22. Joining, Leaving, Transitioning: The UK’s Relationship With the European Union
This chapter discusses the constitutionalization of EU law, which was led by the European Court of Justice from the 1960s using the twin principles of direct effect and supremacy. These principles were fully developed by the time the UK joined the European Community in 1973. The chapter will examine the UK’s accession process with particular reference to the European Communities Act 1972 before turning to the complex three-stage process of withdrawing from the EU. In that context, the 2016 referendum, Article 50 TEU, and the UK Supreme Court’s hearing of the English case of Miller and the Northern Irish case of McCord and Agnew, will be considered. In addition, the chapter will focus on the constitutional status of the Withdrawal Agreement, the transition period, and the constitutional importance of Northern Ireland for the current and future relationship between the UK and the EU.