'Hansard is the name given to transcripts of parliamentary proceedings' (source). Hansard contains a record of discussions about new legislation and proposed changes to legislation.
Hansard from 1901 onwards can be searched on the ParlInfo website.
The indexes for the 2004, 2005 and 2006 printed volumes of Hansard can also be found online.
Newspaper indexes can also be used to locate significant debates
There are no separate printed indexes. Printed indexes for each sitting period (usually about half a year) are at the back of the printed volumes of Hansard. They are in two parts:
For debate on particular bills, try checking the catalogue using name of bill and the subject heading Bills. You will find results like Gene technology bill 2000: a bill for an act to regulate activities involving gene technology, and for related purposes. Not all bills will be catalogued.
You can also use the publication Federal statutes annotations to track dates legislation was passed. This will help narrow down when debates appeared in Hansard.
Newspaper indexes can also be used to locate significant debates.