The decision of the UK Supreme Court in the Miller case put to rest an important debate about who, under British constitutional law, had the authority to issue the notice under article 50 of the Treaty for European Union, which would formally commence the withdrawal by the United Kingdom from the European Union. Because this notice would trigger a cascade of events that would lead to radical changes to UK law and ultimately to withdrawal from the European Union, it was not surprising that the court concluded that only the British Parliament through legislation, and not the executive through prerogative action, could authorize the giving of notice under article 50. Two months later, the May government succeeded in getting a hurried bill through both houses of Parliament to provide that authority, and last week Prime Minister May triggered article 50 by her letter to European Council President Donald Tusk.
As May rushes headlong to the cliff edge of Brexit, it is poignant to note that the court did not decide, but took as “common ground” between the parties, that article 50 notice was not revocable. One gathers that there may be more debate on this in the future if negotiations go badly and a sobered British populace has a change of heart. In the meantime, it is useful to consider what Canadian constitutionalism can offer to illuminate the challenges of negotiating such a momentous breakup.
Brexit apologists have too hastily dismissed relevant constitutional law, conventions and principles, putting all their stock in the slim referendum vote. In a judgment that reads like a constitutional law primer, the UK Supreme Court had to tell the May government, that is, the executive branch, that it did not have the power to change law, with or without the backing of a referendum. The court emphasized the constitutional framework, in which Crown prerogative is constrained by Parliamentary sovereignty. Thus, even though the executive could exercise Crown prerogative to negotiate, enter into and withdraw from treaties, it could not do this when it had the effect of making or unmaking domestic law, as this was Parliament’s role. Therefore, the executive could not invoke article 50 without Parliament’s authority given by enactment of a law. The significance of this constitutional principle was highlighted by the fact that article 50 notice would result in an unprecedented and massive unravelling of UK domestic law that had resulted from the European Communities Act 1972, which enabled the flow-through of EU law into UK domestic law. The court also explained that although a referendum could result in a change in law if Parliament had expressly so provided, this had not been done for the Brexit referendum. Therefore, it was only advisory and could not usurp Parliament to become a new source of law-making authority.
The judgment addressed the legal rights of the United Kingdom’s devolved parliaments in a minimalist way, with Lord Neuberger for the majority noting that the Sewell Convention on consultation “has an important role in facilitating harmonious relationships between the UK Parliament and the devolved legislatures,” and referring to a Supreme Court of Canada decision in Re Resolution to Amend the Constitution to point out that constitutional convention is not legally binding or enforceable in the courts. Guided by the SCC judgment, Lord Neuberger asserted that “it is well established that the courts of law cannot enforce a political convention.” Saying political conventions are not enforceable in the courts, however, does not mean that non-observance is without sanction. Indeed, disregard of political convention “may lead to political defeat, to loss of office, or to other political consequences” — just the kind of political turmoil stirring now in the not-so-United Kingdom.
Perhaps if the UK Supreme Court had had the luxury of more time to deliberate and had not been under such intense pressure, it might have considered another SCC decision, the 1998 Reference re Secession of Quebec (Secession Reference), which would have shed more light on the subtle complexity of making momentous constitutional change. The case offers important practical guidance for politicians, citizens, lawyers and courts contemplating how to conduct Brexit negotiations within the United Kingdom and with the rest of the European Union.
The question in the Secession Reference was whether the Province of Quebec had a right unilaterally to secede from Canada after a provincial referendum in favour of separation. Finding that the international law right of self-determination was not applicable to the people of Quebec because they enjoyed full political rights and representation in the provincial and federal governments, the court focused its attention on seeking secession in accordance with the Canadian Constitution.
The unanimous court observed that “the evolution of our constitutional arrangements has been characterized by adherence to the rule of law, respect for democratic institutions, the accommodation of minorities, insistence that governments adhere to constitutional conduct and a desire for continuity and stability.” The court identified “four foundational constitutional principles,” — “federalism, democracy, constitutionalism and the rule of law, and respect for minority rights” — that “inform and sustain the constitutional text” and “function in symbiosis” such that no one principle can “trump or exclude the operation of any other.” The court considered that it was through the complex balancing of these principles and their continuous interaction that the legitimacy of the legal and political order was produced and sustained.
