Short answer
Any national court may ask the Court of Justice for a preliminary ruling when an answer on the interpretation or validity of EU law is necessary to decide a case. A final national court must refer if an EU-law interpretation or validity question is necessary to decide the case.
There are three recognised situations in which that final court need not refer. The EU-law question may be irrelevant to the outcome. The Court of Justice may already have interpreted the point—often called acte éclairé. Or the correct interpretation may be so obvious that there is no reasonable doubt—acte clair. That last exception is demanding: the court must assess the provision in its multilingual and EU-law context and consider the risk of divergent decisions. A party cannot compel a reference merely by asking for one. But when a final court declines to refer, its reasons must identify specifically and concretely which of the three situations applies.
Article 267 separates a power from a duty
Article 267 of the Treaty on the Functioning of the European Union (TFEU) allows the Court of Justice to give preliminary rulings on Treaty interpretation and on the validity and interpretation of EU institutional acts. Its second and third paragraphs draw the key distinction:
Where such a question is raised before any court or tribunal of a Member State, that court or tribunal may, if it considers that a decision on the question is necessary to enable it to give judgment, request the Court to give a ruling thereon.
Where any such question is raised in a case pending before a court or tribunal of a Member State against whose decisions there is no judicial remedy under national law, that court or tribunal shall bring the matter before the Court. —
Referral is a power for a court not deciding at final instance. For the final court, “shall” creates a duty, subject to the limited situations below.
The test is functional. In Lyckeskog, Case C-99/00, a Swedish court was not final merely because further appeal required permission: the supreme court could grant leave and refer.
The question must matter to the judgment
Even a final court first decides whether the EU-law issue is necessary. If the answer cannot affect the outcome, no reference is required. The process is cooperation between courts, not an appeal route controlled by the parties: the court decides necessity and formulates any question. In Consorzio Italian Management and Catania Multiservizi, Case C-561/19, the Grand Chamber also accepted that a final court may reject an inadmissible plea under national rules that respect equivalence and effectiveness.
When existing authority is acte éclairé
The first substantive exception is acte éclairé: the Court of Justice has already supplied the interpretation needed to resolve the point.
In Da Costa en Schaake and Others, Joined Cases 28 to 30/62, the Court held that an earlier ruling on a materially identical question can remove the purpose of the duty. CILFIT and Others, Case 283/81, added that existing decisions may resolve the point even where the questions are not strictly identical.
The legal point must genuinely be resolved; factual resemblance is not enough. If the earlier judgment's scope is uncertain or later law creates a new difficulty, the court remains free—and may be required—to refer again.
Acte clair means no reasonable doubt
The second substantive exception is acte clair. It is not enough that the final court considers one reading better than another. CILFIT set the standard:
Finally, the correct application of Community law may be so obvious as to leave no scope for any reasonable doubt as to the manner in which the question raised is to be resolved. Before it comes to the conclusion that such is the case, the national court or tribunal must be convinced that the matter is equally obvious to the courts of the other Member States and to the Court of Justice. —
Clarity must be assessed through EU law's own characteristics. Its legislation has multiple equally authentic languages, its terms may have autonomous meanings, and each provision must be read in its wider context, objectives, and state of development. Consorzio clarifies that the court need not examine every official language version, but must consider verified divergences of which it is aware. Not every imaginable alternative creates doubt: a competing interpretation must be sufficiently plausible in the provision's context and purpose.
Conflicting decisions are a warning, not an automatic rule
Conflicting national judgments do not mechanically require a reference. A final court may find that lower courts are wrong and the EU-law answer remains obvious. But disagreement is evidence of interpretive difficulty and a risk of divergent application.
In Ferreira da Silva e Brito and Others, Case C-160/14, lower courts had reached conflicting decisions on the meaning of a “transfer of a business”, and the concept had repeatedly caused difficulties across Member States. The Court of Justice held that the Portuguese court of last instance was required to refer. It stressed the systemic concern:
That uncertainty shows not only that there are difficulties of interpretation, but also that there is a risk of divergences in judicial decisions within the European Union. —
Conflicting authority across Member States or on an autonomous EU concept makes acte clair harder to sustain.
A final court must explain why it did not refer
The decision not to refer is not complete when it merely invokes CILFIT. Reading Article 267 TFEU with the right to a fair hearing in Article 47 of the Charter, Consorzio required the judgment's reasons to identify the actual basis. The Grand Chamber made that requirement more concrete in Remling, Case C-767/23:
where such a court decides not to refer the matter to the Court under one of those exceptions, that decision must, in all cases, comply with the requirement to state reasons … namely to set out, specifically and concretely, the reasons why that exception applies. —
A reasoned decision must show which exception applies. It may be succinct where the issue cannot affect the outcome. A case citation may suffice where the questions are materially identical; less direct authority may require more explanation. For acte clair, the court must normally address plausible competing interpretations, known language differences, and conflicting case law.
The obligation does not depend on an express request. Under Remling, it applies when a party raises EU law and when the final court must or may raise a binding EU-law issue of its own motion. The court may adopt adequate lower-court reasons, but a bare summary dismissal is insufficient.
In Centro Petroli Roma, Case C-386/24, the Court confirmed in June 2026 that the explanation need not prove in detail that every other final court and the Court of Justice would agree. It must still explain why the answer would be equally obvious to them, having regard to EU law's characteristics and the risk of divergence.
An earlier reference in the same national case does not automatically discharge the duty. If a further necessary interpretive question remains after the Court's ruling, the final court must apply the same three-part test again.
Interpretation and validity must be kept separate
The acte clair and acte éclairé exceptions concern interpretation. A national court may reject an invalidity argument, but it may not itself declare an EU act invalid. If it considers a necessary validity challenge well founded, it must refer that issue to the Court of Justice.
A practical reference checklist
A national court can work through the duty in this order:
- Is there an EU-law issue? Identify the provision, applicable version, and whether interpretation or validity is disputed.
- Can the answer affect the judgment? If not, the question is irrelevant.
- Is this court final in these proceedings? Examine the available judicial remedy, including any leave-to-appeal process.
- Has the Court resolved the legal point? Check the reasoning and later developments, not just factual similarity.
- If not, is there truly no reasonable doubt? Consider language, autonomous terminology, context, objectives, legal evolution, and plausible competing readings.
- Is there conflicting case law? Assess its seriousness and the risk of divergent application.
- If no reference is made, are the reasons explicit? State irrelevance, existing authority, or the basis for acte clair.
Conclusion
A final national court must refer when an EU-law interpretation is necessary and the point is neither already resolved nor free from reasonable doubt. Other national courts retain a broad power to refer necessary questions.
Acte éclairé applies when Court authority genuinely answers the point. Acte clair applies only after an EU-specific assessment leaves no reasonable doubt. Neither is a shortcut based on confidence or convenience. A final court that does not refer must identify the lawful basis in its reasons.
Sources
This article provides general legal information, not advice for a specific matter. Laws, facts and procedural deadlines may change the result. Follow the linked primary sources and obtain local advice before acting.