Devolution in the United Kingdom in the context of Country of the United Kingdom

The Supreme Court of the United Kingdom (initialism: UKSC) is the final court of appeal for all civil cases in the United Kingdom and all criminal cases originating in England, Wales and Northern Ireland, as well as some limited criminal cases from Scotland.

As the United Kingdom's highest appellate court for these matters, it hears cases of the greatest public or constitutional importance affecting the whole population. Additionally the Supreme Court hears cases on devolution matters from Scotland, Wales and Northern Ireland. As a consequence, the court must include judges from the three distinct legal systems of the United Kingdom – England and Wales, Scotland and Northern Ireland, made up collectively of twelve Scottish, English, Welsh and Northern Irish judges.

An act of Parliament in the United Kingdom is primary legislation passed by the UK Parliament in Westminster, London.

An act of Parliament can be enforced in all four of the UK constituent countries (England, Scotland, Wales and Northern Ireland). As a result of devolution the majority of acts that are passed by Parliament increasingly only apply either to England and Wales only, or England only. Generally acts only relating to constitutional and reserved matters now apply to the whole of the United Kingdom.

Since 1922, the United Kingdom has been made up of four countries: England, Scotland, Wales (which collectively make up Great Britain) and Northern Ireland (variously described as a country, province, jurisdiction or region). The UK prime minister's website has used the phrase "countries within a country" to describe the United Kingdom.

Although the United Kingdom is a unitary sovereign state, it contains three distinct legal jurisdictions in Scotland, England and Wales, and Northern Ireland, each retaining its own legal system even after joining the UK. Since 1998, Northern Ireland, Scotland, and Wales have also gained significant autonomy through the process of devolution. The UK Parliament and UK Government deal with all reserved matters for Northern Ireland, Scotland, and Wales, but not in general matters that have been devolved to the Northern Ireland Assembly, Scottish Parliament, and Senedd. Additionally, devolution in Northern Ireland is conditional on co-operation between the Northern Ireland Executive and the Government of Ireland (see North/South Ministerial Council) and the British Government consults with the Government of Ireland to reach agreement on some non-devolved matters for Northern Ireland (see British–Irish Intergovernmental Conference). England, comprising the majority of the population and area of the United Kingdom, does not have its own devolved government, and remains fully the responsibility of the United Kingdom Parliament centralised in London. In July 2025, the council of the English county of Cornwall backed a motion calling for Cornwall to be regarded as the UK's fifth nation.

The Good Friday Agreement (GFA) or Belfast Agreement (Irish: Comhaontú Aoine an Chéasta or Comhaontú Bhéal Feirste; Ulster Scots: Guid Friday Greeance or Bilfawst Greeance) is a pair of agreements signed on 10 April (Good Friday) 1998 that ended most of the violence of the Troubles, an ethnic and national conflict in Northern Ireland since the late 1960s. It was a major development in the Northern Ireland peace process of the 1990s. It is made up of the Multi-Party Agreement between most of Northern Ireland's political parties, and the British–Irish Agreement between the British and Irish governments. Northern Ireland's present devolved system of government is based on the agreement.

Issues relating to sovereignty, governance, discrimination, military and paramilitary groups, justice and policing were central to the agreement. It restored self-government to Northern Ireland on the basis of "power sharing" and it included acceptance of the principle of consent, commitment to civil and political rights, cultural parity of esteem, police reform, paramilitary disarmament and early release of paramilitary prisoners, followed by demilitarisation. The agreement also created a number of institutions between Northern Ireland and Ireland ("North–South"), and between Ireland and the United Kingdom ("East–West").

The Greater London Authority (GLA), colloquially known by the metonym City Hall, is the devolved regional governance body of Greater London, England. It consists of two political branches: an executive Mayor (currently Sadiq Khan) and the 25-member London Assembly, which serves as a means of checks and balances on the Mayor. The authority was established in 2000, following a local referendum, and derives most of its powers from the Greater London Authority Act 1999 and the Greater London Authority Act 2007.

It is a strategic regional authority, with powers over transport, policing, economic development, and fire and emergency planning. Three functional bodies —Transport for London, the Mayor's Office for Policing and Crime, and the London Fire Commissioner— are responsible for delivery of services in these areas. The planning policies of the Mayor of London are detailed in a statutory London Plan which is regularly updated and published.

