Abstract
Public decisions concerning large projects with detrimental environmental or heritage impacts involve value conflicts which stem from the diverse interests and variety of ways of evaluating the costs and benefits of such projects. They are also framed by institutionalised procedures and practices which favour certain concerns to the detriment of others. This paper aims to contribute towards a better understanding of how these procedures and practices, namely decision support tools such as the Environmental Impact Assessment (EIA), tend to shape public decision-making processes in particular ways. It draws on a study of the public controversy surrounding the Foz Tua dam in Portugal, with a focus on the values upheld by the different parties in the controversy and their interplay in the production of justifications, specifically the actors’ positions on values and value conflicts and the restrictions posed by institutionalised public decision-making procedures on the expression and consideration of certain values.