The term that describes the United Kingdom's process of returning the delegation of authority from the central government back to the regional governments of Scotland, Wales and Northern Ireland is "D" - devolution.
Devolution grants statutory rights and powers to the regional governments. Simply put, each regional government has its own constitution and judicial system. Each region has the power to change the legislation to suit the region. Devolution is also known as decentralization. This concept is opposite to the concept of the centralization of governments.