A first minister is any of a variety of leaders of government cabinets. The term literally has the same meaning as "prime minister".

In the United Kingdom, the title of first minister is used to refer to the political leader of a devolved national government, such as the devolved governments of Scotland, Wales, and Northern Ireland, or of a dependent territory.

The courts of Scotland (Scottish Gaelic: Cùirtean na h-Alba) are responsible for administration of justice in Scotland, under statutory, common law and equitable provisions within Scots law. The courts are presided over by the judiciary of Scotland, who are the various judicial office holders responsible for issuing judgments, ensuring fair trials, and deciding on sentencing. The Court of Session is the supreme civil court of Scotland, subject to appeals to the Supreme Court of the United Kingdom, and the High Court of Justiciary is the supreme criminal court, which is only subject to the authority of the Supreme Court of the United Kingdom on devolution issues and human rights compatibility issues.

The judiciary of Scotland, except the Lord Lyon King of Arms, are united under the leadership and authority of the Lord President and Lord Justice General, who is the president of the Court of Session and High Court of Justiciary. The Court of Session has the authority, under the Courts Reform (Scotland) Act 2014, to regulate civil procedure through passing subordinate legislation knows as Acts of Sederunt, and the High Court of Justiciary has the authority to regulate criminal procedure through passing Acts of Adjournal. Both Acts of Sederunt and Acts of Adjournal have the capacity to amend primary legislation where it deals with civil or criminal procedure respectively.

The Scottish Parliament (Scottish Gaelic: Pàrlamaid na h-Alba [ˈpʰaːrˠl̪ˠəmɪtʲ nə ˈhal̪ˠapə]; Scots: Scots Pairlament) is the devolved, unicameral legislature of Scotland. It is located in the Holyrood area of Edinburgh, and is frequently referred to by the metonym ''Holyrood''. It is a democratically elected body and its role is to scrutinise the Scottish Government and legislate on devolved matters that are not reserved to the Parliament of the United Kingdom.

The Scottish Parliament comprises 129 members known as Members of the Scottish Parliament (MSPs), elected for five-year terms under the regionalised form of Additional-member system (MMP): 73 MSPs represent individual geographical constituencies elected by the plurality (first-past-the-post) system, while a further 56 are returned as list members from eight additional member regions. Each region elects seven party-list MSPs. Each region elects 15 to 17 MSPs in total. The most recent general election to the Parliament was held on 6 May 2021, with the Scottish National Party winning a plurality.

The Senedd (/ˈsɛnɛð/ SEN-edh; lit. 'parliament' or 'senate'), officially known as the Welsh Parliament in English and Senedd Cymru ([ˈsɛnɛð ˈkəmrɨ]) in Welsh, is the devolved, unicameral legislature of Wales. A democratically elected body, its role is to scrutinise the Welsh Government and legislate on devolved matters that are not reserved to the Parliament of the United Kingdom. It is a bilingual institution, with both Welsh and English being the official languages of its business. From its creation in May 1999 until May 2020, the Senedd was officially known as the National Assembly for Wales (Cynulliad Cenedlaethol Cymru) and was often simply called the Welsh Assembly.

The Senedd comprises 60 members who are known as members of the Senedd (Aelodau o'r Senedd), abbreviated as "MS" (Welsh: AS). Since 2011, members are elected for a five-year term of office under an Additional-member system, in which 40 MSs represent smaller geographical divisions known as "constituencies" and are elected by first-past-the-post voting, and 20 MSs represent five "electoral regions" using the D'Hondt method of proportional representation. Typically, the largest party in the Senedd forms the Welsh Government.

In the United Kingdom, devolved matters are the areas of public policy where the Parliament of the United Kingdom has devolved its legislative power to the national legislatures of Scotland, Wales and Northern Ireland, while reserved matters and excepted matters are the areas where the UK Parliament retains exclusive power to legislate.

Devolution in the United Kingdom is regarded as the decentralisation of power from the UK Government, with powers devolved to the Scottish Parliament and Scottish Government, the Northern Ireland Assembly and Northern Ireland Executive and the Welsh Parliament and Welsh Government, in all areas except those which are reserved or excepted. Amongst the four countries of the United Kingdom, Scotland has the most extensive devolved powers controlled by the Scottish Parliament, with the Scottish Government being described as the "most powerful devolved government in the world".