The direct effect principle therefore ensures the application and effectiveness of European law in the Member States. However, the Court of Justice defined several conditions in order for a European legal act to be immediately applicable. In addition, the direct effect may only relate to relations between an individual and a Member State or be extended to relations between individuals.
The direct effect of European law has been enshrined by the Court of Justice in the judgement of Van Gend en Loos of 5 February 1963. In this judgement, the Court states that European law not only engenders obligations for Member States, but also rights for individuals. Individuals may therefore take advantage of these rights and directly invoke European acts before national and European courts. However, it is not necessary for the Member State to adopt the European act concerned into its internal legal system.
There are two aspects to direct effect: a vertical aspect and a horizontal aspect. Vertical direct effect is of consequence in relations between individuals and the State. This means that individuals can invoke a European provision in relation to the State. Horizontal direct effect is consequential in relations between individuals. This means that an individual can invoke a European provision in relation to another individual.
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