TPF, 05.03.2026, RR.2025.118, RR.2025.45
Facts
As part of an investigation into a cyberattack against a French company, judicial authorities in Paris identified A., a resident of Switzerland, as the holder of a cryptocurrency wallet suspected of being used to launder funds of criminal origin. On March 25, 2021, the Paris Public Prosecutor's Office submitted a request for mutual legal assistance to Switzerland, seeking financial information on A., a search of his home to seize data storage devices, and his interrogation.
The Federal Office of Justice delegated the execution of the request to the Public Prosecutor's Office of Basel-Landschaft. On October 26, 2021, a search was conducted at A.'s home, during which numerous data storage devices (phones, computers, hard drives) and paper documents were seized. Following analysis by the cantonal police, a list of items deemed relevant to the French investigation was compiled.
In a closing decision dated July 17, 2025, the Public Prosecutor's Office of Basel-Landschaft authorized the transfer to French authorities of forensic copies of several electronic devices, handwritten notes (notably containing passwords or seed phrases), and Swiss police reports.
A. filed an appeal against this decision with the Appeals Chamber of the Federal Criminal Court, requesting the annulment of the closing decision and the refusal of mutual assistance. He also requested the granting of free legal aid.
Law
The Appeals Chamber notes that cooperation between Switzerland and France is governed by the European Convention on Mutual Assistance in Criminal Matters (ECMA), its protocols, the bilateral Franco-Swiss agreement, the Convention on Cybercrime, and, subsidiarily, by the Federal Act on International Mutual Assistance in Criminal Matters (IMAC).
The Court examines three main legal grievances raised by the appellant:
- The principle of ne bis in idem (art. 66 IMAC): This principle prohibits a person from being prosecuted or tried twice for the same facts. Art. 66 para. 1 IMAC provides that mutual assistance may be refused if criminal proceedings for the same facts are already pending in Switzerland against the person concerned who resides there. However, art. 66 para. 2 IMAC specifies that mutual assistance may nevertheless be granted if the proceedings abroad target other persons or if the execution of the request is likely to exonerate the person being prosecuted.
- Chain of custody and admissibility of evidence: The question of the integrity of the chain of custody and the admissibility of evidence collected in Switzerland falls under the jurisdiction of the trial judge in the requesting state (in this case, France). The person concerned cannot invoke Swiss procedural rules (Criminal Procedure Code) to challenge the admissibility of evidence in foreign proceedings.
- The principle of proportionality and the duty to cooperate: The mutual assistance authority must ensure that there is a sufficient link between the information transmitted and the foreign investigation. However, it is the responsibility of the person affected by the measure to cooperate in the sorting of documents. They must indicate clearly, precisely, and with justification which specific documents are irrelevant or protected by privilege. If they fail to do so in the first instance, relying only on general objections, they forfeit their right to raise this grievance in the appeal proceedings.
Application to the specific case
The Appeals Chamber rejects the appellant's three arguments:
- Regarding the principle of ne bis in idem: Although proceedings are pending against the appellant in Zurich, the Court notes that the French investigation does not target him exclusively. It also concerns other individuals, notably the alleged perpetrators of the cyberattack. Consequently, the exception under art. 66 para. 2 IMAC applies, and the existence of parallel proceedings in Switzerland does not constitute an obstacle to mutual assistance.
- Regarding the breach of the chain of custody: The appellant claimed, without providing proof, that the chain of custody for a mobile phone had been broken during its analysis. The Court characterizes these allegations as "speculation" and reiterates that the assessment of the probative value of this item will be a matter for the French judge.
- Regarding the violation of proportionality: The appellant argued that the seized devices contained private data (family photos) and prohibited pornographic material, which should have been sorted and excluded from the transfer. The Court finds that the appellant failed to fulfill his duty to cooperate. Neither at first instance nor in his appeal did he precisely identify the irrelevant files or data. His objections remained purely general. He is therefore precluded from raising this grievance. Regarding the pornography, the Court notes that the Public Prosecutor's Office issued a restriction on use for the French proceedings, referring this incidental discovery to the criminal proceedings already opened in Switzerland against the appellant on this matter.
Finally, the Court rejects the request for legal aid. For the first-instance proceedings, the request was conditional and did not need to be addressed. For the appeal proceedings, the Court considers that the appeal was manifestly bound to fail, as it was limited to repeating arguments already rejected, without any new substance.
Outcome
The Appeals Chamber of the Federal Criminal Court rejects the appeal in its entirety. The decision of the Basel-Landschaft Public Prosecutor's Office authorizing the transfer of evidence to the French authorities is upheld. The request for legal aid is rejected. The court costs, set at 1,000 francs, are to be borne by the appellant.
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