Regulatory Impact Assessments (RIAs) in European contract law, i.e. reports preceding planned legislative measures, should increase evidence-based decision making. Unfortunately, RIAs in this area show serious, persistent shortcomings. Particularly, assumptions in RIAs lack support, policy options are not neutrally assessed and there is insufficient coordination between planned and existing European measures. Do these shortcomings constitute violations to the principles of subsidiarity and proportionality? Are the problems in RIAs also problems according to the Commission guidelines for impact assessments and have they been signalled by the Impact Assessment Board? If not, what is the added value of these soft instruments and how can RIAs best be improved?