The the devastating explosion at the al-Ahli Arab Hospital in central Gaza, in which the Palestinian Health Ministry says at least 500 people were killed, shows exactly why the International Criminal Court (ICC) must investigate atrocities committed in Israel and Palestine. With allegations levied from all directions, the ICC may just be the best option to provide an impartial and independent assessment of the bombing and, critically, who bears responsibility for it.

There is little doubt that the destruction of the al-Ahli Arab Hospital is a war crime, no matter who is ultimately responsible. Under the international law that governs conduct in armed conflict – International Humanitarian Law – civilians and medical professionals can never be targeted by military attacks, whether they are committed intentionally or recklessly – “when an attacker consciously disregards a substantial and unjustifiable risk of harm to civilians or civilian objects”.

Even if a warning is issued to those in a hospital or any other civilian infrastructure, patients and medics who cannot leave or who choose not to leave, still cannot be targeted. Warnings are not a magic wand that does away with the legal protections that civilians enjoy. No military advantage can be lawfully gained by bombing a hospital where civilians sought refuge, believing it was safe.

Someone is responsible. The question is who? Who is responsible for this massive loss of life, for this war crime? How are we supposed to know amid so many competing accounts and the misinformation that characterises this war?

In the immediate aftermath of the bombing, Gazan officials maintained that Israeli forces had bombed the hospital. There was some confusion as reports from sources close to Israeli authorities suggested that the Israeli military had bombed the hospital in an attack against Hamas, in an apparent admission that they had bombed it. Some observers may have been quick to assume Israeli forces were responsible because of past precedence, including reports from the World Health Organization that in the 2009 Gaza War, Israeli forces damaged more than half of the 27 hospitals and 44 medical clinics in Gaza. The Israeli military, however, denied any involvement and insisted that Islamic Jihad had misfired rockets and destroyed the hospital. Some states have backed Israel up , but many remain unconvinced

As a signatory to the Geneva Conventions, Israel is required to investigate war crimes, including any committed by its own forces. Under international humanitarian law, states have an obligation to investigate and, where necessary, prosecute anyone who has committed a war crime. The problem is that states which are themselves implicated in hostilities and alleged atrocities are rarely able or willing to impartially investigate their own.

The IDF has a history of first blaming Palestinians before, sometimes, taking responsibility for its acts of violence. A recent example is the killing of Al Jazeera journalist Shireen Abu Akleh as she was reporting on the Jenin refugee camp in the West Bank in May 2022. Israeli officials first insisted that she had been killed by Palestinian fire, only to later backtrack and apologise. It was, in fact, an Israeli sniper who had shot Abu Akleh in the head, killing her instantly. The United Nations Commission of Inquiry on the Occupied Palestinian Territory, including East Jerusalem and Israel, found that Israeli forces had used “lethal force without justification” and that Abu Akleh’s death “is a direct result of Israel’s militarisation of law enforcement operations in the West Bank, including East Jerusalem”. The targeting of journalists is a war crime. The killer has never been held accountable.

This does not mean that Israel is responsible for the loss of life at al-Ahli hospital. It just means a credible and impartial actor should be investigating, not one with a direct interest in the outcome.

Even among those states with robust and independent criminal justice systems, few have admirable records when it comes to investigating their own wartime atrocities. The fog of war and the layers of allegations are too thick. The incentive to turn a blind eye, deflect and minimise responsibility is often too strong, especially when popular support for war efforts may be at stake.

Who could possibly trust an investigation in the context of repeated calls for Gaza to be annihilated – what some might suggest is genocidal rhetoric – by the likes of Prime Minister Benjamin Netanyahu and Minister of National Security Itamar Ben-Gvir?

An international investigation is needed. The Commission of Inquiry can play a critical role and collect evidence. But it won’t itself attribute responsibility or charge those who bombed the al-Ahli Arab Hospital. As luck would have it, an investigation that could do just that already exists.

In 2021, the ICC prosecutor announced the opening of an investigation into the situation in Palestine, which covers the ongoing war in Gaza as well as any war crimes and crimes against humanity committed by Palestinian factions, including Hamas, in Israel.

Current ICC Prosecutor Karim Khan has reiterated in recent days that his office has jurisdiction over any atrocities perpetrated in Gaza. That the prosecutor has broken his silence on the situation in Israel and Gaza is good. But the ICC must act. The ICC can impartially and independently investigate international crimes in Gaza. The prosecutor should immediately announce that he is actively doing so and dedicate resources to his investigation. Israel and any actors in Gaza with effective control of the area around the hospital should immediately allow ICC investigators safe access to the site. Like they did in Ukraine, states – especially those who purport to defend human rights and international law – must support such an effort.

In denouncing war crimes and crimes against humanity in Palestine and Israel, however, many Western states and their leaders have refused to acknowledge, let alone lend their support behind the one international institution that could prosecute those very atrocities: the ICC. In Canada, for example, Prime Minister Justin Trudeau has called the situation in Gaza a “humanitarian situation”, when it is more accurate to say it is a factory of war crimes that demand justice and accountability.

Will an investigation by the ICC solve the conflict? Is criminal law the arbiter of all truths? Of course not. But it is worth trying, even if the results are not immediate. Right now, the best way through the tangle of untruths is an international investigation. The best chance of holding perpetrators to account is through the ICC.

We know for sure that inaction only breeds impunity and further violence. As international law Professor Adil Haque poignantly writes: “Investigate all of them. Hamas. The IDF. All of them. For everything. Prosecute all those responsible. All of them. Justice is not enough. But justice is all that is left.”

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.