Royal prerogative powers are the residue of powers that were once exercised personally by the monarch.

These powers are now almost entirely exercised by government ministers acting on the monarch’s behalf. They form a key element of the UK’s unwritten constitution, providing the legal basis for a range of executive actions.

While these powers are extensive, they are not unlimited. They are constrained by constitutional conventions and can be challenged in the courts. Furthermore, where a prerogative power conflicts with an act of parliament (statute law), the statute always prevails.

According to constitutional theorist A.V. Dicey, the royal prerogative can be defined as “the residue of discretionary or arbitrary authority, which at any given time is legally left in the hands of the crown”.

The key prerogative powers

The range of powers exercised under the royal prerogative are wide and remain ill-defined. As such, there is no single, codified list of prerogative powers.

The cabinet manual, published in 2011 by the Conservative-Liberal Democrat coalition government, describes and explains the operation of several of the prerogative powers.

It refers to the central prerogative power to appoint and dismiss government ministers. The cabinet manual states: “It is for the prime minister to advise the sovereign on the exercise of the royal prerogative powers in relation to government, such as the appointment, dismissal and acceptance of resignation of other ministers and certain statutory powers.”

But the manual does not, for instance, refer to the power to issue, withdraw, or refuse a British passport in the UK. This power is at the discretion of the home secretary under the royal prerogative.

The most significant prerogative powers are generally considered to cover the areas of:

Foreign affairs

This includes the power to make and ratify treaties, to recognise foreign states and to conduct diplomacy. The power to declare war and deploy the armed forces overseas is also a prerogative power. It remains the case that the decision to use military force, as a matter of law or constitutionality, does not require the prior approval of parliament.

A convention, however, has evolved that the House of Commons should be given the opportunity to debate the decision before troops are committed to combat.

There is a statutory check on the prerogative power to ratify treaties. The Constitutional Reform and Governance Act 2010 (CRAG) brought the so-called ‘Ponsonby Rule’ onto a statutory footing, requiring a 21-day period to give parliament the opportunity to scrutinise and potentially delay treaties.

Parliament

The monarch, on the advice of the prime minister, exercises the prerogative powers to summon a new parliament after a general election and to prorogue (suspend) parliament at the end of a session.

Following the passage of the Dissolution and Calling of Parliament Act 2022, which repealed the Fixed Term Parliaments Act 2011, the power to dissolve parliament ahead of an election was also returned to the royal prerogative.

The Fixed Term Parliaments Act 2011 set in legislation a default fixed election date the dissolution of a parliament and the next election. An early dissolution needed to earn the support of a “supermajority” of two-thirds of MPs. Theresa May successfully secured a two-thirds majority in parliament to call a snap general election in 2017.

The Dissolution and Calling of Parliament Act 2022 thereby revived the power of the monarch, on the advice of the prime minister, to dissolve and summon parliament.

Justice system

Ministers exercise the royal prerogative of mercy, which allows for the granting of pardons to convicted individuals. A recent example of this was the posthumous pardon given to the former scientist and father of modern computing Dr Alan Turing in December 2013 over his conviction for homosexual activity.

Under the royal prerogative, the attorney general can halt a trial on indictment by issuing a nolle prosequi. The Gordon Brown government initially proposed the abolition of this power before reconsidering.

The personal prerogatives of the monarch

A small number of prerogative powers remain the personal domain of the monarch, meaning they are not subject to the advice of ministers. However, their exercise is heavily circumscribed by convention. These include:

The appointment of a prime minister

The monarch invites the individual who is best able to command the confidence of the House of Commons to form a government. This tends to be the leader of the party with the largest number of MPs.

This power was exercised by Queen Elizabeth II in appointing Liz Truss in September 2022, and subsequently by King Charles III in appointing Rishi Sunak in October 2022, Keir Starmer in July 2024 and Andy Burnham in July 2026. Technically, the monarch also reserves the right to unilaterally dismiss a prime minister; by convention, however, any action such as this would today be seen as constitutionally outrageous and illegitimate.

The granting of royal assent

Royal assent is the final, formal step that completes a bill’s passage onto the statute books as an act of parliament.

The last time royal assent was withheld was in 1708 by Queen Anne over the Scottish Militia Bill. Even in this case, the decision was driven by the deteriorating security situation facing the recently formed Kingdom of Great Britain – as opposed to a disagreement between the sovereign and parliament.

Judicial checks on prerogative powers

GCHQ case

Since the landmark GCHQ case in 1985, the courts have assumed the right to review the exercise of prerogative powers. The 1985 case came after the prime minister, Margaret Thatcher, issued an order in council under the royal prerogative, banning employees of the Government Communications Headquarters (GCHQ) from joining any trade union for reasons of national security.

