Royal prerogative in the United Kingdom

William IV, the last monarch to arbitrarily dissolve Parliament by using the royal prerogative

One of the monarch's historic prerogatives was the dissolution of Parliament, which was "perhaps the most important residual prerogative exercised personally by the sovereign, and represents the greatest potential for controversy."[15] This prerogative was normally exercised at the request of Parliament and the prime minister, either at his or her discretion or following a motion of no confidence. Constitutional theorists have had differing views as to whether a unilateral dissolution of Parliament would be possible today; Sir Ivor Jennings wrote that a dissolution involves "the acquiescence of ministers", and as such the monarch could not dissolve Parliament without ministerial consent; "if ministers refuse to give such advice, she can do no more than dismiss them". A. V. Dicey, however, believed that in certain extreme circumstances the monarch could dissolve Parliament single-handedly, on the condition that "an occasion has arisen on which there is fair reason to suppose that the opinion of the House is not the opinion of the electors ... A dissolution is allowable, or necessary, whenever the wishes of the legislature are, or may fairly be presumed to be, different from the wishes of the nation."[16]

The monarch could force the dissolution of Parliament through a refusal of royal assent; this would very likely lead to a government resigning. By convention, the monarch always assents to bills; the last time the royal assent was not given was in 1708 during the reign of Queen Anne when, on ministerial advice, she withheld royal assent from the Scottish Militia Bill. This does not mean that the right to refuse, even contrary to the wishes of the Prime Minister, has died: the threat of the Royal Veto by George III and George IV made Catholic Emancipation impossible between 1800 and 1829, whilst George V had been privately advised (by his own lawyer, not by the Prime Minister) that he could veto the Third Irish Home Rule Bill; Jennings writes that "it was assumed by the King throughout that he had not only the legal power but the constitutional right to refuse assent".[17] The royal prerogative to dissolve Parliament was abrogated by Section 3(2) of the Fixed-term Parliaments Act 2011.[18] Section 6(1) of the Act however specifically states that the monarch's power to prorogue Parliament is not affected by the Act.[19] Nonetheless, the Supreme Court's 2019 judgment in Miller II established that the prerogative of prorogation is not absolute.

The appointment of the prime minister is also, theoretically, governed by the royal prerogative. Technically the monarch may appoint as prime minister anyone she wants to appoint, but in practice the appointee is always the person who is best placed to command a majority in the House of Commons. Usually, this is the leader of the political party that is returned to Parliament with a majority of seats after a general election. Difficulties may result with a so-called hung parliament, in which no party commands majority support, as last occurred in 2017. In this situation, constitutional convention is that the previous incumbent has the first right to form a coalition government and seek appointment.[20] If the prime minister decides to retire in the middle of a parliamentary session, then unless there is a clear "prime minister-in-waiting" (eg. Neville Chamberlain in 1937 or Anthony Eden in 1955) the monarch in principle has to choose a successor (after taking appropriate advice, not necessarily from the outgoing prime minister), but the last monarch to be actively involved in such a process was George V, who appointed Stanley Baldwin rather than Lord Curzon in 1923. In more modern times, the monarch left it to the politicians involved to choose a successor through private consultations (Winston Churchill in May 1940, Harold Macmillan in January 1957, Alec Douglas-Home in October 1963). Nowadays, the monarch has no discretion, as the governing party will elect a new leader who will near-automatically be appointed as he or she commands the support of the majority of the Commons (most recently Theresa May in 2016 or Boris Johnson in 2019).[21]

The most noted prerogative power that affects the judicial system is the prerogative of mercy, which has two elements: the granting of pardons and the granting of nolle prosequi. Pardons may eliminate the "pains, penalties and punishments" from a criminal conviction, though they do not remove convictions themselves. This power is commonly exercised on the advice of the Secretary of State for the Home Department; the monarch has no direct involvement in its use. Exercises of this power may also take the form of commutations, a limited form of pardon where the sentence is reduced, on certain conditions. The granting of a pardon is not subject to judicial review, as confirmed by Council of Civil Service Unions v Minister for the Civil Service,[22] but the courts have chosen to criticise its application or lack thereof, as in R v Secretary of State for the Home Department, ex parte Bentley.[23][24] Granting nolle prosequi is done by the Attorney General of England and Wales (or the equivalent in Scotland or Northern Ireland) in the name of the crown, to stop legal proceedings against an individual. This is not reviewable by the courts, as confirmed by R v Comptroller of Patents, and does not count as an acquittal; the defendant may be brought before the courts on the same charge at a later date.[25]

