From the Senate Website:
The role of committees is to investigate and to draw attention to what they find. They throw ‘light in dark corners’ and give advice.
Like many deliberative assemblies, the Senate finds it useful to delegate responsibility for certain tasks to small groups. The Senate may refer a particular matter to a committee because the matter warrants detailed examination, because the Senate wants information to be collected, or because it wants to hear views on the matter. These tasks are more easily undertaken by a small group of senators rather than by the Senate as a whole. Committees encourage and enable senators to develop special interests and expertise in particular aspects of public policy. They also provide an opportunity for organisations and individuals to make representations to Parliament and to have their views placed on the public record.
Participation in committees has become a very important aspect of the work of senators. More time is spent by senators attending committee meetings and hearings than in attending sittings of the Senate.