After Prime Minister William McMahon threatened him with prosecution for `` infringement of territory , '' Casley styled himself `` His Majesty Prince Leonard I of Hutt '' to take advantage of the British Treason Act 1495 in which a self-proclaimed monarch could not be guilty of any offence against the rightful ruler and that anyone who interfered with that monarch 's duties could be charged with treason .
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 .