'This fragment is the remains of the building where Edward I held his parliament A.D. 1283, in which was passed the Statute of Rhuddlan, securing to the Principality of Wales its judicial rights and independence'
The inscription on Parliament House is likely incorrect, since no evidence has been found to suggest that a parliament was held here in 1283. It would also suggest that the conquest of Wales by Edward I was something other than a total annexation of the Country. The building has 13th and 14th century work within the fabric, a doorway and cusped ogee, but these were probably taken from the castle, and not original to the building. The Statute of Rhuddlan, as far as we can tell was delivered from the castle itself in 1284, the year after the end of the Welsh Wars of 1282-83.
The Statute itself provided the constitutional basis for the government of North Wales until 1536, with the creation of the Laws in Wales Acts, and effectively created from the conquered county of Gwynedd the new counties of Anglesey, Caernarfonshire, Flintshire and Merionethshire. This state of affairs came after the rebellion of Dafydd ap Gruffudd, the erstwhile ally of Edward against the Welsh prince’s brother, Llywelyn ap Gruffudd in the wars of 1277. The fact that Llywelyn joined in his brother's rebellion was a tragedy for a Wales ruled by the Welsh, and was probably a reluctant decision based on honour. Given that at this point, Wales was effectively run as a fiefdom of England, Llywelyn and Dafydd were seen as traitors, and while the former died in battle, Dafydd was caught, and hung, drawn and quartered at Shrewsbury, the most prominent noble to be so killed at that time.
The Statute of Rhuddlan introduced English Common Law to Wales, although certain offences were dealt with in the Welsh fashion, such as by arbitration, and from Caernarfon, rather than from England.