In the United Kingdom, devolution (historically called home rule in Scotland, Wales and Northern Ireland) is the Parliament of the United Kingdom's statutory granting of a greater level of self-government to three countries of the United Kingdom – Scotland, Wales and Northern Ireland, and to the subdivisions of England, specifically to strategic authorities.

Law-making powers have been granted to the Scottish Parliament, the Senedd (Welsh Parliament), and the Northern Ireland Assembly, with authority exercised by their associated executive governments: the Scottish Government, Welsh Government, and Northern Ireland Executive respectively. In England, devolved powers, functions, and responsibilities have been granted to strategic authorities throughout England. There have been other proposals for devolution in England, including national devolution, regional devolution (such as to northern England or Cornwall) or failed proposals for regional assemblies. The term "devolution" initially referred to only the law-making powers awarded to Scotland, Wales and Northern Ireland, but was expanded to also include the restructuring of non-legislative powers within England.

Devolution differs from federalism in that the devolved powers of the subnational authority ultimately reside in central government, thus the state remains, de jure, a unitary state. Legislation creating devolved parliaments or assemblies can be repealed or amended by parliament in the same way as any statute, although the parliaments and assemblies in Scotland, Wales, Northern Ireland and London were supported by public referendums. Laws such as the Scotland Act 2016 and Wales Act 2017 affirmed the permanence of their devolved institutions, and any abolishment of such must be voted for in a referendum.

Legislation passed following the EU membership referendum restricts the authority of the devolved legislatures in Scotland, Wales and Northern Ireland. Examples of this include the United Kingdom Internal Market Act 2020 and the United Kingdom common framework policies which create UK wide frameworks in relation to trade in goods and services and to professional qualifications.

Northern Ireland

Northern Ireland was the first constituent of the UK to have a devolved administration. Home Rule came into effect for Northern Ireland in 1921, under the Government of Ireland Act 1920 ("Fourth Home Rule Act"). The Parliament of Northern Ireland established under that act was prorogued (the session ended) on 30 March 1972 owing to the destabilisation of Northern Ireland upon the onset of the Troubles in late 1960s. This followed escalating violence by state and paramilitary organisations following the suppression of civil rights demands by Northern Ireland Catholics.

The Northern Ireland Parliament was abolished by the Northern Ireland Constitution Act 1973, which received royal assent on 19 July 1973. A Northern Ireland Assembly was elected on 28 June 1973 and following the Sunningdale Agreement, a power-sharing Northern Ireland Executive was formed on 1 January 1974. This collapsed on 28 May 1974, due to the Ulster Workers' Council strike.

The Northern Ireland Constitutional Convention (1975–1976) and second Northern Ireland Assembly (1982–1986) were unsuccessful at restoring devolution. In the absence of devolution and power-sharing, the UK Government and Irish Government formally agreed to co-operate on security, justice and political progress in the Anglo-Irish Agreement, signed on 15 November 1985. More progress was made after the ceasefires by the Provisional IRA in 1994 and 1997.

The 1998 Belfast Agreement (also known as the Good Friday Agreement), resulted in the creation of a new Northern Ireland Assembly, intended to bring together the two communities (nationalist and unionist) to govern Northern Ireland.Jackson, Alvin (2003) Home Rule, an Irish History 1800–2000, . Additionally, renewed devolution in Northern Ireland was conditional on co-operation between the newly established Northern Ireland Executive and the Government of Ireland through a new all-Ireland body, the North/South Ministerial Council. A British–Irish Council covering the whole British Isles and a British–Irish Intergovernmental Conference (between the British and Irish Governments) were also established.

From 15 October 2002, the Northern Ireland Assembly was suspended due to a breakdown in the Northern Ireland peace process but, on 13 October 2006, the British and Irish governments announced the St Andrews Agreement, a 'road map' to restore devolution to Northern Ireland.. On 26 March 2007, Democratic Unionist Party (DUP) leader Ian Paisley met Sinn Féin leader Gerry Adams for the first time and together announced that a devolved government would be returning to Northern Ireland. The Executive was restored on 8 May 2007. Several policing and justice powers were transferred to the Assembly on 12 April 2010.

