The Opposition is the largest minority group or coalition of members in the House of Assembly who are not supporters of the Government. The party system in Australia usually makes this quite clear, as it is the second largest "political party" group in the House of Assembly. The head of this group is known as the Leader of the Opposition.
The duty of an Opposition is to oppose, but not merely in the sense of bringing the Government to a standstill. It should be the group which is best able to put the opposite point of view, to test, probe and criticise the policy of the Government. It has a duty to expose as well as oppose.
The Opposition has three major values as an "opposer of the Government". First, it is a continuous check upon any injustice that may occur and an incentive to efficiency. Secondly, criticism of the Government by the Opposition gives the voters material on which they can judge the worth of the varying policies. Thirdly, by criticising the Government, and formulating its own policies and beliefs, the Opposition is on trial as an alternative Government.
A responsible Opposition is as necessary to the effective working of Parliament as a responsible Government. It is the alternative voice loyal to the Parliamentary system of government.