(in Britain) an Act of Parliament in 1701, saying that the children of James I's granddaughter Sophia would be the future kings and queens. The government made this law because the king at that time, William III, had no children, and they wanted to stop the CatholicStuarts from becoming kings and queens. Sophia was a Protestant. She was married to the Elector (= a type of prince) of Hanover. Their son became King George I, the first king of the House of Hanover.