- and therefore:
They are sometimes misleadingly known as the Acts of Union (Welsh: Y Deddfau Uno), but the legal short title of each Act has since 1948 been "The Laws in Wales Act". They are also often seen cited by the years they received Royal Assent, 1536 and 1543 respectively, although the official citation uses the contemporary year in which the parliamentary session began. In the case of each of these Acts this date occurred between 1 January and 25 March, adding to the ambiguity in the dating because of the use at that time of the Julian or "old style" calendar and observed New Year's Day on 25 March rather than 1 January.
From the conquest of Gwynedd in 1282–83 until the passing of the Laws in Wales Acts, the administrative system of Wales had remained unchanged. By the Statute of Rhuddlan in 1284 the territory of the native Welsh rulers had been broken up into the five counties of Anglesey, Caernarfon, Cardigan, Carmarthen, and Merioneth. Even though the five counties were subject to English criminal law, the "Principality" was the king of England's own personal fief and Welsh law continued to be used for civil cases. The rest of Wales, except for the county of Flint, which was part of the Principality, and the Royal lordships of Glamorgan and Pembroke, was made up of numerous small lordships, each with its own courts, laws and other customs.