What is horizontal direct effect in relation to directives?

Horizontal direct effect refers to the principle in EU law that allows individuals to invoke certain rights conferred by EU directives against other private parties, not just against the state or public authorities. This contrasts with vertical direct effect, where individuals can rely on directives only when dealing with the state.

When a directive is intended to create rights for individuals, horizontal direct effect means that if a private party fails to implement the directive correctly or does not respect the rights it creates, individuals can take action against them. This ensures that individuals can seek remedies for their rights, reinforcing the effectiveness of EU law across all levels of society, not just in interactions with state entities.

The other options pertain to different aspects of the interaction between EU law and domestic law. For example, directives being applied only to government bodies misrepresents the broader implications of horizontal direct effect. Enforcement of rights solely within domestic law does not encapsulate the EU framework's intent behind establishing individual rights and responsibilities across borders. Finally, if directives were to apply only to private entities, it would negate the comprehensive approach intended by EU law to ensure that rights are protected in all contexts, thereby limiting the intended scope of individual entitlements under EU directives.