The Justiciar of North Wales was a legal office concerned with the government of the three counties in north-west Wales during the medieval period. Justiciar was a title which had been given to one of the monarch's chief ministers in both England and Scotland. Following Edward I of England's conquest of North Wales (1277–1283), the counties of Anglesey, Caernarfonshire and Merioneth were created out of the Kingdom of Gwynedd by the Statute of Rhuddlan in 1284 and placed under direct royal control. The Justiciar of North Wales was responsible for the royal administration in these counties as well as the administration of justice. English law was applied to criminal law, but in other matters Welsh law was allowed to continue.[1]