A tweet on my timeline caught my interest today:
Prince Harry's kids will be Americans. What if one grows up to be president and is in line for the throne at the same time? Brits are playing long-ball here, but it's a smart move. They want America back and this is how they'll do it.
Is there any legal barrier in either the UK or the USA which stipulate that the President of the United States cannot be the Monarch of the United Kingdom, or vice versa?
I can't speak to requirements for the UK monarchy, but on the US side, it appears to be legally possible for someone in line to the throne to become President. The only constitutional requirements are:
No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any Person be eligible to that Office who shall not have attained to the Age of thirty five Years, and been fourteen Years a Resident within the United States. [ref]
and
No person shall be elected to the office of the President more than twice, and no person who has held the office of President, or acted as President, for more than two years of a term to which some other person was elected President shall be elected to the office of the President more than once. [ref]
Obviously, there's no guarantee of being elected, and the nature of the situation practically writes the attack ads from opponents (similar to criticisms of Kennedy about being a Catholic and thus answerable to the Pope).
However, it's a very different story when it comes to actually inheriting the crown while in office. Article I, Section 9, clause 8 of the Constitution (also called the Emoluments Clause) states
No Title of Nobility shall be granted by the United States: And no Person holding any Office of Profit or Trust under them, shall, without the Consent of the Congress, accept of any present, Emolument, Office, or Title, of any kind whatever, from any King, Prince, or foreign State. [ref]
I think everyone can agree that becoming the King or Queen of the UK would constitute "accepting an Office or Title from a foreign State". Thus, the POTUS/heir would require Congressional approval to accept the crown. Without it, they could choose to resign as POTUS or abdicate the crown, but they could not hold both.
The same logic may apply to being named Crown Prince/ess (due to the death or abdication of a prior claimant). The person in question would still be the heir apparent, but would be unable to receive any of the associated lands or titles until Congress approved or they left office.
It's also worth noting that none of these requirements are unique to the President. Anyone holding any elected or appointed office in the US would have the same restrictions on taking the crown without Congressional approval.
I would say that in the strict reading of the law, this scenario would be possible (provided that Harry's line becomes Heir Apparent in some fashion. Presently they are not.). If challenged, Originalism interpretation of the constitution might prevent that as the line was specifically carved out in a fashion to prevent this from happening, it might prevent royalty with dual citizenship in the U.S. from becoming President. Additionally, the prospective politician will have to reside in the United States territories for 14 years.
Additionally, Prince Harry is currently fifth in line for the Throne. This would mean that Prince Charles (Father), Prince William (Brother), Prince George (Nephew), and Princess Charlotte (Niece) will all be unable to become regent. Assuming no more offspring from William, This means that any off spring from Harry would be sixth in line and has a long way to go (Or a lot of Disney villain plots to enact) before they will get that close.
Theoretically, such a situation would actually give America more power over Britain than the reverse, as POTUS is both Head of Government and Head of State where as the Monarch is only a Head of State. The Monarch of England does have the legal authority to dissolve Parliament, so that special relationship that American and England has will have a lot more special of a relationship in America's finger as now American can keep doing that until such time that the President/Monarch has a favorable PM.
But since the Prime Minister and Parliament get to set rules for being King/Queen, they can say that the Monarch must renounce dual citizenship before ascent to the throne, or bar the situation out right. After all, the last thing Britain wants is to lose power to us colonials. Brexit will be a living memory and no one is going to want to get rid out of toxic relationship with a ruling body from across the sea only to be brought into another one that quickly.
The United States constitution says in Article I, Section 9 (the Foreign Emoluments Clause):
No Title of Nobility shall be granted by the United States: And no Person holding any Office of Profit or Trust under them, shall, without the Consent of the Congress, accept of any present, Emolument, Office, or Title, of any kind whatever, from any King, Prince, or foreign State.
So someone can't be named monarch of the United Kingdom while president without the explicit consent of Congress. They would have to inherit before becoming president.
Of course, the president can't even sign a binding treaty without the concurrence of two thirds of the Senators (Article II, Section 2, the Treaty Clause) much less surrender sovereignty. To surrender sovereignty would take a constitutional amendment, which requires the acquiescence of at least three quarters of the states (Article V).
I suppose as Commander in Chief, a president could coordinate with UK invasion forces and move the US armed forces out of the way. However, the last time that the UK sent troops to the US didn't end so well. And they had official support from the sovereign then. Not to mention that the UK then had almost five times the population of what would become the US but now has about a quarter.
A better plan might be to have a lot of kids, each of whom had more kids. In several generations, they could take over the state legislatures and deliver the US to the UK. There are no legal impediments to that. Once sovereignty was surrendered, the kids could become the new nobility: Dukes and Duchesses of the states; Earls and Countesses of the counties; Marquesses and Marquessas, Viscounts and Viscountesses, Barons and Baronesses, and Baronets and Baronetesses of municipalities. That would probably be easier if they focused on royal bastards rather than legitimate children.
Twenty kids with one woman is a lot. The record is sixty-nine in twenty-seven pregnancies. Supposedly Genghis Khan fathered over a thousand children and more recently there have been examples of men with hundreds of children. So if speed is important, ditch the monogamy. The royal sperm donor should have bought the Playboy mansion instead.
Of course, they could skip the sperm donation and go straight to the bribing of potential state legislators. That could be a lot quicker.
