importance to the legal systems of the UK. It does two main things. The Act repeals the European Communities Act 1972 – which is the legislation that currently gives legal authority for EU law to have effect as national law in the UK – and it preserves existing EU law by converting it into domestic law. The existing body of EU law will be frozen as of exit day and adopted as UK law. The intended effect of this is for continuity. This is a huge task, described as “a legal undertaking of a type and scale that is unique and unprecedented” by the Constitution Committee. Being a member of the European Union has had a huge impact upon UK law, altering the development of fundamental constitutional doctrines, principles and practices. It comes as no surprise that withdrawal from the EU will disturb the current constitution. Throughout this essay I will examine the impact of the Withdrawal Act on the UK constitution through it’s impact upon parliamentary sovereignty, the relationship between parliament and government, the constitutional authority of the courts and the territorial constitution. The Act ensures that EU law continues to apply in the UK by introducing the concept of ‘retained EU law’. The aim of this is to ensure legal certainty and avoid the chaos of losing EU derived law. Section 2 of the Withdrawal Act authorises EU-derived domestic legislation to continue to have effect in domestic law. Despite having effect in the UK on a free standing legislative basis, EU-derived domestic legislation is included under the heading of ‘retained EU law’. This could be viewed as an attempt to recategorise domestic law, thus impacting on our understanding of the constitution. The Lords’ Constitution Committee questioned the need for this and recommended that EU-derived domestic legislation should be removed from the category of ‘retained EU law’. The government disagreed. As a result, EU-derived domestic legislation is vulnerable to the ministerial powers contained in the act. In addition to EU-derived domestic legislation, the Act converts directly EU legislation into retained direct EU legislation. This will ensure that all EU regulations, EU decisions and EU tertiary legislation forms part of domestic law after exit. The Act extends further by preserving what is stated in Section 4 of the act. Constitutional implications of sections 3 and 4 can be seen when considering the legal status of such retained EU law. It was agreed that EU-derived domestic legislation would maintain its original status. In relation to the retained EU law set out in sections 3 and 4 of the act, the government took the view that it should not be given the status of primary or secondary legislation. Instead, retained EU legislation will be defined as either retained minor or principal EU legislation. This is