Pragmaticus - Understanding the Branches of the UK Government

Understanding the Branches of the UK Government

12/04/25

THE PALACE OF WESTMINSTER, WITH PARLIAMENT HOUSED WITHIN, IMAGE: TOMMAO WANG

The branches of the British Government are separate, independent political institutions that interact in peculiar, interlinking ways within the UK’s framework of parliamentary democracy. The UK Government can be divided into three areas:

The executive (His Majesty’s (HM) Government and the cabinet),
The legislator (Parliament),
The judiciary (The Supreme Court).

The UK’s head of state, the ruling monarch - currently King Charles III - provides authority and power to the branches of government.

De Jure Head of State

In the UK, the ruling monarch serves as our de jure head of state. This means they are the legal source of power in the UK; however, in practice, this power is vested into the branches of government. The reigning monarch vests his Royal Prerogative - the powers of the Crown - in the government’s ministers (those who run government departments). Whilst the reigning monarch is the UK’s head of state, this power is delegated to the branches of the UK government, including Parliament, which has the sole power to create and unmake laws.

UK HEAD OF STATE KING CHARLES III WITH FORMER US PRESIDENT BIDEN, IMAGE: WHITE HOUSE

Parliament

Parliament is the UK’s two-chambered legislative body. The UK Head of State, the ruling monarch, vests power in Parliament, leading to parliamentary sovereignty. This refers to Parliament becoming the highest authority in the law with the exclusive capacity to pass laws. Not even the executive branch of government (HM government and the Cabinet, headed by the Prime Minister) can itself pass laws, instead requiring Parliament to do so for it as it has veto powers, that is, the ability to just say no to any piece of legislation proposed by HM Government or any individuals working within Parliament itself.

The Two Chambers - Commons & Lords

The legislative branch is divided into two sections, the two chambers of Parliament (making Parliament bicameral): the House of Commons and the House of Lords.

When referring to the House of Commons, many will use the sweeping term Parliament, however, the two Houses of Parliament are distinct, operating with different powers and roles.

The House of Commons is made up of elected Members of Parliament (MPs) who have the power to vote on legislation. The House of Lords is unelected and revises legislation but cannot veto legislation. At one point in time, the House of Lords was the more powerful of the two chambers. However, the development of democratic sentiment in Britain led to its eventual decline (see the Parliament Acts of 1911, 1949, and the Salisbury-Addison Convention), leading to its current role as a scrutiny body which attempts to improve proposed laws, whilst the House of Commons votes to pass laws into effect.

Some have suggested the House of Lords needs to be reformed further, or even abolished entirely, as it is unelected and thus undemocratic. No consensus on this debate has been reached, although some Lords reform is currently underway.

As the government cannot pass legislation, it has to go through the House of Commons to pass its desired laws. This process is typically seamless as the government is usually formed of the largest party in the Commons, meaning it has the most MPs and, thus, the most votes, often allowing it to outvote other parties and achieve desired legislation.

THE HOUSE OF COMMONS, IMAGE: UK GOVERNMENT

Parliament’s Relationship with Devolution

Parliament also devolves some of their own power to other forms. This is where Parliament willingly surrenders itself to an extent, giving powers to other institutions, knowing full well, due to its sovereignty, that it can take these powers back. For example, Scotland’s devolved powers (also known as reserve powers) cover elements such as taxation, justice and policing, housing, education, and more.

The Supreme Court has the right to pass judgements on the legality of devolved issues. Devolved powers are only given to the institutions which receive them, including the Scottish Parliament, Welsh Senedd, and Northern Ireland Assembly, on the basis that Parliament desires to delove them, and these powers can be simply revoked by an Act of Parliament or, unpratically, abolishing the devolved legislators entirely. This is because Parliament is sovereign.

An example of the Supreme Court’s judging devolutionary issues was the 2022 decision that Scotland cannot itself call an independence referendum.

THE SCOTTISH PARLIAMENT, IMAGE: COLIN

The Executive

Prime Minister

The Prime Minister (PM) is the head of government and chair of the Cabinet, which is the collection of senior ministers which make up the British government. The PM is, technically, equal to other Cabinet ministers; however, in practice, he sets the agenda of the Cabinet and often dominates its operations. This is referred to as primus inter pares - meaning the PM is first among equals in the Cabinet, highlighted by the PM's power to appoint and fire Cabinet ministers at their whim.

The Prime Minister is the head and public face of the Government, Parliament, and the wider British political system. To become PM, one is usually the leader of the largest single party in Parliament, and thus also reflects said party, effectively making the Prime Minister the face of British governance on the whole.

