Can a reigning UK monarch change the line of succession by royal prerogative or legislation?
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Executive summary
A UK sovereign cannot unilaterally rewrite the order of succession by exercise of personal prerogative; succession is governed by statute and international agreement between the Commonwealth realms and has been altered only by Acts of Parliament such as the Succession to the Crown Act 2013, which took effect in the realms in March 2015 [1] [2]. Removing someone from the line of succession requires primary legislation and—by convention—consent from the other Commonwealth realms that share the Crown [3] [4].
1. The law, not the will of the monarch
The core point is constitutional: British succession rules are statutory. The Bill of Rights 1689, the Act of Settlement 1701 and later Acts determine who can inherit; Parliament, not the monarch alone, has the legal power to change those rules [4] [5]. Modern changes—ending male primogeniture and removing the disqualification for marrying a Roman Catholic—were effected through legislation agreed by the realms and enacted as the Succession to the Crown Act and related measures [2] [1].
2. Precedent: collective, legislative change in 2011–2015
The recent, high-profile reform of succession rules began with an agreement by the prime ministers of the Commonwealth realms in 2011 and was implemented by legislation in the UK and other realms; the changes only came into force after the necessary statutes were enacted, with effect across the realms in March 2015 [2] [1] [4]. That episode illustrates the two limits on unilateral action: domestic parliamentary law and the international convention among realms that share the Crown [2] [4].
3. Removing an individual: statute required, and realm consent by convention
If the Crown or government wanted to remove an individual from the line, the practical instrument is an Act of Parliament. Parliamentary measures have been used historically to alter succession and titles, and contemporary commentary and parliamentary briefing note that removal from the line would require legislation—and, by the convention set out in the preamble to the Statute of Westminster 1931, the consent of every other Commonwealth realm [3] [4]. The House of Commons Library explicitly states: a member of the royal family can be removed from the line by legislation, but conventionally this would need the realms’ consent [3].
4. Royal prerogative: powers over honours, not succession
The monarch retains many personal prerogatives—granting honours, military appointments and patronages—but those prerogatives do not extend to rewriting the statutory rules of succession. The removal of styles and honours (for example, decisions about HRH usage or military roles) can be exercised by the sovereign or on ministerial advice, and such steps do not by themselves change the legal line of succession [3]. Recent examples show titles and patronages being changed without altering succession positions [3] [6].
5. The Commonwealth dimension: multiple sovereign states share one order
The United Kingdom is one of the Commonwealth realms that share the monarch as head of state; when the realms agreed to change succession rules in 2011 they did so collectively because the same person is monarch of multiple independent states. That shared character means practical changes to who may be monarch require coordinated action across those governments [4] [2]. The 2011 Perth agreement and follow-up legislation underline that reality [2] [1].
6. Historic examples and limits on royal discretion
Historically, monarchs and Parliament have clashed over succession, and Parliament ultimately established the legal framework in the 17th–18th centuries; the Treasons Act 1571 and later statutes affirmed Parliament’s authority in succession disputes [4]. While wills and royal instruments once influenced succession in particular cases, the prevailing constitutional settlement puts statutory rule-making in Parliament’s hands [4].
7. Practical politics: government and public opinion matter
Even where legal routes exist (e.g., Parliament passing a law), political realities matter: governments cautioned publicly that they had “no plans” to alter certain people’s place in the order, and parliamentary processes and public debate would shape any attempt [6] [7]. The 2011–2015 reforms themselves required political negotiation among multiple governments before legislation followed [2] [1].
Limitations and missing items
Available sources do not mention any recent case where a reigning UK monarch alone attempted to alter the statutory succession order without parliamentary action. They also do not provide a step‑by‑step legal mechanism for how each Commonwealth realm would give consent under the Statute of Westminster convention (not found in current reporting) [3] [4].
Bottom line: statutory rule and collective agreement govern who succeeds. The monarch can remove honours and styles by prerogative but cannot, on personal authority alone, change the legally established line of succession; any such change requires Parliament and, by longstanding convention, the assent of the other realms that share the Crown [4] [3] [1].