The law lords ultimately held that the order was valid. They ruled that while exercises of the royal prerogative were subject to judicial review, there were exceptions – including for matters of national security.

Article 50

In 2017, the supreme court ruled that the government could not notify the Council of the European Union of the UK’s intention to withdraw from the EU (formally triggering the process set out in Article 50 of the Treaty on European Union) under the royal prerogative.

Gina Miller, a business owner and transparency campaigner, had brought the case before the high court in 2016, arguing that the executive could not use the royal prerogative to effectively nullify previous acts of parliament relating to European integration. The government, led in court by the attorney general, Jeremy Wright, maintained that the 2016 referendum result represented a clear mandate for the executive to exercise prerogative powers.

On 24 January 2017, the supreme court ruled by a majority of eight to three that because the European Communities Act 1972 had incorporated EU law, only an act of parliament could authorise its removal. Delivering the verdict, Lord Neuberger, the president of the supreme court, said: “Withdrawal effects a fundamental change by cutting off the source of EU law, as well as changing legal rights.

“The UK’s constitutional arrangements require such changes to be clearly authorised by parliament.”

Prorogation

On 24 September 2019, the supreme court unanimously ruled that Boris Johnson’s request for Queen Elizabeth II to prorogue parliament was unlawful. Eleven justices, led by Lady Hale, ruled that the prorogation was “void and of no effect”, meaning parliament could be reconvened the following day.

The leader of the House of Commons, Jacob Rees-Mogg, had convened a meeting of privy councillors which advised the queen to prorogue parliament on 28 August 2019. The approach was denounced by critics, including those within the Conservative Party, as an anti-democratic, unconstitutional ploy to bypass MPs – at a time when the parliamentary arithmetic was finely balanced.

Prorogation in order to secure a ‘no deal’ Brexit – the default legal position under EU law’s Article 50 process – had been a point of debate in the recent Tory leadership contest.

The supreme court noted its historical role in protecting “parliamentary sovereignty from threats posed to it by the use of the prerogative powers and in doing so have demonstrated that prerogative powers are limited by the principle of parliamentary sovereignty”.

The court added: “The sovereignty of parliament would, however, be undermined as the foundational principle of our constitution if the executive could, through the use of the prerogative, prevent parliament from exercising its legislative authority for as long as it pleased.”

The Military Action Against Iraq (Parliamentary Approval) Bill

In January 1999, Labour MP Tam Dalyell introduced a bill to the House under the 10-minute rule which would require a simple majority vote in the commons to authorise any future strikes or military action.

The bill’s long title stated its objective to “require the prior approval, by a simple majority of the House of Commons, of military action by United Kingdom forces against Iraq”.

Dalyell’s bill followed Operation Desert Fox, the US-led bombing campaign intended to degrade Iraq’s ability to manufacture and use weapons of mass destruction. The four-day bombing campaign lasted from 16 to 19 December 1998.

Dalyell condemned the fact that even members of cabinet had not been consulted in the lead up to the December bombing campaign. “Britain is, after all, supposedly a parliamentary democracy, not a presidential state”, Dalyell declared.

The Labour MP stated that the real object of the bill was to try and “bring home to each MP, by vote… exactly what he or she is supporting, and the moral dilemmas… that they face”.

In this way, Dalyell said there was a “simple proposition” behind the bill.

He told the House: “In circumstances in which Britain is embarking on a protracted military operation with no clear end in sight, parliament must be formally consulted and a decision must be made by majority vote, before our country drifts into a conflict whose consequences and objectives are far from clear.”

Dalyell said before getting deeper and deeper into a “Vietnam-like conflict with Iraq, the pros and cons should have been hammered out on the anvil of parliamentary argument.”

However, the proposed legislation did not progress to second reading because it did not receive “queen’s consent”.

This is a long-established convention, distinct from royal assent, where the government must seek the monarch’s permission for parliament to debate any bill that affects the royal prerogative or the private property and interests of the crown. The bill required queen’s consent because it sought to alter the royal prerogative power relating to the decision to deploy military force.

The queen, acting on ministerial advice, did not give her consent.

Speaking before the bill’s rejection, Dalyell said: “I am not going crawling to the queen. This has nothing to do with her.”

In April 1999, Dalyell raised the rejection of his bill on a point of order. He questioned whether it was right that queen’s consent was used to block a bill regarding the rights of parliament.

The deputy speaker on duty responded: “As Erskine May on page 605 makes plain, without queen’s consent, I cannot propose the question on the second reading.”

