This article analyses legal aspects of the Swedish wind power development, theoreticallybased on how different types of knowledge are represented in legal contexts, mainly inthe courts. A sample of appealed wind power permits is analysed, a handful of relevantinformants are interviewedincluding two judges in the Land and Environment Courtand the appeal courtand the legal setting is analysed. Of key interest here is theinterplay between expert and lay statements in the court cases, which here is related tothe concepts of calculating and communicative rationalities that are developed in theplanning literature. The results indicate that the juridificationwhich takes place as apermit issue is appealed in the judiciary systemsupports the calculating rationalitymore than the communicative, and that the plaintiffs often attempt to adapt in how theyshape their argumentation.