The Statute of Rhuddlan incorporates the Principality of Wales into England.

The Statute of Rhuddlan (12 Edw 1 cc.1–12; Welsh: Statud Rhuddlan [ˈr̥ɨðlan]), also known as the Statutes of Wales (Latin: Statuta Valliae) or as the Statute of Wales (Latin: Statutum Valliae), provided the constitutional basis for the government of the Principality of Wales from 1284 until 1536. The Statute introduced English common law to Wales, but also permitted the continuance of Welsh legal practices within the Principality. The Statute was superseded by the Laws in Wales Acts 1535 and 1542 when Henry VIII made Wales unequivocally part of the "realm of England".The statute was not an act of Parliament, but rather a royal ordinance made after careful consideration by Edward I on 3 March 1284. It takes its name from Rhuddlan Castle in Denbighshire where it was first promulgated on 19 March 1284. It was formally repealed by the Statute Law Revision Act 1887.