As things stand, the United Kingdom will cease to be a member state of the European Union on 29 March 2019, two years after giving notice pursuant to Art 50 of the Treaty on the Functioning of the European Union (TFEU). UK businesses and nationals will lose their EU law rights in all 28 member states; non-UK EU businesses and nationals will lose their EU law rights in the UK; and the UK will cease to have rights or obligations arising out of the EU.

These fundamental legal changes will necessarily affect the relationship between the UK and the European Court of Justice (ECJ): the UK will lose its right to appoint judges to the ECJ or to be a party to cases before it; UK courts will have no power or duty to refer points of EU law to the ECJ for a preliminary ruling; and the EU Commission will have no power to bring proceedings against the UK for non-compliance with its obligations under the EU treaties.

However, the status of the ECJ as the supreme court of the EU will not be changed: it will still uphold the rule of law within the EU, and give final rulings on the validity and interpretation of EU law. It will remain the final court of appeal against decisions by the EU institutions. That was its role before the UK joined the European Communities and it will remain its role after 29 March 2019.

Moreover, the application of EU law in the UK has always been a matter for the UK courts, not for the ECJ. Although the UK courts have always accepted their obligation to enforce EU law during the period of UK membership, there is no right of appeal to the ECJ from a national court. The role of the ECJ within the UK is therefore an indirect one, based on the preliminary ruling procedure, controlled by the UK courts themselves.

Three questions therefore arise:

  • What will be the status of rulings of the ECJ in the UK courts up to and including 29 March 2019, while the UK remains a member state?
  • What will be the status of rulings of the ECJ in the UK courts after 29 March 2019?
  • What role could the ECJ play under any new arrangements between the UK and the EU that may be entered into, whether on a transitional or a permanent basis?

Interpretation of EU law after UK withdrawal

Up until 29 March 2019 (or whatever date is ultimately agreed for UK withdrawal), the position should remain as currently specified in s 3 of the European Communities Act 1972, so that UK courts remain bound by rulings on EU law by the ECJ. However, clause 6 of the European Union (Withdrawal) Bill provides that, after 29 March 2019, existing rulings of the ECJ on EU law (ie rulings given before 29 March 2019) could in principle be overridden by a contrary ruling of the Supreme Court. In respect of ECJ rulings given after 29 March 2019, the Withdrawal Bill suggests that the UK courts ‘need not [but may where appropriate] have regard to’ any ruling of the ECJ on a point of EU law, apparently including rulings relating to the period of UK membership but delivered after that date.

Whatever the politics of these provisions, they will place the UK courts in a very difficult position as a matter of law – the ECJ makes no claim to interpret national law, whether or not designed to implement EU law, so there is no question of rulings of the ECJ impinging on the powers of Parliament or the UK state to determine the content of UK law after 29 March 2019. On the other hand, the jurisdiction of the ECJ to make final determinations as to the meaning and validity of EU law is clearly established by the EU treaties and has never been questioned by Parliament or the UK courts. It is therefore difficult to see any credible basis on which a UK court might, whether before or after 29 March 2019, purport to make inconsistent rulings on points of EU law, any more than it could make rulings on points of US law that differed from valid judgments of the US Supreme Court, or rulings on the interpretation of the European Convention on Human Rights (ECHR) that differed from those of the European Court of Human Rights.

The political difficulty that arises is that the Withdrawal Bill, as a matter of practical necessity, incorporates the entire corpus of EU law into UK law, so that the meaning and application of EU law will remain of great importance to many legal issues arising before the UK courts for the indefinite future. The same political difficulty would arise if substantial elements of US law were incorporated into UK law; and such difficulties have in fact arisen since the substance of the ECHR has been introduced into UK domestic law by the Human Rights Act 1998. In each case, the problem does not depend on the relevant non-UK court continuing to make rulings on legal issues falling within its exclusive jurisdiction, but on the decision of Parliament to incorporate the relevant provisions of ‘foreign’ law into UK domestic law.

In summary, whatever the status in the UK of EU law that may ultimately be specified by Parliament, there is no sensible basis for the UK courts to differ from the ECJ as to the meaning and validity of EU law itself – the ECJ was the supreme court of the European Communities before UK accession, it has remained the supreme court of the European Union throughout UK membership, and it will retain that status under the EU treaties after UK withdrawal. It is not a matter for Parliament to amend EU law or the EU treaties conferring such status on the ECJ.

Role of the ECJ in respect of any new agreement between the UK and the other member states

The role of the ECJ under any replacement agreements between the UK and the EU is a matter for negotiation. As already noted, all the rights and obligations resulting from membership (including in particular the provisions concerning the single market and the customs union) will cease to apply on 29 March 2019 unless all 28 member states agree to the contrary.

Again, the difficulty of the situation is political rather than legal – the UK economy is facing a legal and economic precipice if the EU law rights of UK nationals and businesses in all 28 member states are abolished at a stroke by UK withdrawal on 29 March 2019. The UK is therefore seeking to persuade the other member states to allow the UK to retain the economic benefits of EU law, not only in the UK (where the Withdrawal Bill indicates the approach that the government envisages) but in all the other member states, including but not limited to Ireland and the Channel Ports.

However, there is no prospect of the other member states agreeing to maintain such rights unless the UK agrees to abide by the rules, including the established methods for the determination of legal issues arising under those rules. The position is no different in principle from the Football Association or Premier League deciding to secede from UEFA at the end of the 2019 season while seeking agreement for English clubs to continue to participate in the Champions League in future years.

The UK has proposed an alternative model, based on a form of arbitration involving both UK and EU representatives and also an independent element, as is the practice in a number of other free trade agreements between the EU and third countries. That might be a possibility were the UK to accept a much less intensive economic relationship at some point in the future, but that would itself be a highly complex and uncertain path to follow – in particular, it would almost inevitably lead to a very significant reduction in the procedural and substantive rights of UK individuals and businesses.

It is hard to see how this practical and political problem can be overcome, not only during any transitional period but also in the longer term – if the UK wishes to maintain ‘frictionless’ economic relations with the other EU member states, then it will have to do so on the basis of EU law, as developed by the ECJ since 1957.