The Court of Justice of the European Union has annulled a decision by the European Court of Auditors (ECA) refusing to authorise one of its staff members to give testimony in an investigation by the European Public Prosecutor's Office (EPPO), according to the prosecution service.

The ruling, announced through the EPPO's official communications channel, removes the auditors' block on the testimony. The EPPO did not disclose the case reference, judgment date, or full operative text in its initial notice.

What stands behind the dispute?

The ECA, seated in Luxembourg, audits the financial accounts of the European Union and its institutions. Its auditors and other employees may possess evidence relevant to criminal investigations into EU spending.

The EPPO, also based in Luxembourg, started operations on 1 June 2021 under Council Regulation (EU) 2017/1939. It investigates, prosecutes and brings to judgment perpetrators of offences against the EU budget, including fraud, corruption, and misappropriation of EU funds.

Where the EPPO needs testimony from EU officials, it sends a cooperation request to the institution concerned. That institution can authorise the testimony, decline on limited grounds, or refer the question to the courts. The CJEU acts as the final arbiter where cooperation breaks down.

What did the CJEU decide?

The Court of Justice annulled the ECA's refusal. The annulment sits within Article 263 of the Treaty on the Functioning of the European Union (TFEU), the action by which the CJEU reviews the legality of acts of EU institutions. The annulment restores the situation as if the ECA's refusal had never existed.

Under the operative effect of such a judgment, the ECA must re-examine the EPPO's request and reach a new decision. That decision must comply with the legal reasoning in the CJEU ruling. The Court of Justice does not substitute itself for the ECA; it returns the matter to the auditors.

Which legal framework applied?

The ECA's refusal sits within the EU Staff Regulations, the body of rules governing EU officials. Article 19 of those regulations protects officials from disclosing information obtained in the course of duties, except where EU law requires disclosure. The Court had to weigh that protection against the EPPO's cooperation rights under Regulation 2017/1939.

The full reasoning of the Court will appear in the published text of the judgment. The prosecution office's announcement did not include the date of the hearing, the date of delivery, or the panel composition.

What does the ruling change for practitioners?

The decision tightens the duty to cooperate between the ECA and the EPPO. An auditors' court cannot rely on internal rules of staff conduct to obstruct testimony in a criminal investigation by the EU prosecutor.

The ruling also confirms the judicial-review pathway: where one EU institution blocks cooperation with another, the blocked party can bring an action directly before the CJEU. This pathway was already available under Article 263 TFEU; the ruling confirms it can produce a binding annulment on the facts.

For criminal practitioners, the decision removes a practical obstacle. Investigators at the EPPO can now expect testimony from ECA officials on matters touching EU budget execution. Auditors who possess direct knowledge of programmes under investigation no longer face an institutional gate before speaking.

What happens next?

The ECA must revisit the request. It can comply, adopt a second refusal that addresses the Court's reasoning, or seek interim measures from the CJEU. The EPPO did not announce a procedural timetable. The underlying criminal investigation remains confidential under the EPPO's procedural rules.

The decision shows the Court of Justice willing to police the boundaries of cooperation between EU institutions in criminal matters. It draws a line on the reach of internal staff rules where those rules cut across the EPPO's prosecutorial mandate.