The Legislation (Wales) Act 2019 (anaw 4) (Welsh: Deddf Deddfwriaeth (Cymru) 2019) is an Act of the National Assembly for Wales, which is designed to provide guidance on how to draft and interpret primary and secondary legislation of the Assembly.

[1] In 2016, the Law Commission published its final report on the form and accessibility of the law in Wales, recommending[2] Lord Lloyd-Jones, a Justice of the Supreme Court of the United Kingdom, wrote a document supporting codification.

[4] In April 2019, the Solicitor General of England and Wales, Robert Buckland, sent the Counsel General for Wales explaining the UK Government's position that certain provisions of the bill were outside of the legislative competence of the Welsh Assembly: mainly relating to Welsh statutory instruments made under acts of the Parliament of the United Kingdom.

[5] In June 2019, the Counsel General sent the Solicitor General, Lucy Fraser a letter explaining the Welsh Government's position that the lack of an interpretation act with provisions for bilinngual statutory instruments, made by the Welsh Government under monolingual acts of the made passed by the Parliament of the United Kingdom was problematic.

[6] In August 2019, the Solicitor General, Michael Ellis, sent the Counsel General a letter reiterating the UK Government's position but explaining that the UK Government would not refer the bill to the Supreme Court.