General Principles
Effectiveness
Under the principle of cooperation in good faith laid down in Article 4(3) of the Treaty on European Union (TEU), Member States are required to give full effect to the provisions of the EU law. This means they have to interpret the national law in line with EU law, to refuse to apply any conflicting provision of national law (see above) and also to nullify the unlawful consequences of a breach of EU law. Such an obligation is owed, within the sphere of its competence, by every organ of the Member State concerned (Case C-72/95 Kraaijeveld and Others, para. 61; Case C-435/97 WWF and Others, para. 71).
In Case C-201/02 Wells, the CJEU held it is for the competent authorities of a Member State to take, within the sphere of their competence, all the general or particular measures necessary to ensure that projects are examined in order to determine whether they are likely to have significant effects on the environment and, if so, to ensure that they are subject to an impact assessment. Such particular measures include, subject to the limits laid down by the principle of procedural autonomy of the Member States, the revocation or suspension of a consent already granted, in order to carry out an assessment of the environmental effects of the project.
The principle of effectiveness also means that the detailed procedural rules governing actions for safeguarding rights which individuals derive from EU law must not make it in practice impossible or excessively difficult to exercise these rights (Case C-71/14 East Sussex County Council, para. 54-55; Case C-416/10 Kri˛an, para. 106).
In Case C-115/09 Bund für Umwelt und Naturschutz Deutschland, Landesverband Nordrhein-Westfalen, the CJEU held that the environmental NGOs must be able to rely on the same rights as individuals and that it would be contrary to the objective of giving the public concerned wide access to justice and at odds with the principle of effectiveness if such organisations were not also allowed to rely on the impairment of rules of EU environment law solely on the ground that those rules protect the public interest (see also Case C-570/13 Gruber, regarding the rights of individuals).
The Member States' obligation to achieve the result envisaged by EU law also means that they have to ensure that infringements of EU law are penalised under conditions, both procedural and substantive, which are analogous to those applicable to violations of national law of a similar nature and importance and which, in any event, make the penalty effective, proportionate and dissuasive (see opinion of GA in Case C-304/02 Commission v France).