Belgium has formally joined the landmark genocide case brought by South Africa against Israel at the International Court of Justice (ICJ), deepening a widening international legal challenge to Israel’s conduct in Gaza and further isolating it within the world’s highest judicial forum.
In a filing lodged on 23 December, Belgium submitted a declaration of intervention under Article 63 of the ICJ Statute — a provision that allows any state party to a treaty under dispute to participate when that treaty’s interpretation is at stake. Because the case centers on the 1948 Genocide Convention, Belgium, like dozens of other signatories, is legally entitled to intervene.
Belgium’s move places it alongside a growing group of countries that have already entered the proceedings, including Brazil, Colombia, Ireland, Mexico, Spain, and Türkiye, marking one of the largest multilateral engagements in a genocide case in the court’s history.
While South Africa remains the sole applicant state accusing Israel of violating the Genocide Convention, intervening states play a powerful role: they shape how the court interprets the law itself — including the meaning of genocide, the standard of proof, and the obligations of states to prevent mass atrocity.
What Belgium Is Arguing
Belgium’s filing focuses on the core articles of the Genocide Convention, with particular emphasis on Article II, which defines genocide and its requirement of “specific intent” — the legal threshold for proving that acts such as killing, mass displacement, or deprivation of basic necessities were carried out with the purpose of destroying a protected group in whole or in part.
By intervening, Belgium is not introducing new evidence about Gaza but is instead attempting to influence how the court interprets what constitutes genocidal intent in situations of prolonged, high-intensity warfare against a civilian population.
This distinction matters. In genocide law, intent is often the hardest element to prove. How the ICJ interprets intent in the Gaza case will shape not only this ruling but also future international cases involving mass civilian harm.
The court has now invited both South Africa and Israel to submit written observations responding to Belgium’s intervention before deciding how its legal arguments will be incorporated into the proceedings.
A Case That Has Become Global
South Africa filed its case against Israel in December 2023, alleging that Israel’s military campaign in Gaza — marked by mass killing, widespread destruction, forced displacement, and the obstruction of humanitarian aid — violated Israel’s obligations under the Genocide Convention.
In early 2024, the ICJ issued a series of provisional measures, ordering Israel to take steps to prevent acts that could fall under the Convention and to allow humanitarian assistance to reach Gaza’s civilian population. While the court cannot enforce its orders directly, they are legally binding and carry significant diplomatic and legal weight.
Since then, the case has evolved into something larger than a bilateral dispute. With countries from Europe, Latin America, the Middle East, and Africa intervening, the Gaza proceedings are becoming a global legal referendum on how genocide law applies to modern warfare.
Israel Pushes Back
Israel has rejected the genocide allegations, calling the case politically motivated and legally flawed. It argues that its military operations are directed at Hamas and conducted in self-defence, and that civilian harm, while tragic, does not meet the threshold for genocide.
But the expanding circle of intervening states tells a different story: one of mounting international concern that Gaza has crossed into territory where mass atrocity law must apply.
Belgium’s intervention, coming from a core European Union state with deep ties to international legal institutions, further underscores the shift. This is no longer a case driven solely by states in the Global South — it now spans continents and political alignments.
Why It Matters
Interventions under Article 63 are rare in ordinary cases. Here, they are becoming routine.
That reflects the extraordinary stakes: the ICJ is being asked to define how genocide law applies to one of the most heavily documented civilian catastrophes of the 21st century. Every new state that intervenes increases the legal pressure on the court to produce a ruling that cannot be dismissed as marginal or partisan.
Belgium’s entry adds weight to that pressure — and further erodes Israel’s claim that the case represents a fringe diplomatic attack rather than a central test of international law itself.
As the Gaza case moves slowly through the court’s merits phase, what is unfolding is not only a legal battle over Israel’s conduct, but a broader struggle over whether the post-1945 promise of “never again” still carries force in a world of strategic alliances, vetoes, and unrestrained military power.