The royal prerogative is in much use in the realm of foreign affairs. It is the monarch who recognises foreign states (although several statutes regulate the immunities enjoyed by their heads and diplomatic representatives), issues declarations of war and peace, and forms international treaties. The monarch also has the power to annex territory, as was done in 1955 with the island of Rockall. Once territory has been annexed, the monarch has complete discretion as to the extent to which the government will take over the former government's liabilities; this was confirmed in West Rand Central Gold Mining Company v The King.[26][27] Monarchs also have the power to alter British territorial waters and cede territory. Their freedom to do these things in practice is doubtful, in that they might deprive British citizens of their nationality and rights. When the island of Heligoland was ceded to Germany in 1890, Parliamentary approval was first sought.[28] Monarchs can also regulate colonies and dependent territories by exercising the prerogative through Orders in Council. The courts have long fought against the monarch's use of this power: in R (Bancoult) v Secretary of State for Foreign and Commonwealth Affairs (No 2),[29] the Court of Appeal ruled that using Orders-in-Council to frustrate judicial rulings was an unlawful abuse of power, although this ruling was later overturned.[30]

A judgment delivered in the Court of Appeal in 1988 (ex parte Everett), and re-stated in a ruling of the High Court delivered in July 2016,[31] confirmed that granting or withdrawing British passports has always been an exercise of the royal prerogative, and continues to be exercisable at the Secretary of State's discretion.

Under the common law, citizens have the right freely to leave and enter the United Kingdom. In R v Foreign Secretary, ex parte Everett,[32] the courts held that it was their right to review the granting of passports to, and the withholding of passports from, British citizens. The writ of ne exeat regno is also used to prevent a person leaving the country. The right to make treaties is a disputed prerogative power: under Blackstone's definition, a prerogative power must be one unique to the monarch.[33]

Monarchs also have power to exercise their prerogative over the granting of honours, the regulation of the armed forces and ecclesiastical appointments.[34] Although the granting of most honours is normally decided by the executive, the monarch is still the person who technically awards them. Exceptions to this rule are membership of the Order of the Garter, the Order of the Thistle, the Order of Merit, the Royal Victorian Order and the Royal Victorian Chain, which the monarch has complete discretion to grant.[35] In relation to the armed forces, the monarch is the Commander in Chief, and members are regulated under the royal prerogative. Most statutes do not apply to the armed forces, although some areas, such as military discipline, are governed by Acts of Parliament. Under the Crown Proceedings Act 1947, the monarch is the sole authority for the armed forces, and as such their organisation, disposition and control cannot be questioned by the courts.[36] This exercise of prerogative power gives the Crown authority to recruit members of the armed forces, appoint commissioned officers, and establish agreements with foreign governments to station troops in their territory.[37] The prerogative empowers the monarch to appoint bishops and archbishops in the Church of England,[38] and to regulate the printing and licensing of the authorised Church of England version of the Bible.[39] The monarch also exerts a certain influence power on his or her weekly and closed conversations with the Prime Minister of the United Kingdom.

