How EU law operated as a source of English law during membership, and what remains of it now — from regulations and directives to assimilated law under the REUL Act 2023.
Nearly five decades of membership built a body of law that Brexit reordered rather than erased, and understanding the old machinery is essential to making sense of what survives. This chapter begins with the main EU instruments — regulations and directives — and how each took effect in national law, before turning to the twin pillars of supremacy and direct effect, including the conditions a provision must satisfy and the divide between vertical and horizontal effect. It then maps which instruments carry which kind of direct effect, and how indirect effect and state liability filled the gaps where direct effect ran out. Finally, it covers the preliminary reference procedure and its post-transition fate, and traces EU law's afterlife through retained EU law, its conversion to assimilated law under the REUL Act 2023, and Northern Ireland's continuing alignment under the Windsor Framework.
