What is third-party intervention at the ICJ?

South Africa has taken Israel to the International Court of Justice (ICJ), accusing it of violating the UN's 1948 Genocide Convention in Israel's current war against Hamas in Gaza.

The Israeli military launched a massive operation against Hamas after the militant Islamist group carried out a series of terror attacks on Israel on October 7 that killed 1,200 people and saw 240 taken hostage.

Hamas is classified as a terrorist organization by the European Union, Germany, and the United States, among other nations.

Over the coming weeks, the court will have to decide whether to issue the provisional measures requested by South Africa, which include an immediate suspension of Israel's "military operations in and against Gaza." The issue of whether the genocide convention has been violated could last years.

Last Friday, Germany announced it would intervene on Israel's behalf as a third party in the case. 

How can a third party intervene?

International law expert Stefan Talmon of the University of Bonn explained that a third party could intervene because the Genocide Convention is an international treaty — it has been signed by about 150 states, including South Africa, Israel, and Germany.

"According to Article 63 of the statute of the ICJ, any party to a multilateral treaty can intervene in a dispute concerning how the treaty is interpreted," Talmon told DW. He added that a state would do this because an interpretation of the treaty by the ICJ would affect all parties.

Does a third party take sides?

In theory, Talman continued, an entity enters proceedings as a neutral party, helping the court interpret the treaty, for example. In practice, however, an entity always wants to support one of the sides with its interpretation.

He said this made sense given the nature of the proceedings: "If you have an antagonistic dispute — i.e., a dispute between two parties — and it is a question of how to interpret a treaty, then you will inevitably support one of the parties, depending on how you interpret the contract."

In its statement, the German government said that it "firmly" opposed a "political instrumentalization" of the Genocide Convention and rejected the genocide accusation leveled against Israel. "This accusation has no basis whatsoever," Berlin said.

While Israeli Prime Minister Benjamin Netanyahu thanked the German chancellor for the government's stance, Namibia has condemned Germany's support to Israel.

What role does an intervening state play?

"An intervening state presents its interpretation of the particular provisions of the treaty to the ICJ," explained Talmon, saying that this is done both in writing and orally at the hearing itself. He added that such a state could only make a statement on the treaty's provisions, not on the content of the case itself.

Talmon said it had become more common for third parties to intervene in ICJ proceedings in the past three years. Germany has intervened as a third party, alongside other states, in two other cases relating to the Genocide Convention — Ukraine v. the Russian Federation and Gambia v. Myanmar.

In South Africa's case against Israel, Bangladesh and Jordan are two states that have announced that they are prepared to intervene and present evidence supporting South Africa's case.

Talmon said he expected more than 30 declarations of intervention regarding the case, mostly on behalf of South Africa.

This article was translated from German.