On 19 September, the Committee of Ministers of the Council of Europe adopted the Third Additional Protocol to the 1959 European Convention on Mutual Assistance in Criminal Matters, open for signature by Member States, which aims to strengthen the capacity to respond to crime, particularly cybercrime, by updating judicial cooperation mechanisms. The Protocol introduces measures to broaden and accelerate requests for assistance, prioritise electronic communications with security guarantees, make it more flexible to hold hearings via videoconference, allow the use of technological recording devices in the territory of other States under rules of notification and authorisation, and establish specific procedures for the interception of telecommunications, balancing effectiveness in combating transnational crime with the safeguarding of national sovereignty, fundamental rights and legal certainty.
On 19 September, the Committee of Ministers of the Council of Europe adopted the text of the Third Additional Protocol (Protocol) to the 1959 European Convention on Mutual Assistance in Criminal Matters (Convention), which is open for signature by Member States.1
This Legal Alert seeks to highlight the most significant developments in this instrument of judicial cooperation in criminal matters.
I. Objective
The Protocol, which updates the Convention and its two previous Additional Protocols, aims to strengthen the capacity and effectiveness of States in responding to crime by adopting rules aimed at modernising and adapting existing mutual assistance mechanisms to new forms of crime, with an emphasis on cybercrime.
II. Measures
The Protocol includes a set of measures aimed at:
- extending the scope of requests for assistance;
- simplifying and accelerating assistance procedures;
- expanding the use of electronic communication channels and videoconferencing;
- permitting the use of technical surveillance tools; and
- setting deadlines for responses.2
A) Preference for electronic communication channels
The Protocol established electronic communications as the preferred means for mutual assistance requests and other communications under the Convention.
To this end, States Parties are required to take the necessary measures to ensure the security and authenticity of communications, in particular through electronic signatures.
B) Hearing by videoconference
Under the Second Protocol to the Convention, the hearing of persons as witnesses or experts by videoconference could only be requested when the requesting State Party considered it impossible or undesirable for that person to appear in its territory.
With the aim of providing greater flexibility, the Protocol now allows a State Party to request another State Party to inquire witnesses or experts located in its territory via videoconferencing, whenever it deems appropriate, provided that a judicial authority of the requested State Party is present.
C) Use of technological recording devices in the territory of another State
The Protocol establishes a framework for cooperation on the use of technological recording devices (sound, images or locations) authorised by the judicial authority of one State Party in the territory of another, seeking to reconcile operational effectiveness in combating serious transnational crime with the safeguarding of national sovereignty, fundamental rights and legal certainty.
Under the Protocol, a State Party using recording devices may, as a rule, continue to use them in the territory of another State Party, unless the latter decides otherwise.
Where possible, the State wishing to use such means must first submit a request for mutual assistance, duly substantiated in both factual and legal terms.
The Protocol also provides for an accelerated notification procedure for urgent situations where it is not feasible to submit a prior request for mutual assistance. In such cases, the State Party in whose territory the recordings are to be made shall be notified as soon as possible, and the requested State Party shall respond within a maximum period of 96 hours.
If the requested State Party validates the use of the device, the activity already carried out is considered to be regularised and the recordings may continue. Otherwise, the use must cease and additional conditions may be imposed, namely a total or partial prohibition on the use of the material collected on its territory.
A State Party may refuse the use of such devices if, in a comparable situation, it would not be authorised domestically or in any other circumstances that would justify a refusal of mutual assistance.
In the absence of express authorisation from the requested State Party, the recordings may not be used as evidence in criminal proceedings by the requesting State.
D) Interception of telecommunications
The Protocol establishes a specific procedure for cooperation in the interception of telecommunications, requiring that the factual and legal grounds necessary for the requested State Party to assess the admissibility of the measure in the light of its domestic law be forwarded to it.
The requested State Party may refuse the request or accept it subject to certain conditions, if it considers that, under its domestic law, the measure is not admissible as requested.
The judicial authorities of the requested State Party may also, after consulting the requesting State, destroy irrelevant or confidential material before transmitting the records.
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1 Portugal signed the Protocol on 19 September 2025.
2 Requests for mutual assistance shall be treated with the same priority as domestic cases. If the requesting State Party indicates urgency (e.g., defendants in custody), the requested Party shall endeavour to meet the deadline set. If this is not possible, the requested State Party shall immediately inform the requesting State Party, and a new timetable and conditions for execution may be agreed upon.
