Retained EU law in the context of "European Communities Act 1972 (UK)"

The European Union (Withdrawal) Act 2018 (c. 16) is an act of the Parliament of the United Kingdom to repeal the European Communities Act 1972, and for parliamentary approval to be required for any withdrawal agreement negotiated between the Government of the United Kingdom and the European Union. Initially proposed as the Great Repeal Bill, its passage through both Houses of Parliament was completed on 20 June 2018 and it became law by Royal Assent on 26 June.

The act is to enable "cutting off the source of EU law in the UK ... and remove the competence of EU institutions to legislate for the UK". The 2017–2019 Government of Theresa May regarded it as the most significant constitutional legislation to have been passed by Parliament since the European Communities Act itself in 1972.