The relationship between expertise and politics has traditionally been described in terms of science speaking truth to power. Science strengthens governmental effectiveness and depersonalises power, linking legitimacy to the credibility of observation. The environment is a case in point: what we know about it is largely associated with science. Today, however, expertise is both increasingly sought and thrown onto the terrain of conflict. The politicisation of expertise breaks with the alleged alternative between democratic and technocratic policymaking. The concept of expertise and its politicisation in the context of contentious politics is elaborated. Three case studies show that expertise affects the discursive opportunity structure of controversies, that the ‘politics of facts’ intermingles in subtle ways with the politics of interests and values, and that there is no linear sequence between politicisation and depoliticisation.
