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Chapter 5 of 8

How Does EU Law Apply at Home? Supremacy, Direct Effect, and National Courts

EU law does not stay in Brussels—it reshapes national legal systems every day. This module shows how doctrines like supremacy and direct effect give EU rules real teeth in domestic courts, and why this sometimes triggers constitutional tensions.

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1. From Brussels to Your Local Court

EU Law in Daily Life

EU law affects real cases in national courts: traffic fines, consumer rights, data protection, and more. It is not just something that happens in Brussels or Luxembourg.

Key Question

The core question here is: how does EU law actually work inside each Member State’s legal system and in front of local judges?

Three Core Doctrines

Three ideas make EU law effective at home: direct effect, supremacy (also called primacy), and the role of national courts as EU law courts working with the CJEU.

Built by Case Law

These doctrines are mostly not spelled out in one treaty article. They were created and refined by the Court of Justice through case law from the 1960s to today.

2. Direct Effect: Can I Rely on EU Law in Court?

What Is Direct Effect?

Direct effect asks: can an individual rely directly on an EU rule in a national court, in the same way they rely on a domestic statute?

Van Gend en Loos (1963)

In Van Gend en Loos, the CJEU said the EU is a new legal order and that some treaty rules give rights to individuals that national courts must protect.

Conditions for Direct Effect

An EU rule has direct effect if it is clear and precise, unconditional, and complete enough to be applied by a court without extra rules.

Which EU Rules?

Treaty articles, regulations, and some directive provisions can have direct effect, as long as they meet those conditions. Directives, however, have special limits.

3. Vertical and Horizontal Direct Effect

Vertical vs Horizontal

Vertical direct effect is using EU law against the state. Horizontal direct effect is using EU law against another private person or company.

Treaties and Regulations

Treaty provisions and regulations can usually have both vertical and horizontal direct effect if they are clear, precise, and unconditional.

Directives: No Horizontal Effect

Directives do not have horizontal direct effect. You generally cannot rely on a directive alone to claim rights against a private party.

Directives: Vertical Effect

Once the implementation deadline has passed, clear rules in a directive can be relied on against the state or public bodies: this is vertical direct effect.

Workarounds

To protect individuals, the CJEU uses indirect effect (interpret national law in line with directives) and state liability, without overturning the no-horizontal-effect rule.

4. Example: Can I Use a Directive Against My Employer?

The Scenario

An EU Working Time Directive limits weekly hours. Your country implements it badly. You work 60 hours a week and want to rely on the directive.

Public Employer

If you work for a state‑owned hospital, it is an emanation of the state. You can rely on the directive directly against this public employer: vertical direct effect.

Private Employer

If you work for a private delivery company, you cannot rely directly on the directive against it: directives have no horizontal direct effect.

What Courts Can Still Do

The court must interpret national law in line with the directive where possible and you may claim damages from the state if its failure to implement caused you loss.

5. Supremacy (Primacy): What If EU Law Conflicts with National Law?

What Is Supremacy?

Supremacy or primacy means that EU law has priority over any conflicting national law, including constitutions and ordinary statutes.

Why Supremacy?

Member States gave powers to the EU by treaty. In those areas, EU rules must prevail or the EU legal system would not function effectively.

How It Works in Court

If a national rule conflicts with EU law, the judge must disapply the national rule in that case and apply EU law instead. The rule is not erased, but it is ignored for that conflict.

Status Today

Supremacy is not in one treaty article, but it is recognised in a Lisbon Treaty declaration and in long‑standing CJEU case law up to 2026.

6. Example: Speed Limits and Supremacy

The Conflict

EU regulation sets a 120 km/h limit. A later national law allows 140 km/h on the same roads. You are fined for driving 135 km/h.

Judge’s Task

The judge checks that the EU regulation applies, sees the conflict, and must disapply the national 140 km/h rule because of EU supremacy.

Outcome

Your speed still breaks the EU 120 km/h limit, so the fine stands, but it is now based on EU law, not on the conflicting national law.

Key Lesson

Supremacy applies even if the national law is newer. In any conflict, valid EU law wins in that case.

7. National Courts as EU Law Courts and Preliminary References

National Courts as EU Courts

National judges are also EU law judges. They apply EU rules and use doctrines like direct effect and supremacy in everyday cases.

Article 267 TFEU

The preliminary reference procedure lets national courts ask the CJEU how to interpret or check the validity of EU law.

How a Reference Works

The national court pauses the case, sends its EU law question to the CJEU, receives an answer, then resumes the case and applies that interpretation.

Who Can Refer?

Any court can refer. Courts of last instance are usually obliged to refer if the EU law question is necessary to decide the case and is genuinely unclear.

8. Constitutional Tensions and Practical Limits

Why Tension?

National constitutional courts accept EU primacy but often add a condition: EU law must respect core constitutional values like human dignity and democracy.

Recent Clashes

Germany’s court has warned it may review EU acts for overstepping powers, while Poland’s tribunal has declared some EU law incompatible with its constitution.

CJEU’s View

For the CJEU, supremacy is unconditional: national courts must apply EU law even if a national constitution says the opposite.

