High Quality Content by WIKIPEDIA articles! The United Kingdom has three legal systems.English law, which applies in England and Wales, and Northern Ireland law, which applies in Northern Ireland, are based on common-law principles. Scots law, which applies in Scotland, is a pluralistic system based on civil-law principles, with common law elements dating back to the High Middle Ages. While England and Wales, Northern Ireland, and Scotland diverge in the more detailed rules of common law and equity, and while there are certain fields of legislative competence devolved in Northern Ireland, Scotland, Wales and London, there are substantive fields of law which apply across the United Kingdom.