After the government threatened him with prosecution , Casley styled himself His Royal Highness Prince Leonard I of Hutt to take advantage of a Commonwealth law that a monarch could not only not be charged , but that anyone who interfered with his duties could be charged with treason . After the government threatened him with prosecution , Casley styled himself His Majesty Prince Leonard I of Hutt to take advantage of a Commonwealth law that a monarch could not only not be charged , but that anyone who interfered with his duties could be charged with treason .