A third party intervention is the term given to the process by which any person other than the applicant, or another State Party to the European Convention on Human Rights other than that against which the application has been lodged, to intervene in the proceedings. The person or State in question is entitled to file pleadings and take part in public hearings.

The objective of a third party intervention before the European Court of Human Rights is to provide the court with information to assist it in reaching its decision; as such it is also known as amicus curiae, or “friend of the court”. A third party intervention should endeavor to objectively present law and practices relevant to the case. Third party interventions are usually made concerning cases which carry the potential of having a broad impact beyond the direct parties involved in an effort to ensure the development of good precedents and jurisprudence.  Most often third party interventions before the European Court of Human Rights are brought by NGOs or academic centers to bring to light the latest standards of international human rights law and comparative jurisprudence and practices.

Under changes introduced through Protocol No. 14 to the Convention, the Council of Europe Commissioner for Human Rights may submit written comments to the Court and take part in hearings in any case before the Chamber of Grand Chamber (Article 36(3); Rule 44(2)).

The European Court operates a well-established and important system for intervention in cases by third parties. The Court may permit Convention states to intervene under Article 36 of the Convention and Rule 44.

Thus, under Article 36 (1) of the Convention, a state is entitled to intervene to submit written comments and/or take part in hearings where the applicant is one of its nationals[1].  Furthermore, Article 36 also permits ‘any person concerned’ (which might include a state, or an individual, or an organization) to intervene if it is considered to be ‘in the interest of proper administration of justice’. Any time after the Court has given the respondent state notice of the application, a third party may be given permission by the Court to submit written comments or, in exceptional cases, to take part in hearings (Article 36(2); Rule 44(3))[2].

Any third party seeking to intervene should write to the President of the Chamber for permission to do so within 12 weeks.[3]  The request for leave must be ‘duly reasoned’. If the request is granted, the Court will almost invariably set out certain conditions for intervening. These conditions are likely to include a maximum length for the written submissions (commonly 10 to 15 pages), a specified time limit for lodging the submissions and, importantly, conditions as to the matters which can be covered by the intervention. It is usual for the Court to indicate that the intervention should not comment on the particular facts or merits of the case (as those are matters for the parties).

Requests for permission to lodge third party interventions will usually be made in relation to the merits stage of the proceedings. It is also possible to be granted permission to lodge a third party intervention for the purposes of deciding admissibility (see, e.g. TI v. UK, application no. 43844/98, decision 7 March 2000).