Boris Johnson was swept to power as prime minister of the United Kingdom with an unassailable majority of eighty members of parliament (MPs) after the general election in December 2019. The man who was to ‘get Brexit done’ seemed in complete control of his party, the House of Commons and the country. One of the most controversial prime ministers in our history, Johnson was propelled from one cause célèbre to another. His rule exposed weaknesses in the contemporary UK constitution and how those weaknesses can be exposed by a politician determined not to be bound by conventional constraints on his office. The following tracks Johnson’s downfall and resignation and suggests areas in prime ministerial governance that need to be addressed by the incoming UK prime minister.

The EU added a dimension of overriding legality to our constitution that was judicially determined and made by an edifice constructed by law. When the lessons of Van Gend en Loos and Costa v ENEL were learned there were profound effects: not only was legislation disapplied which contravened directly enforceable EU law but injunctions could issue against a minister standing in the shoes of the Queen as an officer of the Crown when contravening EU law. Leaving the EU involved a major change in our constitution. The EU (Withdrawal) Act 2018 (EUWA) (and now see 2020 EU Withdrawal Agreement Act) was passed to ensure a smooth transition for the UK’s legal system after Brexit. This meant that all EU law (except the Charter of Fundamental Rights), together with pre-Brexit principles of interpretation of EU law (known as “general principles of law”) and the pre-Brexit case law of the Court of Justice, was converted into UK law on 31 December 2020 as “retained EU Law” (REUL). The Government intends both to prioritise reform of retained EU law in areas that will deliver “the greatest economic gain” and to give Parliament the power to define in a more precise way the relationship between retained EU law and UK law. The scope to wander from EU norms will be confined by economic and commercial realities. A pressing constitutional priority will be the challenge to Parliament to keep under scrutiny the vast delegation of legislative powers to the executive that Brexit has brought about.