A fundamental judgment of the Court in respect of principles, the Costa v ENEL judgment shows that the EEC Treaty has created its own legal system which has become an integral part of the legal systems of the Member States, and that Community law takes precedence over national law.

In this judgment, the Court supplements the Stauder precedent by stating that respect for fundamental rights forms an integral part of the general principles of law protected by the Court of Justice and that the protection of such rights, whilst inspired by the constitutional traditions common to the Member States, must be ensured within the framework of the structure and objectives of the Community.

According to the Simmenthal judgment, the precedence of Community law applies even with regard to a subsequent national law.

Interactive diagram on the direct effect of secondary Community law, that is, on the possibility for private parties before national courts to rely on rights drawn from regulations, decisions and directives in particular.

The Van Gend & Loos judgment is one of the most important judgments in the development of the Community legal order. The European Court of Justice specifies that the Community constitutes a new legal order of international law for the benefit of which the States have limited their sovereign rights and the subjects of which comprise not only Member States but also their nationals. The Court concludes from this a fundamental principle: that of the direct effect of Community law.

According to the Court of Justice, in its judgment of 16 June 1966, in Case 57/65, Lütticke/Hauptzollamt Saarlouis, an obligation imposed by the Treaty on the Member States, which is not qualified by any condition or subject, in its implementation or effects, to the taking of any measure either by the institutions of the Community or by the Member States, is capable of producing direct effects on the legal relationships between the Member States and persons within their jurisdiction.

According to the Court of Justice, in its judgment of 8 April 1976, in Case 43/75, Defrenne/Sabena, articles of the treaty which are mandatory apply not only to the action of public authorities but also extend to independent agreements concluded privately or in the sphere of industrial relations, such as individual contracts and collective labour agreements.

It emerges from the judgment of the Court of Justice of 6 October 1970, in Case 9-70, Franz Grad v Finanzamt Traunstein, that it would be incompatible with the binding effect attributed to decisions by Article 189 of the EEC Treaty (now Article 249 of the EC Treaty) to exclude in principle the possibility that persons affected may invoke the obligation imposed by a decision before the national courts. Therefore, in each particular case, it must be ascertained whether the nature, background and wording of the provision in question are capable of producing direct effects in the legal relationships between the addressee of the act and third parties.

It emerges from the judgment of the Court of Justice of 19 January 1982, in Case 8/81, Becker, that, even though a directive as a whole has not been implemented, individuals may not for that reason be denied the right to rely on any of its provisions which, owing to their particular subject matter, are capable of being severed from the general body of provisions and applied separately.

In this judgment, the Court recognises the direct effect not only of the provisions of the Treaties (Article 39 –ex Article 48– of the EC Treaty), but also of the directives laid down for their application (Article 3 of Directive No 64/221 of the Council). It interprets the notion of 'public policy' as a justification for derogating from a fundamental principle of Community law: the freedom of movement of workers.

According to the Court of Justice, in its judgment of 18 December 1996, in Case C-129/96, Inter-Environnement Wallonie/Région wallonne, although the Member States are not obliged to adopt the measures necessary to achieve the result prescribed by the Directive on waste before the end of the period prescribed for transposition, it follows from the second paragraph of Article 5, taken in conjunction with the third paragraph of Article 189 of the EEC Treaty (now Articles 249 and 10 of the EC Treaty), and from the directive itself, that, during that period, they must refrain from taking any measures liable seriously to compromise the prescribed outcome.

In its judgment of 26 February 1986, in Case 152/84, Marshall/Southampton and South-West Hampshire Area Health Authority, the Court of Justice points out that, where a person involved in legal proceedings is able to rely on a directive in an action against the State, he may do so regardless of the capacity in which the latter is acting, whether employer or public authority. In either case, it is necessary to prevent the State from taking advantage of its own failure to comply with Community law.

