The Children's Book Council of Australia (CBCA) is a volunteer run, not for profit, organisation that was established in 1945 and is comprised of branches of individual members who are passionate about children's and young adult literature. The Short List in each of the categories is decided at the Judges' Conference after extensive discussion and by secret ballot by the Judges. The Short List usually has six titles in each category.
See the Notable Books for 2017:
http://www.cbca.org.au/notables-2017