The Supreme Court’s decision in the case of Miller sent shockwaves around Westminster. In a case of great constitutional importance, the court decided that the Government needs approval from Parliament before it can trigger Article 50. However, with three of the eleven justices choosing to dissent, the decision was far from unanimous. In this blog, we analyse where the two sides disagreed and help you decide whether the Supreme Court made the right call.

The key question in this case is concisely summarised in the dissenting judgment of Lord Hughes. He explains that there are two accepted constitutional rules:

  1. the Government cannot change law made by an Act of Parliament nor the common law; and
  2. the making and unmaking of treaties is a matter of foreign relations within the competence of Government.

The Miller claimants relied on the first rule to argue that a notification under article 50(2) of the Lisbon Treaty (a “Notice”) would alter domestic law and remove statutory rights. Conversely, the Secretary of State argued that by operation of the second rule, the Government has the power to unmake treaties with the EU.

What did the dissenters argue?

The main argument submitted by the dissenting justices is reasoned at length by Lord Reed, with whom Lord Carnwath and Lord Hughes agree. He argues that EU law is not a source of law in the UK, but instead derives its legal authority from a statute, namely, the European Communities Act 1972 (the “1972 Act”). The effect Parliament has given to EU law in the 1972 Act is conditional on the application of the EU treaties to the UK. Therefore, should the treaties cease to apply to the UK, the 1972 Act is not changed and no further legislation is required.

The UK takes a ‘dualist’ approach to international law. In short, this means that when the UK signs an international treaty, the rules of the treaty only take effect between states at the international level. Consequently, an Act of Parliament is required to convert the UK's international obligations into law with domestic effect. In the UK, section 2(1) of the 1972 Act gives effect to the law in EU Treaties and EU legislation. It provides that:

“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; …”

Acknowledging the density of the provision, Lord Reed expresses its essential structure in this way:

“All such [members of a specified category] as [satisfy a specified condition] shall be [dealt with in accordance with a specified requirement]”

The provision is conditional in its nature and imports no obligation in respect of the UK’s membership of the EU. It only applies if there are members of a specified category that satisfy the relevant condition. The 1972 Act merely imports the UK’s international obligations under EU law into domestic law and the nature of its drafting caters for any changes to these obligations. Consequently, if the EU treaties no longer apply to the UK, then there are no rights, powers and so forth, which are to be given legal effect in the UK. Following this logic, Lord Reed argues that when the UK withdraws from the EU, the rights conferred by EU law are revoked by the operation of the 1972 Act itself rather than the exercise of prerogative powers.

Therefore, according to the dissenters: the rule that the Government cannot change domestic law does not apply, the ability to submit a Notice falls within the executive’s competence to make or unmake treaties and no Act of Parliament is required.

How does this conflict with the majority judgment?

Whilst there were other disagreements, the competing views over the effect of the 1972 Act lay at the heart of the court’s decision. The majority judgment, drafted by Lord Neuberger, (see our blog here) reasoned that the effect of the 1972 Act is ‘to constitute EU law as an independent and overriding source of domestic law’ until Parliament decides otherwise. The majority argue that the 1972 Act goes beyond simply giving effect to EU law but introduces a process by which EU law becomes a source of UK law and can even take precedence over domestic statute. Consequently, it is unrealistic to deny that the EU treaties are direct sources of law. In reply, Lord Reed argues that this view ignores that the effect of the 1972 Act (i.e. to import EU law into UK law) is conditional on the UK’s continued membership of the EU.

Agreeing with the dissenting judgment, the majority accept that the EU law incorporated into domestic law through the 1972 Act varies with the UK’s obligations under the EU treaties. However, they argue that withdrawal is ‘fundamentally different’ both in ‘degree and kind’ from variations in the content of EU law, such as treaty changes. Lord Reed responds that there is no basis in the wording of the 1972 Act for drawing such a distinction.

Did the majority get it right?

The Supreme Court was taken on a grand tour of case law going back as far as the Case of Proclamations of 1610. However, the case law itself and the rules which it establishes (above) were largely uncontroversial. Whether you believe the Supreme Court came to the right decision largely depends on how you interpret the 1972 Act. Based on a purely textual analysis, the arguments of the dissenters may be attractive. Nevertheless, it is easy to see how the Supreme Court reached the conclusion that ‘we cannot accept that a major change to UK constitutional arrangements can be achieved by ministers alone’.