The 2007–2011 Assembly (the third since the 1998 Agreement) was dissolved on 24 March 2011 in preparation for an election to be held on Thursday 5 May 2011, this being the first Assembly since the Good Friday Agreement to complete a full term. The fifth Assembly convened in May 2016. That assembly dissolved on 26 January 2017, and an election for a reduced Assembly was held on 2 March 2017 but this did not lead to formation of a new Executive due to the collapse of power-sharing. Power-sharing collapsed in Northern Ireland due to the Renewable Heat Incentive scandal. On 11 January 2020, after having been suspended for almost three years, the parties reconvened on the basis of an agreement proposed by the Irish and UK governments. Elections were held for a seventh assembly in May 2022. Sinn Féin emerged as the largest party, followed by the Democratic Unionist Party. The newly elected assembly met for the first time on 13 May 2022 and again on 30 May. However, at both these meetings, the DUP refused to assent to the election of a speaker as part of a protest against the Northern Ireland Protocol, which meant that the assembly could not continue other business, including the appointment of a new Executive. On 3 February 2024, a new executive was formed marking the return of devolved government to Northern Ireland.

Scotland

The Acts of Union 1707 merged the Parliament of Scotland and the Parliament of England into a single Parliament of Great Britain. Ever since, individuals and organisations advocated the return of a Scottish Parliament. The drive for home rule for Scotland first took concrete shape in the 19th century, as demands for home rule in Ireland were met with similar (although not as widespread) demands in Scotland. The National Association for the Vindication of Scottish Rights was established in 1853, a body close to the Scottish Unionist Party and motivated by a desire to secure more focus on Scottish problems in response to what they felt was undue attention being focused on Ireland by the then Liberal government. In 1871, William Ewart Gladstone stated at a meeting held in Aberdeen that if Ireland was to be granted home rule, then the same should apply to Scotland. A Scottish home rule bill was presented to the Westminster Parliament in 1913 but the legislative process was interrupted by the First World War.

The demands for political change in the way in which Scotland was run changed dramatically in the 1920s when Scottish nationalists started to form various organisations. The Scots National League was formed in 1920 in favour of Scottish independence, and this movement was superseded in 1928 by the formation of the National Party of Scotland, which became the Scottish National Party (SNP) in 1934. At first the SNP sought only the establishment of a devolved Scottish assembly, but in 1942 they changed this to support all-out independence. This caused the resignation of John MacCormick from the SNP and he formed the Scottish Covenant Association. This body proved to be the biggest mover in favour of the formation of a Scottish assembly, collecting over two million signatures in the late 1940s and early 1950s and attracting support from across the political spectrum. However, without formal links to any of the political parties it withered, and devolution and the establishment of an assembly were put on the political back burner.

Harold Wilson's Labour government set up a Royal Commission on the Constitution in 1969, which reported in 1973 to Edward Heath's Conservative government. The Commission recommended the formation of a devolved Scottish assembly, but this was not implemented. Support for the SNP reached 30% in the October 1974 general election, with 11 SNP MPs being elected. In 1978 the Labour government passed the Scotland Act which legislated for the establishment of a Scottish Assembly, provided the Scots voted for such in a referendum. However, the Labour Party was bitterly divided on the subject of devolution. An amendment to the Scotland Act that had been proposed by Labour MP George Cunningham, who shortly afterwards defected to the newly formed Social Democratic Party (SDP), required 40% of the total electorate to vote in favour of an assembly. Despite officially favouring it, considerable numbers of Labour members opposed the establishment of an assembly. This division contributed to only a narrow 'Yes' majority being obtained, and the failure to reach Cunningham's 40% threshold. The 18 years of Conservative government, under Margaret Thatcher and then John Major, saw strong resistance to any proposal for devolution for Scotland, and for Wales.

In response to Conservative dominance, in 1989 the Scottish Constitutional Convention was formed encompassing the Labour Party, Liberal Democrats and the Scottish Green Party, local authorities, and sections of "civic Scotland" like Scottish Trades Union Congress, the Small Business Federation and Church of Scotland and the other major churches in Scotland. Its purpose was to devise a scheme for the formation of a devolution settlement for Scotland. The SNP decided to withdraw, as independence was not a constitutional option countenanced by the convention. The convention produced its final report in 1995. In May 1997, the Labour government of Tony Blair was elected with a promise of creating devolved institutions in Scotland. In late 1997, a referendum was held which resulted in a "yes" vote.

The newly created Scottish Parliament (as a result of the Scotland Act 1998) has powers to make primary legislation in all areas of policy which are not expressly 'reserved' for the UK Government and parliament such as national defence and international affairs. 76% of Scotland's revenue and 36% of its spending are 'reserved'. Devolution for Scotland was justified on the basis that it would make government more representative of the people of Scotland. It was argued that the population of Scotland felt detached from the Westminster government (largely because of the policies of the Conservative governments led by Margaret Thatcher and John Major). Critics however point out that the Scottish Parliament's power is on most measures surpassed by the parliaments of regions or provinces within federations, where regional and national parliaments are each sovereign within their spheres of jurisdiction.