A 300-year rule is begging the question as to whether Queen Elizabeth technically has legal custody of her minor great-grandchildren
Prince Louis christening
Credit: PA Images/Sipa

A 300-year rule is begging the question as to whether Queen Elizabeth technically has legal custody of her minor great-grandchildren.

In 1717, a major disagreement that King George I had with his son over how he was raising his children led to him being granted authority over his grandchildren. Judges ruled in the king’s favor, stating that the “king’s right of supervision extended to his grandchildren and this right of right belongs to His Majesty, King of the Realm, even during their father’s lifetime.”

But the centuries-old decree does not pertain to Queen Elizabeth’s authority over her own great-grandchildren, including Prince George, Princess Charlotte and Prince Louis.

“This isn’t an Act of Parliament, but a royal prerogative established in the early 18th century, so it is not legally binding,” Joe Little, managing editor of Majesty, tells PEOPLE.

“It is nothing more than a royal prerogative and is archaic and would have little bearing today,” he continues. “The circumstances would have to be pretty extreme for the Queen to invoke it on behalf of her great-grandchildren. Given that there are parents, and grandparents alive – not to mention all the aunts and uncles – there is a huge support structure already in place for the great-grandchildren.”

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The original delegation was put into effect in 1717 and again in 1772, the same year the Royal Marriages Act went into effect (the law which required Prince Harry to seek Queen Elizabeth’s approval to marry Meghan Markle).

The Royal Marriages Act 1772 gave the monarch the right to veto the marriage of a member of his or her family. That law has since been repealed and was replaced by more relaxed restrictions.

Now, the law only applies to the first six in line to the throne, which as of now are Prince Charles, Prince William, Prince George, Princess Charlotte, Prince Harry and Prince Andrew. Princess Beatrice and Princess Eugenie used to be included in that list, but were moved down the line of succession after George and Charlotte’s births.

Although Queen Elizabeth doesn’t have any legal authority over her minor great-grandchildren, she does have input on any major parenting decisions. For example, the Queen must approve any and all air travel as two heirs aren’t allowed to travel together in order to protect the lineage.

While the Queen has occasionally bent the rules when it comes to air travel and allowed two heirs to fly together, Charles and William rarely ride in the same car together. However, Prince William and Prince George often do, perhaps because George is (a little) further down the line of succession. The rule does not apply to Prince Harry, as he is now sixth in line.