History and evolution of the prerogative powers

Over time, the monarch’s role has evolved from that of an active political leader with a direct ability to appoint prime ministers and veto legislation to a constitutional head of state.

Since the 17th century, the monarch’s political and legislative functions, while constitutionally necessary, slowly evolved to become ceremonial duties performed on the advice of the government.

The dissolution of parliament

On 10 March 1629, King Charles I famously used his prerogative powers to dissolve parliament, beginning an 11-year period of ruling without it, known as ‘Personal Rule’. The dissolution marked a complete rupture between the king and the commons, setting a course that would ultimately lead to the English Civil War (1642-1651). Opponents came to label the period of personal rule that followed as the “11 years’ tyranny”.

The Triennial Act 1640, passed by the revolutionary Long Parliament shortly before the outbreak of civil war, mandated that parliament must convene at least once every three years, even without the king’s summons.

The Septennial Act 1715 created seven-year parliaments. The Parliament Act 1911 later amended the Septennial Act to reduce the maximum duration of a parliament from seven years to five years.

Appointing peers

The prerogative of the crown to appoint peers on the advice of the prime minister has been invoked on at least three several occasions to force contentious legislation through parliament. ‘Packing the House’ was once viewed as the only constitutional mechanism that could resolve a parliamentary stand-off between the commons and Lords.

In 1711, on the advice of the government, Queen Anne created 12 Tory peers to vote through the Treaty of Utrecht.

This was the same threat employed by Earl Grey, Whig prime minister from 1830 to 1834, to secure the passage of the Great Reform Act. In 1832, William IV reluctantly agreed to create enough new Whig peers to force the first Representation of the People Bill through the upper House. The threat alone was sufficient; under instructions from Wellington, Tory peers backed down and abstained, allowing the bill to pass.

Grey told the Lords in 1832: “I ask what would be the consequence if we were to suppose that such a prerogative [appointing peers en masse] did not exist, or could not be constitutionally exercised?

“The commons have a control over the power of the crown by the privilege, in extreme cases, of refusing supply. The crown has, by means of its power to dissolve the House of Commons, a control upon any violent and rash proceedings on the part of the commons. If a majority of this House [the Lords] is to have the power whenever they please of opposing the declared and decided wishes both of the crown and the people without any means of modifying that power, then this country is placed entirely under the influence of an uncontrollable oligarchy.”

In 1911, the prime minister, H.H Asquith, secured a commitment from King George V to pack the House of Lords with hundreds of Liberal peers if the upper chamber continued to oppose the Parliament Bill. The Conservative-dominated chamber had already vehemently objected to the bill’s central provision to abolish the veto power of the House of Lords.

Addressing the commons, Asquith declared: “A situation has been created from which there is only one constitutional way of escape, and that is unless the House of Lords will consent to restore this bill… we shall be compelled to invoke and exercise the prerogative of the crown.”

The leader of the opposition, Arthur Balfour, branded the threat to create new peers a “revolution” that would destroy the “prerogative of the crown and the independence of the upper House.”

He declared: “When such revolution has been tried, when it was actually carried in 1711, and when it was threatened in 1832, at all events, there were great causes at stake, and it seemed impossible to find any other issue from a problem on which in one case the whole interests of peace and war were on one side…

“What is the parallel now?”

Once more, however, the threat to pack the House of Lords forced peers to stand down.

The appointment of the prime minister

Political upheavals in the 1830s and 1840s helped shape the conventions governing the prerogative power of prime ministerial appointment.

In November 1834, King William IV unilaterally dismissed the Whig ministry of Lord Melbourne, William objected to the appointment of Lord John Russell as chancellor in Melbourne’s government, believing Russell to be a radical.

This marked the last time a British monarch would sack a prime minister who commanded a parliamentary majority.

The sovereign initially sent for the Duke of Wellington, who was reluctant. He said the next prime minister should sit in the commons, and therefore recommended Robert Peel to form the first Tory administration since the Great Reform Act 1832.

The formation of Peel’s second ministry in August 1841 was another significant moment in the development of this prerogative power.

Peel’s return to power began on 4 June 1841, when his motion of no confidence in the Melbourne ministry passed by a single vote (312 to 311). The subsequent election, which Melbourne’s government had already decided to call, resulted in a majority of over 70 for the Conservatives. For the first in British electoral history, the majority of the governing party (the Whigs) had been converted into a majority for the opposition party (Peel’s Conservatives).

The new parliament assembled on 19 August 1841. Melbourne, as was convention at the time, remained in office. The prime minister was selected by the sovereign, not dictated by the whims of the electorate. But the government was again defeated on a no-confidence amendment to the queen’s speech.

