European Union – Environmental law. On a proper construction of arts 2(a), 3(1), and 3(2)(a) of Directive (EC) 2001/42, regional town planning regulations, such as those at issue in the main proceedings, laying down certain requirements for the completion of building projects, fell under the definition of 'plans and programmes' which were likely to have significant environmental effects within the meaning of that directive and should, consequently, be subjected to an environmental impact assessment. The Court of Justice of the European Union so held in proceedings concerning the validity of a decree adopted by the government of the Brussels Capital Region (Belgium) approving the regional zoned town planning regulations and the composition of the planning permission and certificate application for a certain area of Brussels.