By Amara Osei

The European Public Prosecutor's Office has appealed to the Court of Justice of the European Union, contesting the European Court of Auditors' refusal to cooperate in a criminal investigation. The appeal places two EU institutions in open conflict. One of them audits the Union's accounts. The other prosecutes its crimes.

The dispute is institutional, not merely procedural. At stake is whether the EU's financial watchdog can decline to assist the body created specifically to investigate and prosecute criminal offences against the Union's financial interests. The EPPO says no. The auditors, it appears, disagree.

What is the dispute about?

The European Public Prosecutor's Office is the independent prosecution office of the European Union. It investigates fraud, corruption and other criminal conduct affecting EU funds, working alongside national prosecutors across member states. Its investigative powers depend, in practice, on cooperation from other EU bodies — including those that hold the financial records.

The European Court of Auditors, based in Luxembourg, examines the legality and regularity of EU revenue and expenditure. Its archives are, self-evidently, of interest to anyone investigating financial crime within the Union's institutions.

According to the appeal now before the Court of Justice, the Court of Auditors refused to cooperate in an EPPO criminal investigation. The refusal prompted the appeal. The details of the underlying investigation have not been disclosed. Neither has the precise legal ground on which the auditors declined.

What does the appeal ask the Court to decide?

The EPPO has asked the Court of Justice of the European Union to rule on the refusal. The core question is straightforward: can an EU institution lawfully withhold cooperation from a criminal investigation conducted by the EPPO, or does the prosecution office's mandate oblige other bodies to assist?

The answer will shape how future investigations into EU financial crime proceed. A ruling favouring the EPPO would confirm that cooperation obligations bite. A ruling favouring the auditors would carve out an institutional exception — and hand every investigated body a template for resistance.

Why does this matter for practitioners?

For lawyers advising EU institutions, agencies and contractors, the case will clarify the boundaries of the EPPO's coercive reach inside the Union's own apparatus. For defence counsel, the outcome may open or close avenues to challenge evidence obtained through — or withheld by — institutional cooperation.

The case also tests the architecture of EU accountability. The EPPO was designed as an independent prosecution office with real teeth. Those teeth now meet an institution that audits roughly the entirety of the Union's budget. Someone will blink.

What happens next?

The Court of Justice will hear the appeal in due course. A judgment will follow in the ordinary course of the EU's judicial calendar — typically a matter of well over a year from filing, though no date has been announced. Until then, the refusal stands, and the investigation proceeds under a cloud of institutional friction.

The takeaway: the EU's prosecutor and the EU's auditor disagree about who must cooperate with whom, and only the Court of Justice can settle it.