European arrest warrant after acquittal: double prosecution and detention

Protection against renewed prosecution or punishment for the same acts already finally adjudicated is afforded by the prohibition of double prosecution, known as ne bis in idem. Within the Union, Art. 50 of the EU Charter of Fundamental Rights establishes this protection. In Austrian surrender proceedings, §§ 7, 8 and 8a EU-JZG distinguish between an Austrian decision, cases covered by Art. 54 of the Convention Implementing the Schengen Agreement (CISA), and decisions outside that scope. Even though no sentence was enforced, a final acquittal can provide protection under CISA, since the additional enforcement condition applies to convictions. Austria does not conduct a new trial to decide whether the earlier acquittal was correct on its merits. Using the relevant decision, it examines the requirements for refusing surrender.

The actual conduct, rather than its legal classification alone, is the subject of the assessment. Consequently, a different offence heading in the new warrant does not itself create different acts. Conversely, identity is not established by the same victim or a similar period. The individual actions, locations, periods, participants and events must be compared as a connected factual situation. Where the earlier judgment covers only some of several actions, the defence must precisely identify the protected part. Both overlaps and additional allegations are revealed by setting the allegations in the warrant alongside the operative part and findings of the earlier decision.

The law of the state that issued a decision initially determines whether that decision finally ends prosecution. Merely filing a case away or provisionally ending proceedings is insufficient for cross-border protection. In principle, a prosecutorial decision can qualify, and its reasons and the preceding examination of the merits matter. In C-486/14, Kossowski, dated 29 June 2016, the CJEU clarified that, in the circumstances described there, a final discontinuance without a detailed investigation did not amount to a final decision on the merits under Art. 54 CISA. This does not exclude every discontinuance for insufficient evidence. The complete reasons, evidence of finality and, where necessary, information from the competent foreign authority are needed.

Where a final Austrian decision concerning the same acts can be set aside only under the conditions for ordinary reopening and prevents further prosecution in the issuing state, enforcement is in any event inadmissible under § 7 Abs. 1 EU-JZG. The additional situations in § 7 Abs. 2 must be distinguished: where Austrian criminal law applies to the acts, domestic proceedings or a prosecutorial decision ending proceedings may be relevant. However, § 7 Abs. 3 provides exceptions to subsection 2 for people without Austrian citizenship, including where the foreign proceedings should take priority or proceedings ended for insufficient evidence. Those exceptions must not be applied indiscriminately to the final decision covered by subsection 1.

Enforcement of the European arrest warrant is prohibited by § 8 EU-JZG if such enforcement would breach the protection under Art. 54 CISA. Following a conviction, Art. 54 requires, in addition to the same acts and final adjudication, that the penalty has been enforced, is being enforced, or can no longer be enforced under the law of the sentencing state. Therefore, a final criminal judgment alone does not answer this additional question. A current enforcement certificate, sentence calculation, and decisions about legal enforceability can help. Without examination, pre-trial detention must not be treated as complete enforcement of the sentence. The documents must show which penalties the judgment imposes and which have already been dealt with.

Expressly separated since 1 November 2025 are § 8 and § 8a EU-JZG. Final adjudication by a state not bound by Art. 54 CISA, the International Criminal Court or another international court is covered by § 8a. In this situation, enforcement may be declared inadmissible. The provision additionally refers to enforcement of the sentence or preventive measure and requires that renewed prosecution or enforcement is not called for in the interests of justice or for reasons of individual and general prevention. Therefore, this route does not provide automatic refusal on the model of § 8. Specifically, it must be checked whether the state that issued the decision is bound by Art. 54 CISA; EU membership and the application of CISA are not interchangeable concepts.

The complete European arrest warrant with a comprehensible translation, the earlier judgment or discontinuance decision with its reasons, and reliable evidence that it is final form the initial set of documents. The indictment and earlier descriptions of the acts help establish the extent of the matter already adjudicated. Include enforcement records following a conviction. Austrian detention and surrender decisions show which issues have already been decided. If the information is insufficient for the surrender decision, Art. 15(2) of Framework Decision 2002/584/JHA provides for the urgent request of necessary supplementary information from the issuing state. Case references and authority contact details can be collected by relatives. Send sensitive criminal case files only after an appropriate transmission method has been agreed with the firm.

Specifically in the Austrian surrender proceedings, the double-prosecution objection should be raised by the defence, and the supporting documents should be submitted. At the same time, the current detention decision must be examined: § 18 Abs. 2 EU-JZG refers to the corresponding application of § 29 ARHG and thus, in principle, the pre-trial detention rules. Grounds for detention, proportionality and less restrictive measures remain separate issues. An alleged obstacle to surrender does not itself terminate detention. In 14 Os 118/26y of 7 October 2026, objections to the admissibility of surrender were likewise distinguished by the Austrian Supreme Court from the questions relevant to the particular detention remedy. Using the decisions served and their appeal instructions, surrender and detention remedies should be coordinated. Any other independent basis for detention requires additional examination.