Currently, there is a Danish State Visit to Vietnam going on. This involves both the Queen and the Crown Prince – which means that according to Danish law, someone has to be home in Denmark to mind the store, so to speak. This time around, Prince Joachim was the fortunate one.
The purpose of this is that there should always be someone in Denmark who can “lead the government.” These days the government can probably lead itself, but these are the kind of formalities that monarchies run on. Come to think of it, this is the kind of formality that governments in general run on.
I’ve seen the role that Prince Joachim or Princess Benedikte fills when this sort of thing is happening being described as being a regent, which might be a correct translation, but is slightly inaccurate.
The Danish terminology, much like the differences in titles to who is in line to the throne and who is not, have certain nuances that may not be quite as literally translated to the English language, as other terms.
The most accurate term I’ve been able to come up with for what Prince Joachim and Princess Benedikte are, is Chancellor of the Realm. (Rigsforstander.)
The times when Crown Prince Frederik is standing in for his mother, he is the regent, as per the Danish law on the subject.
When Prince Joachim or Princess Benedikte do it – they are acting as Chancellor of the Realm, not as regents.
According to the law, the first in line after the monarch is named the regent when the monarch cannot be in the realm, or is ill. However, if he or she has similar issues, the monarch may appoint a Chancellor of the Realm to take their place.
While the regent has to be the first person in direct line to the throne, the Chancellor of the Realm either has to be of age, and in line to the throne; or of age, a Danish citizen and belong to the Danish evangelical-Lutheran church. The law from 1871 declares that it has to be a prince or a male, but as one can see from Princess Benedikte’s appointment, as well from Queen Ingrid, that bit has been ignored.
The latter gave her oath to the constitution in 1972, after her husband’s death, while Crown Prince Frederik was under-age, so as to share in the family responsibilities. Crown Princess Mary and Princess Marie could therefore theoretically fulfill the role as well, but neither they, the Prince Consort or the former Princess Alexandra have ever sworn an oath to the constitution to take on that set of obligations.
At the moment it is therefore just Prince Joachim and Princess Benedikte who can act as Chancellors of the Realm. The other adult person in line to the Danish throne, Princess Elisabeth, as far as I have been able to discover, has not given her oath to the constitution, and has not been named Chancellor of the Realm.
The purpose of the particular law dictating all of the above, is first and foremost to have a system of who governs Denmark, in place if the Monarch is underage, ill or is absent from his or her duties.