In the end, Melbourne had no choice but to tender his resignation to an exasperated Queen Victoria (who succeeded William as sovereign in 1837). Victoria was known to have a personally difficult relationship with Peel, and an exceptionally warm relationship with Melbourne. But in order to ensure competent government, Victoria was now obliged to send for Peel.

Peel’s assumption of power on 30 August, therefore, was the first time in British history that a prime minister had been installed primarily by a general election victory against a serving government, rather than by monarchical discretion. The Conservative victory limited Victoria’s foremost prerogative power; there could be no room for personal preference – which had so motivated the appointments made by the queen’s predecessors.

Foreign policy and the royal prerogative

On 18 March 2003, following one of the most momentous debates in modern parliamentary history, the House of Commons voted to authorise military action against Iraq. The decision gave prime minister Tony Blair the final approval to commit British forces to the imminent US-led invasion.

The 2003 vote marked the first time MPs had been given the opportunity to signify a collective position on, and issue an effective veto of, military action. Before the vote authorising military action in Iraq, governments had assumed the right to exercise the royal prerogative power to deploy troops – including ahead of the Falklands War (1982), the First Gulf War (1991), and the Kosovo War (1999).

The Iraq War vote therefore signalled the emergence of a political convention, granting parliament a veto over the deployment of troops. This precedent was effectively affirmed by David Cameron as prime minister, who held votes on military action in Libya (2011), in Syria (2013), and in Syria again (2015). Cameron’s government lost the 2013 vote, which was considered binding by the then government.

On 16 April 2018, the prime minister, Theresa May, faced MPs in the House of Commons to defend her decision to authorise military airstrikes against Syria without first seeking parliamentary consent. The action, taken in coordination with the United States and France, was a direct response to a suspected chemical weapons attack in the Syrian city of Douma on 7 April, which resulted in civilian casualties.

The decision to act without a parliamentary vote proved controversial, with opposition parties and some Conservative backbenchers arguing it ignored an emerging constitutional convention established since the 2003 Iraq War. Jeremy Corbyn, the leader of the Labour Party, accused of adhering to the “whims” of Donald Trump, who was then the US president.

The Labour leader called for a “war powers act in this country to transform a now broken convention into a legal obligation.”

A war powers act would make the historic prerogative power to pursue military action subject to parliament’s approval.

Corbyn added: “Her predecessor [David Cameron] came to this House to seek authority for military action in Libya, and in Syria in 2015, and the House had a vote on Iraq in 2003. There is no more serious issue than the life-and-death matters of military action.”

The government later won a symbolic vote on whether the House had sufficiently debated the matter of Syria by 314 to 36 votes, a majority of 278. That division came following an emergency debate forced by the Scottish National Party (SNP).

The following day, MPs considered the principle of parliament’s right to approve military action in a debate led by Corbyn. In that debate, held on 17 April, May set out her belief that the action taken did not fall within the remit of the convention on securing parliamentary approval for military action.

She argued that “there are situations – not least major deployments like the Iraq war – when the scale of the military build-up requires the movement of military assets over weeks, and when it is absolutely right and appropriate for parliament to debate military action in advance”.

But she maintained that this did not “mean that that is always appropriate.”

She added: “This therefore cannot and should not be codified into a parliamentary right to debate every possible overseas mission in advance.”

May set out “four fundamental reasons” why the strikes did not fall within the remit of the convention: effectiveness, and not wanting to compromise the safety of armed forces personnel; protecting intelligence; the imperative to work closely with allies and keeping allied plans secret; and an existing legal basis for the intervention, that of humanitarian emergency.

She asserted: “So it was right for me, as prime minister – with the full support of the cabinet, and drawing on the advice of security and military officials – to take the decision on this military strike last weekend, and for parliament to be able to hold me to account for it.”

May’s actions ultimately cast some doubt on the shape of the convention that had developed since 2003. Her decision to pursue military intervention without parliamentary approval appeared to rely on possible expectations to the convention, allowing for the government to act at speed.

In a written statement issued in 2016, the deference secretary, Michael Fallon, declared: “In observing the convention, we must ensure that the ability of our armed forces to act quickly and decisively, and to maintain the security of their operations, is not compromised.”

May explicitly cited this statement during her appearance before the commons on 16 April 2018.

Additional resources

• The Cabinet Manual (GOV.UK): https://www.gov.uk/government/publications/cabinet-manual
• House of Commons Library – The royal prerogative and ministerial advice: https://researchbriefings.files.parliament.uk/documents/CBP-9877/CBP-9877.pdf
• House of Commons Library – Prerogative Powers and the Fixed-term Parliaments Act: https://commonslibrary.parliament.uk/prerogative-powers-and-the-fixed-term-parliaments-act/