Abstract The European Commission proposal on the liberalization of energy markets has been widely debated in policy, stakeholder and academic circles both for its content and the potential consequences for the structure of the EU gas and electricity markets. However, little has been said about the empirical evidence produced by the European Commission to support this legislative package. Since the Impact Assessment (IA) system has been in place, there have been concerns regarding quality and adequateness, especially when quantifying costs, benefits and risks, selecting policy options and considering stakeholder opinions. This article examines how these crucial issues were factored into the IA on the liberalization of EU energy markets. It is concluded that the selected policy option reflects the position of some stakeholders at the expense of the available evidence on its impacts on markets, society and the environment.