The court explained that a majority vote is an important indicator of the popular will but that action in furtherance of that expression must be in accordance with the constitutional framework and the other constitutional principles of accommodation of minority rights and federalism. The court considered that a “clear repudiation by the people of Quebec of the existing constitutional order would confer legitimacy on demands for secession” and would oblige the rest of Canada “to acknowledge and respect that expression of democratic will by entering into negotiations.” In that negotiation, all parties’ conduct would be governed by the constitutional principles of “federalism, democracy, constitutionalism and the rule of law, and the protection of minorities.” This meant there were no absolute propositions. There was no legal right to unilateral secession, nor was there a legal right to ignore the results of a clear referendum vote: “Negotiations would be necessary to address the interests of the federal government, of Quebec and the other provinces, and other participants, as well as the rights of all Canadians both within and outside Quebec.” If parties did not act consistently with the underlying constitutional principles, they would put at risk the legitimacy of their exercise of rights “and the ultimate acceptance of the result by the international community.”
The lesson to be drawn from the Secession Reference to aid in understanding what’s at stake in Brexit is that constitutional principles, including democratic principles that allow voice to distinct groups within a nation, relevant political conventions, rule of law and respect for minorities, all need to be respected in negotiating Brexit. The legitimacy of the outcomes will be judged by how well negotiation processes adhere to these principles of inclusion. The May government’s early assertion that the referendum vote was all that was needed to precipitate Brexit and its denigration of the parliamentary role in leading and of the judicial role in guiding the process tend to undermine the United Kingdom’s defining historical and constitutional values. The referendum vote should be considered as a first step indicating a desire to engage in negotiation. The negotiation itself must address the full range of constitutional principles — respect for minorities, rule of law, constitutionalism and the democratic interests of distinct populations and regions. To ignore these key points would sow seeds of conflict and disintegration within the United Kingdom, as is already becoming apparent.
By analogy to the Secession Reference, the European Communities Act 1972 flow-through mechanism for continuously shaping the UK legal order can be seen as a kind of constitutional entrenchment designed to safeguard core European-UK rights and relationships by making it especially difficult to disentangle. The European Union and its citizens, including “remain” voters in the United Kingdom, are like Canada, the other provinces and the minorities within the province of Quebec in the Secession Reference. They have vested interests in the United Kingdom remaining within the European Union; they have organized their affairs confident in a future within the European Union; their families, education, careers and businesses are now in a state of existential uncertainty and fear. These are the kind of minority rights and regional considerations that need to be addressed fairly if the Brexit process is to have legitimacy. Adhering to a more inclusive negotiation process consistent with constitutional principles of democracy, rule of law and respect for minorities in internal and external Brexit negotiations would lead the United Kingdom to more stable and legitimate results.
The Secession Reference explicitly envisioned the possibility that good faith negotiations could fail to achieve satisfactory terms of separation. While the formal process under article 50 of the Treaty for European Union is quite clear, there is no guarantee that negotiations will produce the results that the United Kingdom wants. Break up can occur automatically two years after article 50 notification even if negotiations fail, but the Court in Miller did not decide that article 50 notice was necessarily irrevocable. The lesson from Canadian constitutionalism is that if the internal and external Brexit negotiations become too problematic, it may be necessary for the United Kingdom to seek an exit from Brexit through reconciliation with Europe and its own constituent populations.
 R v Miller,  UKSC 5 [Miller] (majority judgment delivered by Lord Neuberger with whom Lady Hale, Lord Mance, Lord Kerr, Lord Clarke, Lord Wilson, Lord Sumption and Lord Hodge agreed).
 Ibid at para 25.
 Ibid at para 26.
 Ibid at paras 18-19 (referring to Section 2 of the 1972 Act, headed “General Implementation of Treaties”).
 Ibid at para 151.
 Miller, supra note 2 at para 141.
 Ibid at para 142, citing Resolution to Amend, supra note 2 at 853, 882-883.
  2 SCR 217.
 Ibid at para 138.
 Ibid at para 48.
 Ibid at para 49.
 Ibid at paras 67-68.
 Ibid at para 88.
 Ibid at para 90.
 Ibid at paras 92, 103, 149.
 Ibid at para 152.