The International Court of Justice (‘ICJ’), which only adjudicates disputes between states (Art. 34(1) ICJ Statute) – has unlimited ‘subject matter’ jurisdiction, i.e. ‘Jurisdiction Ratione Materiae’.

Art 36(1) states –

‘The jurisdiction of the Court comprises all cases which the parties refer to it and all matters specially provided for in the Charter of the United Nations or in treaties and conventions in force.’

So, in principle there is no limit to the subject matter of disputes which can be submitted to the court, provided that these are ‘legal disputes’ and raise issues of ‘International Law’. (Art 36(2)).

ICJ proceedings can be paused to enter into Ad Hoc Mediation, but only if both disputing states mutually request it.

The ICJ has no power to pause a case unilaterally for Mediation, nor can one state force a pause over the other’s objections.

However, if both parties agree to explore an out-of-court settlement via ‘Ad Hoc Mediation, then the Court will accommodate them.

The Court uses two primary operational mechanisms to pause a case for independent Mediation:

1. ‘The Joint Request for a Formal Suspension (Stay)’ – Historically, the ICJ almost never issued formal suspensions of proceedings. However, recent modern practice has cemented this option.

If both states agree to enter into ‘Ad Hoc Mediation’, they can submit a joint request to the Court.

In a landmark procedural shift, the ICJ issued a formal Order suspending the case in Germany v. Italy (2024).

The pause was granted explicitly because Germany requested it and Italy did not oppose it, allowing the parties time to resolve issues through external legal pathways that could eventually lead to discontinuing the ICJ case.

2. ‘Strategic Extension of Time-Limits’ – Before formal suspensions became utilized, the more common and subtle way to ‘pause’ a case was to manipulate the procedural calendar.

Under Article 44 of the Rules of Court, the ICJ has the authority to extend the time-limits for states to file their written pleadings (Memorials and Counter-Memorials).

So, if both states informed the Court that they are actively engaged in Ad Hoc Mediation and needed more time, the Court would routinely grant ‘multi-month’ extensions to their filing deadlines.

This effectively froze active litigation and created a ‘Mediation Window’ without formally halting the case.

If Ad Hoc Mediation is successful, i.e. if the states resolve their dispute out of court, then they will jointly notify the ICJ.

Under Article 88 of the Rules of Court, the parties will officially declare that they have agreed to withdraw the case.

The Court will then issue an ‘Order of Discontinuance’ and officially remove the dispute from its General List.

The ICJ also frequently exercises its authority at an early stage, such as during initial meetings between the President of the Court and the Agents of the parties, to encourage peaceful, alternative dispute resolution, including Ad Hoc Mediation or Negotiation.

During the first procedural meeting (often held immediately after a case is filed to fix time limits for memorials), the President of the Court will typically remind the parties of their obligations under the UN Charter to seek peaceful solutions.

The President routinely encourages them to consider Mediation, Negotiation, or other methods outside of formal litigation.

Because the ICJ’s contentious jurisdiction is based on state consent, the Court cannot force or order sovereign states into Mediation if they do not agree.

However, the judges strongly promote it as a preferred alternative.

Because most international cultural heritage conventions, such as the 1970 UNESCO Convention and the 1954 Hague Convention, are not retroactive, they do not apply to heritage taken during colonization, historical conquests, or other events predating the treaties. Consequently, claims for the return of cultural heritage are rarely brought in the ICJ. However this constraint does not apply to a claim based upon the illicit trade in artefacts stolen more recently, which end up on display in the public museum of a state which has submitted to the jurisdiction of the court.

States bringing claims for colonial-era or ancient historical artifacts often hit a brick wall due to the non-retroactivity of treaties like the 1954 Hague Convention and the 1970 UNESCO Convention.

However, this temporal barrier vanishes when dealing with recently illicitly traded artifacts that end up in state-owned museums.

Non-retroactivity is a cornerstone of public international law.

So, when an artefact is stolen or illicitly exported after the relevant treaties or bilateral agreements have entered into force between the states, the rule of non-retroactivity does not apply.

If a sovereign state submits to the jurisdiction of the ICJ (such as through a special agreement or a treaty containing an optional clause for dispute resolution), the Court can hear disputes regarding the illicit trafficking and unlawful possession of recent antiquities.

If a state’s public museum displays a recently stolen artifact, the claimant state can argue that the holding state is breaching its obligations to prevent illicit trade and return stolen property.