R v Secretary of State for the Home Department, ex parte Northumbria Police Authority, recognised that the prerogative also includes the power to "take all reasonable steps to preserve the Queen's peace", and in Burmah Oil Co. v Lord Advocate, the House of Lords took the view that it extended to "doing all those things in an emergency which are necessary for the conduct of [the Second World War]."[40]

Several influential decisions of the House of Lords have determined the limited scope for the use of prerogative powers. In 1915, an appeal was made to the House of Lords, Re Petition of Right ("Shoreham Aerodrome Case"), but during the appeal the case was settled and the appeal withdrawn when the Crown agreed to pay compensation.[46] The appeal was from a unanimous decision of the Court of Appeal that the Crown, both under the statutory Defence of the Realm Regulations and by the royal prerogative, was entitled to take and occupy, for military purposes in wartime, a commercial airfield on the south coast. The government argued that this action was to defend against an invasion; the courts held that for the prerogative to be exercised, the government must demonstrate that a threat of invasion exists. This was backed up by The Zamora (1916),[47] where the Privy Council, on appeal from the Prize Court, held generally that to exercise a power not granted by statute (such as a prerogative power) the government must prove to the court that the exercise is justified.[48] The next decision came in Attorney General v De Keyser's Royal Hotel Ltd (1920),[49] where the House of Lords confirmed that a statutory provision in an area where prerogative powers are in use "abridges the Royal Prerogative while it is in force to this extent – that the Crown can only do the particular thing under and in accordance with the statutory provisions, and that its prerogative power to do that thing is in abeyance".[50]

This principle of statutory superiority was extended in Laker Airway Ltd v Department of Trade, concerning the revocation of a commercial airline operator's licence (December 1976),[51] where it was confirmed that prerogative powers could not be used to contradict a statutory provision, and that in situations to which the power and the statute both applied, the power could only be used to further the aim of the statute.[52] Another extension came with R v Secretary of State for the Home Department, ex parte Fire Brigades Union,[53] where the Court of Appeal held that even if a statute had not yet come into force, the prerogative could not be used to "conflict with Parliament's wishes" (in that case using its discretion to choose a start date to delay, perhaps indefinitely, the introduction of a statutory compensation scheme).[54]

Whilst the royal prerogative is deployed by the UK government when making (and unmaking) treaties, the Supreme Court held in R (Miller) v Secretary of State for Exiting the European Union that the government could not use the prerogative to serve notice of termination of the UK's membership of the EU (under Article 50 of the Treaty on European Union). Instead legislative authority via an Act of Parliament was required by the Government. The Court's reasoning in the initial hearing was that such a notice would inevitably affect rights under domestic law (many EU rights having direct effect in the UK). On the assumption – later proven false[note 1] – that triggering Article 50 would inevitably result in Brexit, using the prerogative in this way would therefore frustrate the intention of Parliament to confer those rights. This reasoning was maintained in the subsequent Supreme Court hearing, although that judgement devoted more attention to the fact that Parliament had voted the UK into what was then the EEC by statute in 1972, which under the principle of De Keyser's Hotel (1920) superseded the normal prerogative power to enter into treaties. Following this decision, Parliament decided to provide legal authorisation to the Government to serve a notice in accordance with Article 50. This was duly granted in the European Union (Notification of Withdrawal) Act 2017 and Theresa May exercised the power on 29 March 2017.

Before the modern judicial review procedure superseded the petition of right as the remedy for challenging the validity of a prerogative power, the courts were traditionally only willing to state whether or not powers existed, not whether they had been used appropriately.[54] They therefore applied only the first of the Wednesbury tests: whether the use was illegal. Constitutional scholars such as William Blackstone consider this appropriate:

In the exertion therefore of those prerogatives, which the law has given him, the King is irresistible and absolute, according to the forms of the constitution. And yet if the consequence of that exertion be manifestly to the grievance or dishonour of the kingdom, the Parliament will call his advisers to a just and severe account.[57]

During the 1960s and 70s this attitude was changing, with Lord Denning saying in the Laker Airway case that "seeing that the prerogative is a discretionary power to be exercised for the public good, it follows that its exercise can be examined by the courts just as any other discretionary power which is vested in the executive." The most authoritative case on the matter is Council of Civil Service Unions v Minister for the Civil Service, generally known as the GCHQ case. The House of Lords confirmed that the application of judicial review would be dependent on the nature of the government's powers, not their source. Foreign policy and national security powers are considered outside the scope of judicial review, while the prerogative of mercy is considered within it, as per R v Secretary of State for the Home Department, ex parte Bentley.[58]