Siting controversies are commonplace, as well against the construction of roads, railways, nuclear waste disposals, as against windfarms. Local citizens resist against siting decisions taken by the authorities, following a dynamics often quoted as ‘Not In My Back Yard’. Yet contested for its lack of analytical value, NIMBY is still used strategically by actors to qualify citizens as irrational and egoistic. Beyond this labeling, many factors are investigated to understand the dynamics behind siting controversies. In this paper, we focus on the impact of the legal procedure structuring the implantation of windfarms in the Walloon Region (Belgium), and its translations within different decision-making processes in specific case studies. To that regard, we consider the legal procedure as a ‘public policy instrument’. It is neither neutral nor natural, and carry values and interests. It organizes interpersonal relations between actors, and is potentially catalyzer of frustrations. In addition, this legal procedure is the object of translations within different contexts, including different actors participating to specific decision-making processes. The empirical approach of this paper is based on case studies data and on the use of an innovative methodology called ‘Open Process Workshop’. This methodology consists of a structured workshop with key stakeholders, during which the legal procedure is questioned. Overall, we demonstrate that the focus on the legal procedure – and its translations within different decision-making processes – allows systemic analysis providing deep understandings of controversies and reaffirming the interlinks between ‘the social’ and ‘the technical’ in such controversies. In addition, we argue that the methodology used fosters the production of innovative knowledge, mutual understanding, and collective learning between the participants.