There are a number of ways to find reports to help you with your legal research.
Government Websites
If you know who produced the report, check the Department's website. These are usually listed under the "Publications" section of the website.
TROVE
Trove is the National Library's listing of publications in Australia. This is a great place to do a topic search within the Research & Reports category. If the report was made available electronically, the record in TROVE will link to the website.
Google
The power of the indexing and searching in Google, allows you to search across multiple websites. Use the techniques in the Effective Internet Searching page of this guide to get the most effective results
Parliamentary Papers
Commonwealth - Tabled papers can be accessed via the Australian Parliamentary Website
New South Wales - the State Library of New South Wales has a comprehensive guide to reports and papers from the New South Wales Parliament.