The wedding of Prince Charles and Camilla Parker Bowles is on course after a decision by Registrar General Len Cook.
Public opinion over the wedding is split
Mr Cook rejected 11 legal objections to the wedding at the Guildhall in Windsor on 8 April.
Objections or "caveats" can be lodged against any civil wedding in England and Wales, but are not a common occurrence.
The General Register Office does not have exact figures for the number of caveats but estimates there are only "a handful" of objections to civil ceremonies each year.
Nor does the Church of England keep exact figures, but says objections in ceremonies are "extremely rare".
Typically, what few caveats there are to civil weddings usually come from an objector claiming someone is not yet properly divorced from a previous spouse.
There is obviously no question of this in Prince Charles' wedding - instead the 11 objectors are all likely to have claimed that the wedding was illegal.
The only objector who has so far spoken to the press - Rev Paul Williamson - said the wedding was incompatible with the 1949 Marriage Act.
The business of caveats is not a matter of public record, and a search of British newspaper archives over the last two decades only shows one example of a register office wedding being stopped.
For civil ceremonies, every couple has to give 15 days' notice to obtain the certificate that allows them to marry.
They must present, in person, to the superintendent registrar at their local office any evidence showing they are free to marry, such as decree absolutes demonstrating that any divorce has been finalised.
Len Cook is better known as national statistician
During this 15-day notice period any person can register a "caveat" using forms obtained from the register office, giving a legal reason why the wedding cannot proceed.
In the prince and Mrs Parker Bowles' case, the superintendent registrars - in charge of the local register offices at Chippenham and Cirencester - passed the decision on to the Registrar General, Mr Cook.
Mr Cook's decision can be challenged by the objectors who have lodged the caveats. In the event it had gone the other way, the couple could also have started proceedings.
Parties can petition for judicial review, which if accepted by a judge, means there could potentially be a delay to the wedding while the matter is decided in court.
Some experts have pointed to the 1836 Marriage Act, which created register office weddings in England and Wales and is clear that members of the Royal Family are not eligible.
They say the 1949 Marriage Act does nothing to affect this, and indeed this was the basis for the advice given to Princess Margaret when she announced her plan to marry Group Captain Peter Townsend in the 1950s.
But Lord Falconer, the lord chancellor, has spoken on behalf of the government, saying it has a different view of the 1949 act and noting that the Human Rights Act demands all legislation be interpreted in a way that respects individuals' right to marry.
Mr Williamson, from St George's Church, Feltham, in London, has been unequivocal in his opposition and has vowed to protest at the ceremony if necessary.
He was quoted in newspapers saying: "I do not believe there is any provision in law for Charles to marry anywhere else other than in church and, as a divorcee, he cannot do that."