Costa v. ENEL (1964): Establishing the Principle of EU Law Supremacy

“National law cannot stand above the Treaties. EU law prevails.” This firm declaration is the essence of the Costa v. ENEL judgment.

Hello, readers interested in European law. Today we’ll look at Costa v. ENEL (1964). When I first encountered this case, I wondered, “Can anything really take precedence over domestic law?” This decision established that European Union (EU) law is not merely an inter-state agreement but a new legal order that stands above the laws of the Member States. Following Van Gend en Loos and its principle of direct effect, this case set the second pillar of the EU legal order: the supremacy (primacy) of EU law.

Contents

Background and Facts Core Issue: Supremacy of EU Law The Court’s Decision and Reasoning Impact on the EU Legal Order Criticism and Scholarly Debate Contemporary Significance and Takeaways

Background and Facts

Italian citizen Flaminio Costa was a lawyer and small-scale electricity consumer. He refused to pay part of his electricity bill to the newly established state-owned utility ENEL, arguing that Italy’s nationalization law conflicted with the then EEC Treaty. The Italian court intended to dismiss the claim, but the matter was referred to the Court of Justice of the European Union (CJEU).

Core Issue: Supremacy of EU Law

The issue was simple yet revolutionary: When domestic law conflicts with the EEC Treaty, which prevails?

Side	Claim	Core Reasoning
Costa	EU law supremacy	The nationalization statute violates the EEC Treaty and should be disapplied domestically.
Italian Government	Domestic law supremacy	National law expresses state sovereignty and should prevail within the domestic legal order.

The Court’s Decision and Reasoning

The CJEU sided with Costa and established the principle of EU law supremacy (primacy). The core reasoning was:

• The Treaties created a new legal order that limits Member States’ sovereign powers.
• Since powers were voluntarily transferred to the EU, subsequent domestic laws cannot conflict with the Treaty.
• If domestic law were to prevail, Member States could neutralize EU law at will, rendering the integration project meaningless.

Impact on the EU Legal Order

Costa v. ENEL articulated the principle of legal supremacy, placing EU law above domestic law. EU Treaties and regulations thus became top-tier norms with direct binding force in national legal systems. Alongside Van Gend en Loos (direct effect), this case elevated the EU legal order to a constitutional plane.

Criticism and Scholarly Debate

While widely welcomed as a strong legal statement, the ruling also provoked tensions with national constitutional orders. Germany and Italy’s constitutional courts, in particular, have been cautious about recognizing absolute supremacy. The debate splits roughly as follows:

Viewpoint	Main Argument
Critical	Judicial activism disregards national constitutional identity and undermines sovereignty.
Supportive	Since Member States voluntarily transferred powers, supremacy is essential to preserve the integrated legal order.

Contemporary Significance and Takeaways

Costa v. ENEL remains a textbook case in EU law because it provides the standard for courts when national law clashes with EU law. In short, its significance is:

• A historic declaration of the supremacy of EU law.
• Together with Van Gend en Loos, it completes the foundation of the EU legal order by coupling direct effect with supremacy.
• It launched an ongoing dialogue—and occasional tension—with national constitutional courts over identity and fundamental rights.

Frequently Asked Questions (FAQ)

Q What was Costa v. ENEL about?

An Italian lawyer, Costa, argued that the nationalization of the electricity industry violated the EEC Treaty, raising the conflict between national law and EU law.

Q What was the core issue?

When national law conflicts with the EEC Treaty, which should prevail?

Q How did the CJEU rule?

EU law prevails over national law; Member States may not apply legislation that conflicts with the Treaties.

Q What is the “supremacy (primacy) of EU law”?

EU law takes precedence over all Member States’ domestic law, and national courts must apply EU law first in case of conflict.

Q What was the broader impact?

It constitutionalized the EU legal order by giving EU law direct binding force and priority within national legal systems.

Q Is it still cited today?

Yes. Costa v. ENEL is still frequently cited as the foundational case establishing the supremacy of EU law.

In Closing

Costa v. ENEL (1964) built the second pillar—supremacy—on top of the first—direct effect—to complete the EU legal architecture. I like to imagine a judge reaching for a compass whenever national law and EU law collide: Apply EU law first, and ensure its practical effectiveness in national courts. Keep those two lines in mind, and tricky cases become clearer. If you’re stuck on tensions with national constitutions, fundamental rights review, or order of application, share a scenario—we can walk through where the priority flips. 🙂