Pressure groups are those within the environment that can influence the organisation's policies and practices, formally through the legislative system, or informally by bringing pressure to bear through the activities of special interest groups. For example, in Australia, the power of the unions to influence organisation's work and labour practices fluctuates in response to a number of factors. These are largely influenced by the persuasion of the governments in power, and the economic climate. Other pressure groups such as Greenpeace, or the Australian Conservation Foundation cannot exercise any legally based influence on organisations, but nevertheless, they have a considerable impact. Their power lies in their ability to tug on the collective conscience, using the media to communicate and influence the general public.