The legislation is based on the proposals of the St David's Day Command Paper.

The bill was proposed by the Conservative Party in its manifesto for the 2015 general election.

[3][4] An amended bill was introduced into the House of Commons on 1 June 2016.

One of the most important provisions is that the Act moved Wales from a conferred matters model to a reserved matters model, which is used in Scotland under the Scotland Act 1998.

The Act gives extra powers to the National Assembly for Wales and the Welsh Government:[6] The Act recognised the National Assembly for Wales and the Welsh Government as permanent among UK's constitutional arrangements, with a referendum required before either can be abolished.