Companies from the steel industry claimed that decree n°2004-832, which transposes the EU directive of October 13, 2003 establishing a system of exchange of greenhouse gas emission quotas in the European Union, was illegal. The Companies claimed that the directive violated the principle of equality since it provided for a difference of treatment between certain industries. Indeed it included the companies from the steel industry but excluded companies from the plastic and aluminum industries. The French Conseil d'Etat referred the question to the European Court of Justice for a preliminary ruling. The European Court of Justice held that the directive did not violate the principle of equality as the difference of treatment between the industries was justified by objective criteria, such as the very low carbon dioxide emissions from the non-steel industries.