They will also be supported by Slovenia.
This comes only weeks after the ICJ heard oral observations by South Africa and Israel in the ICJ genocide hearing against Israel.
South Africa accused Israel of breaking the Genocide Convention and intending to destroy a substantial part of the Palestinian population.
What is the case brought forward by Indonesia and Slovenia?
Indonesia and Slovenia said they will both be joining proceedings that seek an advisory opinion on Israel's control of, and policies, on the occupied Palestinian territory.
Slovenia threw its weight behind South Africa’s case and said it would take part in the hearing due to take place in February.
The ICJ, also known as the World Court, is scheduled to conduct public hearings on February 19 at The Hague, where parties will present their perspectives on the legal consequences of Israel's occupation of Palestinian territories.
Authorities at Slovenia’s capital, Ljubljana said that Israel's war on Gaza and increased Israeli violence in the occupied West Bank were the reasons for its decision to take part in the action.
"This is a very broad spectrum of alleged violations that have been committed in the region for decades and whose horrific consequences are still visible today," Slovenian Foreign Minister Tanja Fajon said at a press conference.
"In the light of recent events in Gaza and the West Bank, Slovenia, as one of the few EU countries, has decided to actively participate and present its views in these proceedings before the International Court of Justice, which has been asked to give an advisory opinion."
Foreign Minister of Indonesia, Retno Marsudi emphasised the importance of upholding international law, asserting that Israel's occupation, persisting for over 70 years, cannot erase the Palestinian people's right to independence.
Speaking ahead of discussions with international law experts in Jakarta, Marsudi said: "Our deliberations will not only support Indonesia’s diplomacy, but also support the enforcement of world order according to international law and our Palestinian brothers and sisters to achieve their independence.
“International law must be upheld. The right of the Palestinian people to self-determination must be respected. Israel's occupation of Palestine, which has lasted for more than 70 years, will not erase the right of the Palestinian people to independence.”
The UN General Assembly, adopting a resolution in December 2022, requested the ICJ to provide a non-binding advisory opinion on the matter.
What was South Africa’s case against Israel?
On January 11 and 12, South Africa accused Israel of breaching the UN Genocide Convention, saying that even the deadly October 7 Hamas attack could not justify such alleged actions, as it opened a case at the top UN court.
South Africa requested several measures. The provisional measures South Africa has requested include having Israel "immediately suspend" its Gaza offensive, stop forced displacement of Palestinians in the territory and enable humanitarian access, and preserve evidence.
The decisions of the ICJ are binding upon countries, and cannot be appealed. However, it is worth noting that the ICJ has no way of enforcing its rulings and they are sometimes completely ignored.
But what are the differences between South Africa’s case against Israel and the cases brought forward by Indonesia and Slovenia?
The main difference between the cases is the difference in opinion.
Indonesian law expert Hikmahanto Juwana said the ICJ decision in this case is only advisory, contrary to South Africa’s legal case heard last week.
“The advisory opinion is not the same as an ICJ court decision. Advisory opinion only has a quote unquote moral binding,” Juwana told RT News.
The ICJ hearing in February is distinct from the case initiated by South Africa accusing Israel of "genocidal acts" in Gaza.
It is also worth noting that Indonesia has not joined the latter case, as it is not a party to the Genocide Convention. However, Indonesia supports South Africa's efforts to report Israel's violations of the Genocide Convention to the ICJ.