The ICJ has been asked to consider whether Israel is committing genocide against Palestinians in Gaza.
Israel rejects the allegations as “baseless”. South Africa brought the case to the court – which is the top court of the United Nations (UN).
Ireland’s Tánaiste (deputy prime minister) and Minister for Foreign Affairs Micheál Martin announced on Wednesday that he had directed officials to commence work on a Declaration of Intervention under Article 63 of the statute of the ICJ.
Interventions by state parties under Article 63 do not take a specific side on whether genocide has been committed by Israel.
Ireland will not be asserting if genocide is being committed, but asserting its interpretation of the Genocide Convention.
This is the same approach taken by Ireland in the Ukraine v Russia case.
Work on the intervention is likely to take a number of months.
What is the ICJ?
Based in the Hague, in the Netherlands, it was established after World War Two, to settle disputes between states.
It also gives advisory opinions on legal matters, which is what it is being asked to do with Israel.
Unlike the International Criminal Court (ICC), the ICJ cannot prosecute individuals for crimes of the utmost severity, such as genocide.
But its opinions carry weight with the UN and other international institutions.
UN ceasfire resolution
Ireland is to liaise closely with a number of international partners, who have also confirmed their intention to intervene.
Belgium, Nicaragua and France have all stated their intentions to formally do so.
The case itself is set to take a number of years.
“The situation could not be more stark; half the population of Gaza face imminent famine and 100% of the population face acute food insecurity,” Mr Martin said on Wednesday.
“Ireland will be intervening.
“It is for the court to determine whether genocide is being committed.
“But I want to be clear in reiterating what I have said many times in the last few months; what we saw on 7 October in Israel, and what we are seeing in Gaza now, represents the blatant violation of international humanitarian law on a mass scale.
“It has to stop. The view of the international community is clear. Enough is enough.”
South Africa alleges Israel is committing genocide against the Palestinians, following Hamas’s 7 October attack.
Hundreds of Hamas gunmen crossed from the Gaza Strip into southern Israel, killing 1,200 people, mainly civilians, and taking about 240 hostages back to Gaza.
Since Israel launched its military campaign against Hamas in response, more than 32,400 people, mainly women and children, have been killed in Gaza, according to the Hamas-run health ministry.
The UN Security Council has adopted a resolution calling for an immediate ceasefire, as well as the release of hostages.
Israel was directed by the ICJ in January to take all additional measures to ensure that civilian lives had been protected, however sources within the Department of Foreign Affairs said the Irish government did not believe this had been done to an acceptable standard.
This is based on evidence provided by UN partners.
Israel has said it has taken a raft of measures to avoid civil casualties.
Its Prime Minister Benjamin Netanyahu said: “It is not we who have come to perpetrate genocide, it is Hamas.
“It would murder all of us if it could.
“In contrast, the IDF [Israel Defense Forces] is acting as morally as possible.”