Next week the Supreme Court of the United Kingdom will hear arguments in the most important constitutional case in modern European history. At issue is whether Prime Minister Theresa May has authority to exercise Britain’s right to exit the European Union (EU) without a vote of Parliament. The case is styled Secretary of State v. Miller.
On June 23, the British people voted narrowly but decisively to leave the European Union, a hugely controversial result opposed by most of the leadership of both political parties, the mainstream press, and younger Britons. On November 3, the British High Court of Justice somewhat unexpectedly held that the Crown—meaning the Prime Minister—lacks authority to effectuate the results of the referendum without parliamentary approval. The government has appealed that decision, both sides have filed briefs, and the case will be argued for four days, beginning on December 5.
Miller has thrown the Brexit process into confusion. No one knows what will happen if the decision is affirmed by the Supreme Court. Majorities of members of Parliament of both major parties opposed leaving the EU, and still do. To be sure, many MPs believe they have a moral obligation to carry out the expressed will of the people, and thus will vote for Brexit despite their own strong misgivings. But members of Parliament are, in constitutional principle, expected to use their own best judgment as to the good of the nation, rather than simply to vote as their constituents wish. No one knows how a final vote would shake out. To make matters more complicated, the House of Lords—always a wild card—could delay or even derail the process even if the Commons votes for Brexit.
The British Supreme Court’s decision thus has enormous practical importance. It is therefore surprising that the legal logic of the case has received so little attention. It may seem presumptuous for an American constitutional scholar to wade into the arcane waters of British constitutionalism, but the Miller opinion rests on fundamental and long-standing legal principles, susceptible to analysis and understanding even by an outsider. I believe the High Court’s decision rests on a mistake. I do not know enough about the jurisprudence of the British Supreme Court, which was formed only in 2009 and has never faced a case of this nature before, to predict whether that court will affirm or reverse. But I do think there are strong grounds for reversal.
The decision hinged on the nature of the royal prerogative. A prerogative is a power vested in the chief executive by virtue of his or her office, not requiring legislative authorization and not subject to legislative override or interference. Familiar examples from the United States Constitution are the presidential powers of veto and pardon. The prerogative powers of the British monarch were once extensive, but over the centuries Parliament has wrested many once-prerogative powers away from the Crown and made them subject to laws passed by the legislative branch. Nonetheless, some important prerogative powers remain. Miller is, in my view, the most important case about prerogative in the history of British constitutional law since the early seventeenth century.
In theory, prerogative powers are vested in the Crown, meaning Queen Elizabeth II. Indeed, the Miller opinion reads as if the question presented were whether the Queen herself has power to act. But under modern constitutional principles, the monarch acts through her ministers, who represent the majority in Parliament. In reality, prerogatives are vested in the Prime Minister, Theresa May.
Under Article 50 of the Treaty on European Union, member states like Britain have the right “to withdraw from the Union in accordance with [their] own constitutional requirements.” The question before the High Court was whether, under the unwritten British constitution, the power to exercise Britain’s Article 50 exit right is vested in the Crown (meaning the Prime Minister), or in Parliament as a whole, which would require a vote of that body. The Brexit referendum vote does not provide authority for the Prime Minister to act. As the Court held, the referendum was advisory only.
Two uncontested principles of British constitutional law frame the legal analysis. First, as stated in Miller, “the conduct of international relations and the making and unmaking of treaties on behalf of the United Kingdom are regarded as matters for the Crown in the exercise of its prerogative powers.” Control over diplomacy is an ancient and undiminished prerogative. Giving notice under Article 50 falls squarely within the scope of this foreign affairs prerogative.
The second uncontested principle is the rub: “the Crown cannot change domestic law by any exercise of its prerogative powers.” This principle, too, has venerable roots. Early modern kings—notably Henry VIII and James I—asserted the power to make law by executive decrees (called “proclamations” or “orders in council”), but James was slapped down by the great Chief Justice Edward Coke in 1610, in The Case of Proclamations. In that decision, Coke held that “the King by his proclamation or other ways cannot change any part of the common law, or statute law, or the customs of the realm.”
In tandem, these principles mean that the Crown can make or unmake treaties without Parliamentary participation, but that any implementation requiring passage of laws or appropriation of money is dependent on Parliament. When Britain joined the EU, the Crown approved the treaty, but Parliament passed the European Communities Act (ECA), which adopted European laws and regulations into British domestic law.
The Miller Court reasoned that Brexit would change domestic law because European laws and regulations would cease to apply when the United Kingdom was no longer part of the Union. With due trepidation as an outsider to British constitutional law, this strikes me as logically incorrect.
What happens if the Crown gives notice under Article 50, and Britain ceases to be a member of the European Union? This depends on an interpretation of the ECA. The key language comes from section 2(1) of the Act: “All such rights, powers, liabilities, obligations and restrictions from time to time created or arising by or under the Treaties, and all such remedies and procedures from time to time provided for by or under the Treaties, as in accordance with the Treaties are without further enactment to be given legal effect or used in the United Kingdom shall be recognised and available in law, and be enforced, allowed and followed accordingly.”
One possible reading (the more plausible, in my view) is that the rights, obligations, etc. arising “under” the Treaties are applicable in Britain only insofar as Britain is subject to the Treaties. If that is correct, there is no need for the Crown to go to Parliament in order to effectuate Brexit. The ECA already anticipates Brexit, and in the event of withdrawal from the Treaty, European law ceases to apply—not because the Crown has changed the law, but because the provisions of the law are triggered by membership in the EU.
A second possible reading is that the ECA has brought European law into force in Britain, and that it will require an Act of Parliament to repeal it. But this does not mean the Crown lacks power to give notice under Article 50. It merely means that the unmaking of the Treaty will not have full effect without passage of legislation. This is no different from any case in which a treaty calls for a change in law or the expenditure of money. Most treaties are not “self-executing,” but require implementing legislation. Merely because implementing legislation is needed does not mean the Crown cannot enter a treaty.
Moreover, the ECA expressly empowers “Her Majesty” to issue Orders in Council “for the purpose of dealing with matters arising out of or related to any such obligations or rights” under the Treaty. The exercise of exit rights under Article 50 would appear to fall within the rubric of “matters arising out of . . . obligations or rights” under the Treaty. If so, the Prime Minister can give notice under Article 50 as an exercise of delegated authority, without relying on royal prerogative.
The Miller opinion also stressed that British citizens enjoy rights of free movement throughout the European Community, and that these rights cannot be abrogated by an exercise of royal prerogative. But these rights of movement, however important, are not held by virtue of British domestic law. The Crown is not barred from exercising prerogative powers by the possibility that foreign governments may respond in ways that affect the rights of British citizens. By analogy, British citizens might lose the right to travel or do business in Spain if Britain declared war on that country—but no one denies that the Crown had the traditional prerogative power to declare war.
In short, the Crown has the prerogative to unmake treaties, including the Treaty of European Union, without consulting Parliament. This certainly will “affect” legal rights both within Britain and on the continent, but as a formal matter, it neither makes nor unmakes domestic law. Perhaps the Supreme Court will so hold. If not, we can look forward to an unprecedented season of turmoil.