In its judgment of June 17, 2025 (No. 24-87.110), the Criminal Chamber of the Court of Cassation (Chambre criminelle de la Cour de cassation) ruled that a measure involving the infiltration of mobile devices to extract communication, traffic, and location data constitutes, under European Union law, an "interception of telecommunications" within the meaning of Article 31(1) of Directive 2014/41/EU. Consequently, when such a measure is executed on the territory of another Member State, it must be notified to the authorities of that State, in accordance with CJEU case law (CJEU, April 30, 2024, C-670/22, EncroChat).
By reaffirming the necessity to comply with judicial cooperation mechanisms (Article 31 notification within the EU, mutual legal assistance for third countries) even when the evidence is intangible and easily "relocatable," the ruling places strict boundaries on cross-border digital investigations and provides significant leverage for the defense in cases based on the infiltration of encrypted phones (EncroChat, SkyECC, etc.).