The European Court of Justice upheld provisions of Directive 2003/87 implemented by French legislation, which applied the greenhouse gas trading scheme to installations in the steel sector. Arcelor, a worldwide steel enterprise, challenged the directive under the principle of equality. Arcelor argued that non-ferrous metals and plastics are both industries emitting greenhouse gases, yet they are not regulated by the Directive. The Court found the differences in treatment between the steel industry and the chemical and non-ferrous metal industries to be justified based on substantial differences among the industries, such as the number of installations and the levels of direct emissions.