Horizontal direct effect Horizontal direct effect is a legal doctrine developed by the European Court of Justice (ECJ) whereby individuals can rely on the direct effect of provisions in the Treaties, which confer individual rights, in order to make claims against other private individuals before national courts. By virtue of the doctrine of the ‘direct effect’ of Treaty provisions, individuals can rely directly on EC law before their national courts. There is no need for implementation of EC law by Member States through national law.
The ECJ’s creation of the doctrine was driven by Member States’ failure to comply with EC law. The initial rationale of ‘direct effect’ – to secure the effectiveness (‘effet utile’ in French) of EC law by enabling individuals to rely on EC law against Member States that fail to implement or comply with EC law (vertical direct effect) – was then extended to allow individuals to rely on Treaty provisions against other private individuals also: for example, requiring respect for the principle in Article 141 EC of equal pay for women and men (Defrenne v. Sabena, Case 43/75).
The initial rationale of ‘direct effect’ was partially changed when the question arose of the direct effect of directives. The Court held that the doctrine of direct effect did apply to directives. However, directives had only ‘vertical’ direct effect; that is, they could be relied on only vis-a-vis a Member State. Therefore, individuals could only claim the rights conferred by directives against the state or emanations of the state . This more limited version of the doctrine prevented individuals claiming rights under the directive as against other private actors (‘horizontal’ direct effect).
However, the state may appear in a number of emanations of public authority. The scope of the ‘different emanations of the state’ depends on the criteria developed by the European Court to define them (Foster v. British Gas, Case C-188/89,  ECR I-3313). Nonetheless, the rule of horizontal direct effect remains that directives do not have direct effect against private individuals. A number of Opinions by Advocates-General have attempted to overturn the limitation in the doctrine of horizontal direct effect, extending the effect of directives to private persons, but without success (Dori v.
Recreb srl, Case C-91/92,  ECR I-3325). The European Court’s doctrine of indirect effect achieves, partially, the result obtainable through the rule of direct effect; however, this result is obtainable as far as the national law is not wholly inconsistent with Community law. The impact of the doctrine of horizontal direct effect, when applied to provisions of the Treaties, has been limited in the fields of employment and industrial relations, since relatively few Treaty provisions confer individual rights in those areas.
However, the Charter of Fundamental Rights of the European Union has been incorporated as Part II of the Treaty establishing a Constitution for Europe, following a decision of the Intergovernmental ‘Convention on the Future of Europe. ’ The inclusion of fundamental rights concerning employment and industrial relations into the EU Constitutional Treaty, as was the case with equal pay for women and men (Article 141 EC), could lead the ECJ to attribute binding ‘direct effect’, vertical and horizontal, to provisions of the Charter. Vertical direct effect
Vertical direct effect is a legal doctrine developed by the European Court of Justice which allows private individuals to rely directly on Treaty provisions and EU directives in claims against the state before national courts (NV Algemene Transporten Expeditie Onderneming van Gend en Loos v. Nederlandse Administratie der Belastingen, Case 26/62). Insofar as Treaty provisions relating to employment and industrial relations were limited, the doctrine was relatively insignificant. However, where such provisions did exist, as in the provision on equal pay between women and men in Article 141 EC, the impact was substantial.
Moreover, when the Court held that the doctrine of vertical direct effect applied also to the substantial body of EU legal measures in the form of directives (Van Duyn v. Home Office (No. 2)  ECR 1337), the implications were much greater for the field of employment and industrial relations. Employment rights contained in directives now became capable of direct enforcement against the state before national courts. Moreover, directives could be given direct effect against the state in its many forms of public authority.
The scope of the doctrine of vertical direct effect as applied to emanations of the state depends on the criteria developed by the European Court to define these emanations (Foster v. British Gas, Case C-188/89). The criteria laid down could include privatised industries or services that formerly provided public services. Employees in these industries and services may rely directly on provisions in EU directives, so that a large proportion of the national workforce can directly enforce rights contained in EU directives.