What is the royal prerogative?

Prerogative powers are powers which have belonged to the monarch since the Middle Ages, but in modern times are exercised largely by government ministers. The most important powers exercised by ministers are the power to make war and deploy the armed forces; to conduct foreign policy and make treaties; to make public and judicial appointments; to issue passports; and to grant pardons and honours.

Reserve powers

But the King still exercises some prerogative powers himself, known as his reserve powers or the personal prerogatives. The most important of these are the power to appoint and dismiss ministers, including the Prime Minister; to summon and prorogue parliament, i.e. end the current parliamentary session; and to give royal assent to bills passed by parliament. Royal assent to bills is automatically granted, once a bill has been passed by both houses of parliament. The other powers are exercised on the advice of ministers, advice which – by convention – the King is normally expected to follow. But as guardian of the constitution, the King has power to dismiss a Prime Minister who refuses to resign after losing the confidence of the House of Commons; and in future. The Supreme Court’s Miller/Cherry ruling also provides space for a monarch to refuse a future request for prorogation if its effect would be to frustrate or prevent parliament from carrying out its constitutional functions.

Accountability through the courts

Ministers are accountable for their use of prerogative powers – the same is true for statutory powers (powers conferred on ministers through Acts of Parliament). If there is concern that ministers have used prerogative powers improperly, the exercise of these powers can be regulated by the courts. A recent example of this is the aforementioned 2019 Miller/Cherry ruling, in which the Supreme Court decided that Boris Johnson’s advice to the then-Queen to prorogue parliament for five weeks was unlawful.

Replacement and regulation by Acts of Parliament

The past two decades have seen certain prerogative powers become subject to greater control by parliament. Some prerogative powers been replaced by statutory powers. The power to appoint and regulate civil servants was placed on a statutory footing by the Constitutional Reform and Governance Act 2010 (CRAG 2010). The Fixed-term Parliaments Act 2011 removed the monarch’s prerogative power to dissolve parliament and placed dissolution in the hands of parliament, though this was subsequently reversed by the Dissolution and Calling of Parliament Act 2022. In other cases, the power remains a prerogative one, but statute gives parliament control over its use: CRAG 2010 codified the convention that new treaties have to be laid before parliament before the government can ratify them. 

Regulation by constitutional convention

Some prerogative powers, like the war-making power, may be regulated by constitutional convention. Following the decision to intervene in Iraq in 2003 – which was approved by a vote in the Commons – a convention seemed to emerge that, before troops are deployed overseas, the Commons should normally be allowed to vote on the matter; but that was not followed when Theresa May authorised airstrikes in Syria in April 2018.

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