The "Constitution Act, 1867", outlines that persons are to be summoned and appointed for life to the 's Privy Council by the governor general, though convention dictates that this be done on the advice of the sitting prime minister. As its function is to provide the vehicle for advising the Crown, the members of the Privy Council are predominantly all living current and former ministers of the Crown. In addition, the chief justices of Canada and former governors general are appointed. From time to time, the leader of Majesty's Loyal Opposition and heads of other opposition parties will be appointed to the Privy Council, either as an honour or to facilitate the distribution of sensitive information under the "Security of Information Act", and, similarly, it is required by law that those on the Security Intelligence Review Committee be made privy councillors, if they are not already. To date, only Prime Minister Paul Martin advised that parliamentary secretaries be admitted to the Privy Council.