Hence, the role of the British PM is to head the largest parliamentary party, set the agenda of the government, manage the Cabinet, and represent the UK internationally. The current Prime Minister is Labour Leader Keir Starmer.

PRIME MINISTER KEIR STARMER, IMAGE: PRIME MINISTER'S OFFICE

The Cabinet

The Cabinet is the collection of ministers who run the government. Ministers are responsible for the duties of the government and control the departments of the government, such as the Treasury (responsible for managing government finances), the Home Office (responsible for domestic affairs), and the Foreign Office (responsible for Britain’s policy beyond the British Isles). The Cabinet is headed by the PM.

As the collection of ministers responsible for running the government, the Cabinet makes the major governmental decisions of the United Kingdom. It is the Cabinet’s role to formulate policy and make collective decisions, making Cabinet government a core principle of the UK’s political system. Cabinet meetings are policy discussions between the Prime Minister and the collection of ministers responsible for the government’s operations.

Whilst the Prime Minister controls the agenda of the Cabinet, ministers can be asked within this environment to provide their expertise on government policy, although this is subject to the whim of the Prime Minister, refelcting the principle of primus inter pares.

Some ministers are known as ‘big beasts’. These ‘beasts’ have significant influence within the party, extending their influence within the Cabinet. This often creates a tier system within the cabinet, with the Prime Minister at the summit, the ‘big beasts’ (who usually hold important governmental roles) a step below, and the rest of the Cabinet (holding more minor positions) below them. Examples of ‘big beasts’ include Gordon Brown as Chancellor (Head of the Treasury) between 1997 and 2007 and Boris Johnson as Foreign Secretary between 2016 and 2018. Both of these figures would later assume the role of PM themselves.

STARMER HEADS CABINET, IMAGE: LAUREN HURLEY

Is the UK an ‘elective dictatorship’?

Lord Halisham described the UK as an ‘elective dictatorship’, in reference to the arrangements of the Prime Minister, the Cabinet, and Parliament. The PM is (usually) the leader of the largest parliamentary party, and the PM appoints figures to the Cabinet. Thus, due to the PM's power to control who is in Cabinet, they can, by extension, control the Cabinet itself. The Cabinet has to go through Parliament to pass laws, of which the PM is the leader of the largest party (usually). Hence, the Prime Minister can control the Cabinet, and as leader, can control the largest parliamentary party, allowing the Prime Minister to wield an egregious amount of power to pass laws by controlling the institutions involved in this process.

Different Prime Ministers adopt different management styles of Cabinet, and therefore, this phenomenon applies to a differing extent for every PM. Some argue the presence of ‘big beasts’ can negate this framework, as well as dissenting MPs who don’t vote with the government on policy. Powerful PMs, such as Margaret Thatcher or Tony Blair, were more ‘elected dictators’ than some weaker or more Cabinet-orientated PMs, such as John Major or Theresa May.

The Supreme Court

The Supreme Court is a relatively new institution. Previously, Law Lords sat in the House of Lords, the unelected chamber of Parliament, and these served as the UK’s most senior judges of the law. However, the Constitutional Reform Act 2005 removed Law Lords and created a separate institution which serves as the highest judiciary body in the UK. This system is similar in some regards to the US Supreme Court, however, the UK’s legislature (Parliament) is still sovereign in the UK, and thus, the Supreme Court cannot overule it.

The Supreme Court is the UK’s senior judiciary and has the responsibility for checking the legal compatibility of Parliament's laws. The Supreme Court cannot change or strike down legislation passed by Parliament because Parliament is sovereign. However, it can pass a declaration of incompatibility when a piece of UK law contradicts another. This often takes place related to societal rights, particularly as a result of the Human Rights Act 1998, which brought the European Convention on Human Rights 1953 into UK law.

The Supreme Court can also perform judicial reviews, which is where a government department or figure is taken to court for breaking the law, failing to meet their responsibility, or acting in ultra vires (beyond the powers of the office they hold). A notable recent example was when the Supreme Court ruled the PM could not prorogue (close) Parliament simply because they were PM, after Boris Johnson attempted to do so in 2019 (see R (on the application of Miller) (Appellant) v The Prime Minister (Respondent)).

In effect, the Supreme Court checks the work of Parliament and the executive to ensure it does not contradict other UK law. It is Parliament’s responsibility to amend the law based on this, though it does not have to. In terms of judicial reviews, the Supreme Court is akin to a referee - clarifying the powers of political positions based on the ‘rulebook’ of UK Politics, the UK Constitution.