Is Vladimir Putin a war criminal, and who decides?

Joe Biden called Vladimir Putin a “war criminal” on Wednesday for the unfolding onslaught in Ukraine, where hospitals and maternity wards have been bombed.

But declaring someone a war criminal is not as simple as just saying the words. There are set definitions and processes for determining who is a war criminal and how they should be punished.

Here’s a look at how this all works:

Who is a war criminal?

The term applies to anyone who violates a set of rules adopted by world leaders known as the law of armed conflict. The rules govern how countries behave in times of war.

Those rules have been modified and expanded over the past century, drawn from the Geneva conventions in the aftermath of the second world war and protocols added later.

The rules aim to protect people not taking part in fighting and those who can no longer fight, including civilians such as doctors and nurses, wounded troops and prisoners of war. Treaties and protocols lay out who can be targeted and with what weapons. Certain weapons are prohibited, including chemical or biological agents.

What specific crimes make someone a war criminal?

The “grave breaches” of the conventions that amount to war crimes include wilful killing and extensive destruction and appropriation of property not justified by military necessity. Other war crimes include deliberately targeting civilians, using disproportionate force, using human shields and taking hostages.

The international criminal court (ICC) also prosecutes crimes against humanity committed in the context of “a widespread or systematic attack directed against any civilian population”. These include murder, extermination, forcible transfer, torture, rape and sexual slavery.

The most likely way that Putin could come to be defined as a war criminal is through the widely recognised legal doctrine of command responsibility. If commanders order or know or are in a position to know about crimes and did nothing to prevent them, they can be held legally responsible.

What are the paths to justice?

Generally, there are four paths to investigate and determine war crimes, though each one has limits. One is through the ICC.

A second option would be if the UN turns its work on the inquiry commission over to a hybrid international war crimes tribunal to prosecute Putin.

A third would be to create a tribunal or court to try Putin by a group of interested or concerned states and groups, such as Nato, the EU and the US. The military tribunals at Nuremberg against Nazi leaders are an example.

Finally, some countries have their own laws for prosecuting war crimes. Germany, for example, is already investigating Putin. The US does not have such a law, but the justice department has a section that focuses on acts including international genocide, torture, recruitment of child soldiers and female genital mutilation.

Where might Putin be put on trial?

It is not clear. Russia does not recognise the jurisdiction of the ICC and would not send any suspects to the court’s headquarters in The Hague, Netherlands. The US does not recognise the authority of the court either. Putin could be tried in a country chosen by the UN or by a consortium of concerned countries. But getting him there would be difficult.

Have national leaders been prosecuted in the past?

Yes. From the tribunals in Nuremberg and Tokyo to more recent ad hoc hearings, senior leaders have been prosecuted for their actions in countries including Bosnia, Cambodia and Rwanda.

The former Yugoslav leader Slobodan Milošević was put on trial by a UN tribunal in The Hague for fomenting bloody conflicts as Yugoslavia crumbled in the early 1990s. He died in his cell before the court could reach a verdict. His Bosnian Serb ally Radovan Karadžić and the Bosnian Serb military leader, Gen Ratko Mladić, were successfully prosecuted and are serving life sentences.

The former Liberian president Charles Taylor was sentenced to 50 years after being convicted of sponsoring atrocities in neighbouring Sierra Leone. Chad’s former dictator Hissène Habré, who died last year, was the first former head of state to be convicted of crimes against humanity by an African court. He was sentenced to life.