This talk presents a case study on the voluntary agreement on emissions reduction in the Swiss transport sector. Based on expert interviews, this case deals with the motivation for signing as well as the reasons for the failure of the agreement. In contrast to purely positivist assessments, the positions of the firms signing the agreement will be considered in the qualitative part of the analysis, too. The findings based on the interviews suggest that there are potentially conflicting firm positions behind that single industry position communicated to political decision makers. Misspecification, insufficient measures as well as problems of collective action might have led to the insufficient result. Moreover, serious concerns on the effects of the voluntary agreement on market competition are discussed.