The purpose of this case study was to evaluate the changes in opinion of a group of future teachers on the danger of mobile telephones. The opinions were determined before and after epistemological work and role-playing in a form of a legal suit. This activity was part of pre-service teachers’ initial training in a one-week module dedicated to prepare them to lead debates on controversial scientific issues. The fifteen participants were future physical science and biology teachers. A comparison of pre- and post-test evaluations revealed that these pre-service teachers were less sure of the risk involved in using mobile telephones following the activity and that the role-playing affected their epistemological interpretation of the research results.