Abstract
Strategic environmental assessment (SEA) is intended to go beyond the assessment of the likely environmental consequences of specific projects. However, SEA relies formally on a conceptual and methodological background that is centred on the analysis of likely environmental impacts of decisions related to policies, plans and programmes. This paper attempts to find a common theoretical denominator for the different demands placed on SEA when it is imposed on a case study. The concept of decisional environment values (DEVs) is the suggested approach: DEV is defined here as an objective entity that could constitute the study object of environmental assessment.