Cour de cassation: the absence of a right of appeal in France does not pose a constitutional problem - Implications for SkyECC and EncroChat cases

Cour de Cassation in Paris

On 3 June 2025, the Cour de cassation refused to refer to the Conseil constitutionnel a question on the constitutionality of French law which, as currently drafted, denies the possibility of an effective remedy to persons prosecuted in criminal proceedings abroad, but on the basis of SkyECC evidence gathered in French proceedings.

Genesis of the procedure

This question on the constitutionality of French law arises in the context of an action brought before the French courts by a Belgian national. Our client is being prosecuted in criminal proceedings before the Bruges court for drug trafficking and criminal conspiracy. The charges are based primarily on transcripts of messages exchanged via the SkyECC messaging system, which he is suspected of having used.

These messages are part of the one billion SkyECC data items that were captured in the context of a French case being investigated in Paris. Once collected, these messages were analysed, transcribed and then forwarded to the Belgian judicial authorities, who opened dozens of SkyECC files, including the file in which our client is implicated.

As the data on the SkyECC servers and telephones was captured in France, in the context of French criminal proceedings, under French law, the Belgian courts logically considered themselves incompetent to rule on the legality of this capture.

This Belgian national defence team, consisting in particular of Justus Reisinger and Guillaume Martine, founders of the Joint Defense Team, then devised a transnational strategy consisting in bringing an action before the French courts to invalidate the investigations into SkyECC, even though he was not being prosecuted in France. This application was filed in October 2024.

Guillaume Martine

Justus Reisinger

The problems posed by the French legal framework

Articles 170 and 173 of the French Code of Criminal Procedure set out the list of persons who may apply to the Court of Appeal to challenge the legality of investigative acts carried out in the context of French criminal proceedings. Thus, all parties to the proceedings may submit such a petition to the court: the investigating judge, the public prosecutor, the victim, the assisted witness and the defendant. However, there is an important caveat: these can only be parties to French criminal proceedings. Conversely, a person who has been implicated in criminal proceedings abroad is not entitled to challenge an investigation carried out in France, even if the evidence collected is subsequently used in the proceedings against him in his own country.

There is one exception to this exclusion, set out in article 694-41 of the Code of Criminal Procedure: when an investigative act is carried out in France, but in execution of a European Investigation Order (EIO) issued by another State in the context of criminal proceedings, the person implicated in these proceedings may appeal to the Court of Appeal to challenge the legality of this investigative act.

However, in the case involving our client, as in all the EncroChat and SkyECC cases in Europe, France did not collect the evidence in execution of an EIO issued by Belgium, but on its own initiative in the context of French criminal proceedings, even though there was police cooperation with Belgium and the Netherlands in the context of a joint investigation team (JIT). It was only once the SkyECC data had been collected by the French investigators that they were transmitted to Belgium. Our client is therefore unable to lodge an appeal under article 694-41 of the Code of Criminal Procedure.

Priority question on constitutionality

In November 2024, the Paris Court of Appeal rejected our application, declaring it inadmissible, which is a logical application of French law. An appeal was then lodged with the Cour de cassation. It was in this context that the defence asked the Cour de cassation to refer a "question prioritaire de constitutionnalité" (QPC) to the Conseil constitutionnel, concerning articles 170 and 173 of the Code of Criminal Procedure.

It is clear that the impossibility for a person implicated in criminal proceedings abroad to challenge the legality of evidence previously collected in France contravenes the constitutional right to an effective remedy, a fair trial and the rights of the defence.

On 3 June 2025, the Cour de cassation refused to refer this priority question of constitutionality to the Conseil constitutionnel, preventing it from being able to rule on this major issue. The Court of Cassation considered that the principle of limiting the right to lodge an application for a declaration of nullity met the need to protect the secrecy of the investigation and the presumption of innocence (§6 and 7). In addition, the Cour de cassation considered that the breach of the right to an effective remedy and the right to a fair trial, which would result from the impossibility of lodging an application for a declaration of nullity in France, did not ultimately concern a French court but a foreign proceeding (§8). In these circumstances, the complaints raised by our client are "inoperative", and the Cour de cassation considers that there is no reason to refer this question to the Conseil constitutionnel.

This argument is extremely open to criticism. By filing an application for a declaration of nullity before the French court, this Belgian national initiated French legal proceedings, to which constitutional principles must be able to be applied. The Court of Cassation's refusal to refer this question validates a legal system that creates inequality between people charged in criminal proceedings on the basis of evidence gathered in France, depending on whether the criminal proceedings are initiated in France or abroad.

Furthermore, the position expressed by the Cour de Cassation confirms that the assertions made by the French Government before the ECtHR in the case of AL and EJ v France, in which the Court handed down its decision on 24 September 2024 (n° 44715/20 and 47930/21), are incorrect. In this case, two British nationals were being prosecuted in criminal proceedings in the United Kingdom on the basis of evidence derived from the EncroChat data capture (similar to that relating to SkyECC) initially carried out in the context of French criminal proceedings. The French Government argued that these nationals could have applied to the French court for a declaration of nullity, but had not done so. The Court then held that they had not exhausted all remedies. However, when such appeals are lodged with the French court, the latter declares them inadmissible, as this case clearly illustrates.

Cour de Cassation in Paris

Outlook

The Court of Cassation still has to rule on the merits of the appeal lodged by our client, as well as numerous other appeals that we have lodged on behalf of Dutch, German, Italian, Norwegian nationals... The Court will also have to rule on the preliminary questions that we have suggested it refer to the CJEU. Further developments are expected in September 2025.

If the Cour de cassation were to rule definitively that a person implicated in proceedings abroad on the basis of evidence gathered in French proceedings cannot challenge the legality of that evidence before the French court, then this situation would have to be referred to the ECtHR for assessment. Furthermore, for each person who has tried unsuccessfully to bring a case before the French court, the national judge will be called upon to draw all the consequences of this impossibility of being able to challenge the legality of what is, more often than not, the central piece of evidence in the Encrochat or SkyECC cases.

You will find the decision of the cour de cassation here.