Can the Queen of the United Kingdom appoint her successor?
In some monarchies, a ruling monarch may choose his/her successor by public declaration, or by testament.
In other, only an elder male child may inherit the throne, with no exceptions.
There were rumors circulated in some media that the Queen of the United Kingdom may choose her grandson William as the successor. Can she legally do this?
Succession to the British throne is determined by Parliament, not by the personal decision of the monarch.
The relevant law is the Succession to the Crown Act (2013). This amends the 1701 Act of Settlement, and sets down that the oldest child of the monarch, whether male or female, will succeed to the throne upon the monarch's death.
If Prince Charles is still alive at the time the Queen dies, the law says that he will become King. Any change to the line of succession before then would require a further Act of Parliament; not just in the UK, but in 15 other countries which have the Queen as head of state. No changes were made to exclude Charles in 2013, and they are highly unlikely to be made now.
However, there are precedents for a King to abdicate, the most recent being Edward VIII in 1936. If Prince Charles so chose, he could renounce the throne immediately and make William the King in his place. This also would require an Act of Parliament; but in the case of Edward VIII the Declaration of Abdication Act was passed very rapidly, and something similar could be done again.
To this, I'd add that interfering with the line of succession is considered treason (1702 Treason Act), punishable by imprisonment for life. I wonder if it applies to the Queen interfering, though?
@yannis: There is a precedent for a King of England being executed for treason. However: (1) The Queen's personal status is such that nobody is going to prosecute her; (2) she can say whatever she wants about the succession, but by itself that will not change the effect of the law after she dies; (3) lawful attempts to alter the succession, such as the 2013 Act itself, do not count as treason.
Unless Charles unexpectedly converts to Catholicism before the queen dies, in which case he can't be king, even if he subsequently converts back.
@RupertMorrish but then also his children are excluded from the line of succession.
I'm not sure that's still true. Converting to Catholicism (for the purposes of succession) is like being dead, not like never having lived.
Would the Declaration of Abdication Act also have to be passed in all the 16 relevant countries?
@yannis The Queen has Crown immunity and cannot be guilty of a crime. (I don't know the legal theory behind the execution of Charles I; I suspect it was "might makes right".)
@StigHemmer: Yes. As the 1936 Act was in Canada and South Africa -- at the time, other Commonwealth countries like Australia had a legal route to simply adopt the British Act, which no longer exists.
@PaŭloEbermann Why? I thought being baptized catholic was considered being "naturally dead", and the claim can still fall to your children. (as long as they're not catholics)
Actually, the 2013 act also removed the ban on Catholics succeeding to the throne.
@rojomoke I'm pretty sure that goes back well before 2013. and the other comments are already discussing this
@rojomoke The 2013 act removed the restriction on people who *married* a Catholic. It still bars those people from succession who are Catholic *themselves*.
@bobsburner I was quite sure I've read that somewhere, but checking the relevant acts again I don't find anything. I might have mixed that up with the 1936 abdication, where a law was made to exclude his descendents from the succession explicitly.
@MartinBonnersupportsMonica The leading Roundheads created a crime of treason "against the realm of England".
The last English monarch to successfully control the succession was Henry VIII, and even he had to get parliament to ratify his decisions. His son, Edward VI, attempted it, leaving the crown to his cousin, Lady Jane Grey, but his half-sisters Mary and Elizabeth defeated Lady Jane's supporters.