out during exit negotiations. A Spanish newspaper described the decision as showing the Prime Minister being “wrong on an issue of transcendental importance, which undermines her authority in managing negotiations with Europe’s other member states.” (Lucy Pasha-Robinson, Brexit Legal Challenge: European Media Brand High Court Ruling ‘Strong Humiliation’ for Theresa May, INDEPENDENT (London) (Nov. 4, 2016), citing Pablo Guimon, La Justicia Británica Establece que el Parlamento Debe Aprobar el ‘Brexit,’ EL PAÍS (Spain) (Nov. 4, 2016).)

Other reactions were strongly against the judiciary, with the Express newspaper claiming that that the judgment has caused “a crisis as grave as anything since the dark days when Churchill vowed we would fight them on the beaches.” (After Judges’ Brexit Block Now Your Country Really Needs You: We Must Get Out of the EU, EXPRESS (London) (Nov. 4, 2016).)

The government expressed its disappointment in the ruling, claiming that the referendum was approved by an act of Parliament, that the vote to leave was in accordance with that act of Parliament, and that it was acting in accordance with the popular vote and within the prerogative. (Pasha-Robinson, supra.)

The prospect of a possible appeal of the ruling and possible parliamentary involvement has led many to express frustration over the delay that will result; they note that it will cause “more uncertainty on the outcome and the timeline” for the UK’s exit from the European Union. (Hogan Lovells, The Article 50 Judgment – Brexit Means a Brexit Bill, LEXOLOGY (Nov. 7, 2016).)


It appears that the judgment will slow down the exit process, as it could be subjected to parliamentary scrutiny and provide Parliament with the opportunity to stop the government from triggering article 50 and leaving the European Union. While the majority of Members of Parliament were in support of remaining in the UK, it is considered unlikely that they would vote against invoking article 50, given that Brexit was the result of a popular vote. (Brexit Court Defeat for UK Government, BBC NEWS (Nov. 3, 2016).)

The government was given the right to appeal the judgment to the Supreme Court, and the case has been fast tracked and is scheduled to be heard on December 7, 2016, with a judgment expected early in the New Year. (Brexit Court Ruling Appeal Date Set for 5 December, BBC NEWS (Nov. 8, 2016).) In an unprecedented move, all 11 justices on the Court will sit on the panel hearing the case, and the Welsh and Scottish governments are applying to intervene in the government’s appeal to the Supreme Court. (Libby Brooks & Owen Bowcott, Scottish Government to Intervene in Article 50 Case, Says Sturgeon, GUARDIAN (Nov. 8, 2016).)

In the meantime, the government has announced that it is considering the possibility of introducing a bill to be considered before Parliament that would authorize the government to trigger article 50 of the Treaty of the European Union before the Supreme Court hears the case. (Michael Wilkinson & Laura Hughes, Government Could Pass a Law Paving the Way for Britain to Leave the European Union Within Weeks, TELEGRAPH (Nov. 7, 2016).)