In its judgment of 13 November 1990, in Case C-106/89, Marleasing/Comercial Internacional de Alimentación, the Court of Justice points out that, in applying national law, whether the provisions in question were adopted before or after a directive, the national court called upon to interpret it is required to do so, as far as possible, in the light of the wording and the purpose of the directive in order to achieve the result pursued by the latter and thereby comply with the third paragraph of Article 189 of the EEC Treaty (now Article 249 of the EC Treaty).

In its judgment of 14 July 1994, in case C-91/92, Faccini Dori v Recreb, the Court of Justice concludes that, in the absence of measures of transposition within the prescribed time-limit, an individual may not rely on a directive in order to claim a right against another individual and enforce such a right in a national court.

According to the Court of Justice, in its judgment of 12 March 1996, in Case C-441/93, Pafitis and Others, Article 25 of the Directive on coordination of safeguards which are required by Member States of companies, pursuant to which any increase in capital must be determined by the general meeting, precludes national legislation under which the capital of a bank constituted in the form of a public limited liability company which, as a result of its debt burden, is in exceptional circumstances, may be increased by an administrative measure, without a resolution of the general meeting.

According to the Court of Justice, in its judgment of 30 April 1996, in Case C-194/94, CIA Security International/Signalson and Securitel, Articles 8 and 9 of the Directive laying down a procedure for the provision of information in the field of technical standards and regulations, under which Member States must notify the Commission of all draft technical regulations covered by the Directive and, except in particular urgent cases, suspend their adoption and implementation for specified periods, are to be interpreted as meaning that individuals may rely on them before the national court, which must decline to apply a national technical regulation which has not been notified in accordance with the Directive.

In its judgment of 26 September 2000, in case C-443/98, Unilever, the Court of Justice points out that whilst it is true that a directive cannot of itself impose obligations on an individual and cannot therefore be relied on as such against an individual, that case-law does not apply where non-compliance by a Member State with an article of the directive, which constitutes a substantial procedural defect, renders a technical regulation inapplicable. A national court is thus required, in civil proceedings between individuals concerning contractual rights and obligations, to refuse to apply a national technical regulation which was adopted in breach of the article in question of the directive.

In its judgment of 6 June 2002 in Case C-159/00, Sapod Audic, the Court of Justice points out that, according to established case-law, the Directive laying down a procedure for the provision of information in the field of technical standards and regulations must be interpreted as meaning that a failure to observe the obligation to notify laid down in Article 8 of that Directive constitutes a substantial procedural defect such as to render the technical regulations in question inapplicable and thus unenforceable against individuals. Furthermore, the Court recalls that, according to its case-law, the inapplicability of a technical regulation which has not been notified to the Commission in accordance with Article 8 of the Directive may be invoked in legal proceedings between individuals concerning, inter alia, contractual rights and duties.

According to the Court of Justice, in its judgment of 9 September 2003, in Case C-151/02, Jaeger, the Directive concerning certain aspects of the organisation of working time must be interpreted as meaning that on-call duty performed by a doctor where he is required to be physically present in the hospital must be regarded as constituting in its totality working time for the purposes of that Directive even where the person concerned is permitted to rest at his place of work during the periods when his services are not required, with the result that that Directive precludes legislation of a Member State which classifies as rest periods an employee’s periods of inactivity in the context of such on-call duty.

In its judgment of 5 October 2004, in Joined Cases C-397/01 to C-403/01, Pfeiffer and Others, the Court of Justice concludes that, when hearing a case between individuals, a national court is required, when applying the provisions of domestic law adopted for the purpose of transposing obligations laid down by a directive, to consider the whole body of rules of national law and to interpret them, so far as possible, in the light of the wording and purpose of the directive in order to achieve an outcome consistent with the objective pursued by the directive.

Dans son arrêt du 19 janvier 2010, dans l'affaire C-555/07, Kücükdeveci contre Swedex, la Cour de justice conclut qu’il incombe à la juridiction nationale, saisie d’un litige entre particuliers, d’assurer le respect du principe de non-discrimination en fonction de l’âge, qui est un principe général du droit de l’Union concrétisé par une directive, en laissant au besoin inappliquée toute disposition contraire de la réglementation nationale.