On 29 July 2019, the Grand Chamber of the CJEU ruled on the interpretation of Directive 2011/92 on the assessment of the effects of certain public and private projects on the environment and Directive 92/43 on the conservation of natural habitats and of wild fauna and flora with respect to the obligation to subject Belgian legislative measures providing for the restarting of the operation of a nuclear power plant and the deferral of the deactivation of another nuclear power plant to an assessment of their environmental effects (EIA). The Court held that the measures at issue constitute a “project' within the meaning of both directives, since they necessarily involve major works altering the original plants. Accordingly, such projects must be subject to an EIA prior to the adoption of the measures authorising them. A Member State may, under Directive 2011/92, exempt a project from the requirement to conduct an EIA in order to ensure the security of its electricity supply only where it can demonstrate that the risk to the security of that supply is reasonably probable and that the project in question is sufficiently urgent to justify not carrying out the assessment. However, the possibility of granting such an exemption is without prejudice to the obligation to conduct an EIA regarding projects that have transboundary effects. Furthermore, while the objective of ensuring the security of a Member State's electricity supply at all times constitutes an imperative reason of overriding public interest within the meaning of Directive 92/43, which justifies proceeding with the project in spite of a negative assessment and in the absence of alternative solutions, that is not so where the protected site likely to be affected by the project hosts a priority natural habitat type or a priority species. In such a case, only the need to aver a genuine and serious risk of rupture of the electricity supply in the Member State concerned would constitute a public security ground, within the meaning of that directive, and may ...