Constitutional law - Parliament - The Senate - Appointment of Senator - Resignation of Senator - Removal of Senator - Pre-Signed and undated letters of resignation and authorization given to leader of opposition by Sanator at time of appointment to use letters at his sole discretion to effect resignation of Senator – Senator refusing to resign - Use of the letters by the leader of oppositon to effect resignation of the Senator – Whether authority to use letters revoked - Whether letters unconstitutional - Whether the request for and use of the letters by the leader of the opposition uncon