Constitution – Chapter 4 – Part 1 -Appointment of Senators
Appointment of Senators.
30.- (1) Of the Senators-
a) one-third or their number (excluding any Senator who holds the office of Attorney-General) shall be appointed by the Governor-General, acting in accordance with the advice of the Leader to the Opposition; and
b) the others shall be appointed by the Governor-General, acting in accordance with the advice of the Prime Minister.
(2) In this section “one-third” means, in relation to a number of Senators that is not a multiple of three, one-third of the next higher number that is such a multiple.