Everyday Reality

Most of the time, courts avoid open conflict, use careful interpretation, and cooperate through preliminary references, but the underlying tension remains.

9. Thought Exercise: Putting It All Together

Work through these short scenarios. For each one, decide:

  1. Does the EU rule likely have direct effect?
  2. Is the situation vertical or horizontal?
  3. Does supremacy matter here?

Write down your answers in three columns (Direct Effect? Vertical/Horizontal? Supremacy?).

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Scenario A: Data Protection and a Social Media Platform

  • The GDPR (an EU regulation on data protection) gives users clear rights over their personal data.
  • You sue a large private social media company in your national court, claiming it violated your GDPR rights.

Questions:

  • Can you rely directly on GDPR provisions in court?
  • Is this vertical or horizontal?
  • Is there any conflicting national law that supremacy would affect?

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Scenario B: Environmental Directive and a Local Authority

  • An EU directive requires Member States to set strict limits on air pollution.
  • Your country missed the deadline and has weak national rules.
  • You sue your city council (a public authority) for failing to keep pollution within the EU limits.

Questions:

  • Can you rely directly on clear provisions of the directive?
  • Vertical or horizontal?
  • How does supremacy influence the judge’s approach to the weak national rules?

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Scenario C: Consumer Rights and a Shop’s Contract Terms

  • An EU directive on unfair contract terms says certain clauses in consumer contracts are invalid.
  • Your country implemented it, but the national law is ambiguous.
  • You challenge an unfair clause in a contract with a private shop.

Questions:

  • Can you rely directly on the directive against the shop?
  • If not, what tools does the court still have (think indirect effect, interpretation, maybe state liability)?
  • Does supremacy play a role if the national implementing law seems weaker than the directive?

After you answer, compare your reasoning against the core rules from earlier steps and adjust any misunderstandings.

10. Quick Check: Core Concepts

Test your understanding of direct effect, supremacy, and national courts.

Which statement best describes the current relationship between EU law and national law in Member States?

  1. EU law has supremacy over all conflicting national law within its fields of competence, and national courts must disapply conflicting national rules in concrete cases.
  2. National constitutions always override EU law, so EU rules only apply when they do not conflict with constitutional provisions.
  3. EU law and national law are equal; if they conflict, the newer rule (EU or national) automatically wins.
Show Answer

Answer: A) EU law has supremacy over all conflicting national law within its fields of competence, and national courts must disapply conflicting national rules in concrete cases.

The CJEU’s doctrine of supremacy means that valid EU law prevails over any conflicting national law in areas where the EU has competence. National courts must disapply the conflicting national rule in the specific case. Some constitutional courts contest this in theory, but doctrinally option 1 is correct.

11. Flashcards: Key Terms Review

Use these cards to review the main ideas from this module.

Direct effect
A doctrine allowing individuals to rely directly on certain EU law provisions before national courts, when those provisions are clear, precise, unconditional, and complete enough to apply.
Vertical direct effect
Use of an EU law provision by an individual against the state or a public body (an emanation of the state). Directives can have vertical direct effect once properly triggered.
Horizontal direct effect
Use of an EU law provision by one private party against another private party. Treaties and regulations can have this; directives, as a rule, cannot.
Supremacy (primacy) of EU law
The principle that, in case of conflict, valid EU law takes priority over any national law, including constitutions, and national courts must disapply the conflicting national rule in that case.
Preliminary reference (Article 267 TFEU)
A procedure where a national court asks the CJEU to interpret EU law or rule on its validity, then applies that answer to resolve the national case.
Indirect effect
The obligation on national courts to interpret national law, as far as possible, in a way that is consistent with EU law, especially directives that lack horizontal direct effect.
State liability
A doctrine requiring Member States to compensate individuals for damage caused by serious breaches of EU law, such as failure to implement a directive (Francovich principle).
Emanation of the state
A body that, although distinct from the state, is under its control or performs a public service with special powers, so that directives can have vertical direct effect against it.

Key Terms

Direct effect
Doctrine allowing individuals to invoke certain EU law provisions directly before national courts, if they are clear, precise, unconditional, and judicially complete.
Indirect effect
Duty of national courts to interpret domestic law as far as possible in conformity with EU law, especially directives lacking horizontal direct effect.
State liability
EU law principle that Member States must compensate individuals for loss caused by serious breaches of EU law, such as not implementing directives on time.
Article 267 TFEU
Treaty provision establishing the preliminary reference procedure between national courts and the CJEU.
Preliminary reference
Procedure under Article 267 TFEU where national courts ask the CJEU to interpret EU law or assess its validity, to ensure uniform application across the EU.
Emanation of the state
An organisation under state control or performing a public service with special powers, treated like the state for vertical direct effect of directives.
Vertical direct effect
Direct effect used by an individual against the state or a public body, including emanations of the state.
Horizontal direct effect
Direct effect used by one private party against another private party; available for treaties and many regulations, but generally not for directives.
Supremacy (primacy) of EU law
Principle that valid EU law prevails over conflicting national law in areas of EU competence, requiring national courts to disapply conflicting national rules in specific cases.
CJEU (Court of Justice of the European Union)
The EU’s highest court for interpreting EU law and ensuring its uniform application across Member States.

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