A more thorough explanation:

The Statute of Allegiance de Facto was a law that required subjects to pledge their loyalty to the current (de facto) king or ruler, and protected them from any consequences for doing so. This law was enacted during the reign of King Henry VII in England, in the year 1495.

For example, if a new king had taken the throne by force or through other means that were not entirely legitimate, the Statute of Allegiance de Facto would require all subjects to swear allegiance to that king, even if they did not necessarily agree with his claim to the throne. By doing so, they would be protected from any punishment or retribution for their loyalty.

This law was important in maintaining stability and order during times of political upheaval or uncertainty, as it ensured that the people would remain loyal to the current ruler, regardless of how they came to power. It also helped to prevent civil unrest or rebellion, as those who swore allegiance to the de facto king were legally protected from any consequences for doing so.