This thesis examines the role of corporate power in the decision making and regulatory processes for major hazard sites in the UK. In particular, emphasis is placed on the role of risk analytical techniques and the associated use of technical expertise in the public inquiry process by focusing on two areas, Canvey Island (Essex) and Ellesmere Port (Cheshire), over a twenty year period. Evidence shows that the ability of public groups to intervene effectively in the decision making process varies both .spatially and temporally. In order to set this data within a theoretical framework the analysis of public inquiries in these areas takes place in the context of three competing perspectives on power, namely pluralist, elitist and Marxist. Through the use of a number of mediating concepts the three theoretical persectives on power are married to the empirical data derived for the two areas. The research shows that each of the perspectives fails to provide an adequate explanation for events. Against this background some of the models of scientific expertise within decision making are evaluated and it is suggested that such models need to be set in a wider economic and social framework than had previously been allowed for by some authors. It is argued that risk analysis can be used to support the interests of powerful groups and as a consequence its validity as an input into decision making needs to be subjected to more critical scrutiny than has previously been the case. The thesis concludes by making a number of recommendations for the various bodies involved in making judgements about major hazards.