Note for information on the participation of non-member States in Council of Europe treaties

Participation in most Council of Europe treaties is not exclusively limited to the member States of the Council of Europe. The treaties concerned are "open" ones, open to accession by non-member States, even non-European States, provided that they have been formally invited to accede by the Committee of Ministers of the Council of Europe.

The modalities of accession by non-member States are set up in the final clauses of each treaty. However, in a general manner, for a non-member State to be invited to accede to a Council of Europe treaty, the unanimous agreement of the Parties is required.

A note for information on the specific modalities of accession to the treaties “open” to non-member States is available on the information page of each relevant treaty, on the Treaty Office website.

The procedure for the accession of a State which is not a member of the Council of Europe can be summarised as follows:

1. In principle, the Committee of Ministers may take the initiative of inviting a non-member State to accede to a specific Convention. It is nevertheless customary for the non-member State to request accession in a letter addressed to the Secretary General of the Council of Europe. The letter should be signed by the Minister for Foreign Affairs or a diplomatic representative acting upon instructions of his/her government.

2. In accordance with the Council of Europe's practice and before formally inscribing the point on the agenda of the Committee of Ministers, the Secretariat consults the member States' delegations, and the other non-member States which are Parties to the Convention, on the request for accession.

3. Formal requests for accession are examined by a Rapporteur group of the Committee of Ministers and, then, by the Committee of Ministers. The decision inviting the non-member State is usually taken at the level of the Ministers' Deputies.

Even if the treaty is silent on the matter, the Committee of Ministers may request that an expertise be carried out, concerning the compatibility of the domestic law of the State concerned with the standards of the Council of Europe. Such consultation takes place particularly if the subject of the Convention renders it advisable and if at least one member State so requests during the deliberations of the Committee of Ministers. It is likely that consultation of a committee of experts will considerably prolong the procedure, which may easily last more than a year. When there is no consultation, the necessary decisions may be taken in a much shorter time.

4. It must be noted that the Committee of Ministers decided, in April 2013, to limit the validity of invitations of non-member States to accede to conventions to a period of five years.

5. An invitation to accede to one of the Council of Europe Conventions is notified to the State concerned, which, prior to acceding, has to take the necessary measures to ensure that its domestic law allows the Convention to be implemented. It should be noted in this context that within the Council of Europe, there are various committees of experts to monitor the application of treaties by States Parties. For example, the Council of Europe has a committee of experts which monitors the application of the conventions in the penal field (PC-OC). For more information: PC-OC website.

6. It is customary for the instrument of accession to be deposited at the seat of the Council of Europe in Strasbourg, in the presence of a representative of the acceding State and of the Secretary General of the Council of Europe or his/her deputy. The representative of the acceding State brings with him/her the instrument of accession, and a procès-verbal of deposit is signed by both Parties. Should it prove difficult for the acceding State to send a representative to Strasbourg, the instrument of accession may be sent by diplomatic courier. Deposit of the instrument of accession is notified to the members of the Council of Europe and to the other Parties to the Convention. States having acceded to a Convention are entitled to accede to the Protocols thereto.

7. Subject to the applicable provisions of each treaty and in line with the Vienna Convention on the Law of Treaties, any declarations or reservations are to be made when depositing the instrument of accession. For reasons of legal certainty and in order to ensure the uniform implementation of Council of Europe Conventions, reservations may not be made at any later date.

8. Lastly, it should be noted that certain Council of Europe conventions contain a provision on the financing of their follow-up mechanism by non-member States. The Committee of Ministers has adopted, on 1 July 2020, Resolution CM/Res(2020)6 concerning financial arrangements for the participation of non-member States in Council of Europe conventions, which replaces the Resolution CM/Res(2015)1 adopted on 18 February 2015.