In United Kingdom constitutional law, prorogation is an act usually used to mark the end of a parliamentary session. Part of the royal prerogative, it is the name given to the period between the end of a session of the UK Parliament and the State Opening of Parliament that begins the next session. The average length of prorogation since 2000 (i.e. calendar days between the date of a new session and prorogation of the previous Session) is approximately 18 days. The parliamentary session may also be prorogued before Parliament is dissolved. The power to prorogue Parliament belongs to the monarch, on the advice of the Privy Council. Like all prerogative powers, it is not left to the personal discretion of the monarch but is to be exercised, on the advice of the prime minister, according to la