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International Criminal Law

International criminal law deals with the criminal responsibility of individuals for the most serious of human rights and international humanitarian law violations. The main categories of international crimes are war crimes, crimes against humanity, genocide and the crime of aggression.

What is international criminal law?

International criminal law (ICL) is a relatively new and constantly developing branch of public international law. ICL criminalises the most serious violations of human rights and international humanitarian law (IHL), and exposes perpetrators of such conduct to criminal liability. ICL provides for criminal sanctions that apply to all perpetrators. This includes those who are involved in the planning and authorisation of such acts as well as those who directly commit the crimes. As such, those at the highest political and military levels can be held to account for international crimes.

Why is international criminal law important?

Criminal accountability for serious crimes is of fundamental importance with regard to respect for the rule of law, deterrence of future violations, and the provision of redress and justice for victims.

Are all violations of international law and international humanitarian law considered to be criminal in nature?

No, only the most serious violations of international human rights law (IHRL) and IHL are considered international crimes. Examples of international crimes include war crimes, the crime of aggression, crimes against humanity, and genocide.

International criminal law: Genocide, crimes against humanity and war crimes

International crimes are considered to affect the international community as a whole. Consequently, in addition to preventing the occurrence of these particularly heinous crimes, all states have an interest in holding the perpetrators of such crimes accountable.

Crimes such as the massacre of civilians, rape, forcible transfer, torture, indiscriminate bombings, apartheid and persecution all violate the most basic principles of humanity, morality and dignity. Over the last century, the international community has reaffirmed the importance of the protection of these basic values by prohibiting the above conduct and making individuals liable for committing such offences.


Genocide is defined as the intent to destroy, in whole or in part, a national, ethnical, racial or religious group. The acts that amount to genocide if committed in this context are:


causing serious bodily harm;

inflicting conditions of life calculated to bring about its physical destruction; imposing measures intended to prevent birth; or

forcibly transferring children of the group to another group.

The term genocide is often misused as the crime is not one which is necessarily defined by numbers or outcome, but rather by the specific intent of the perpetrators to not only harm the victims but to destroy the group as such. The crime is codified in the UN Genocide Convention, the Rome Statute of the International Criminal Court (ICC) and is examined in more detail in the jurisprudence of the International Criminal Tribunal for Rwanda. 

For more information on the crime of genocide:

Crimes against humanity 

Crimes against humanity encapsulate several acts amounting to serious human rights violations when committed as part of a widespread or systematic attack against a civilian population. Many courts, including the International Criminal Court, also require that the acts form part of a governmental or organisational policy.

Crimes against humanity include acts such as, but not limited to, torture, murder, extermination, enslavement, deportation or forcible transfer, sexual violence, persecution, and the crime of apartheid.

Crimes against humanity are codified under Article 7 of the Rome Statute of the ICC.

War crimes

War crimes are grave breaches of treaty or customary rules of IHL, and are considered to constitute the most serious violations of IHL.

They include but are not limited to willful killing, wanton destruction of private property, torture or inhuman treatment, willfully causing great suffering or serious injury to body or health, unlawful deportation or transfer, taking of hostages, recruitment and use of child soldiers, and willfully depriving a person of the rights of fair and regular trial, all occurring in the context of an armed conflict.

Unlike crimes against humanity there is no need to establish a widespread or systematic practice of massacres, as one single incident, such as recruiting one child solider or one incident of torture during an armed conflict would amount to a war crime.

Grave breaches are defined in Article 147 of the Fourth Geneva Convention (see also Article 50 in the First Geneva Convention, Article 51 in the Second Geneva Convention, Article 130 in the Third Geneva Convention and in Article 85 of the First Additional Protocol.)

For more information on war crimes:

The ICC and Article 8 of the Rome Statute that defines war crimes

The ICRC and Article 147 GCIV

The ICRC and Article 50 GCI

The ICRC and Article 51 GCII

The ICRC and Article 130 GCIII

The ICRC and Article 85 API

Individual criminal responsibility and modes of liability

Perpetrators of genocide, crimes against humanity and war crimes can be held individually criminally responsible – this in parallel with the responsibility of the state. For example, both the former Republic of Yugoslavia and certain individual political leaders and military commanders have been accused of genocide during the wars in former Yugoslavia.

Perpetrators of international crimes may be convicted on the basis of their own direct acts or omissions, or when ordering and facilitating a crime. Where international crimes form part of a broad and complex state policy, a wide range of perpetrators may be convicted under different modes of liability. The following are the most common modes of liability applied by international criminal courts and tribunals;

Committing (act or omission): Physically perpetrating a crime through an act or culpable omission. 
Indirect perpetration: Using another person to physically carry out the crime, while controlling the will of the direct perpetrator.
Joint Criminal Enterprise (JCE): Contributing, with several individuals, to criminal activity with a common purpose that is carried out either jointly or by some members of this plurality of persons. 
Co-perpetration: Being directly involved in the commission of the crime, without necessarily being a principal actor. For example, being a member of a gang that attacks an individual, without necessarily performing the physical acts constituting the assault. 
Aiding and abetting: Substantially contributing to the perpetration of the crime. 
Attempt: Taking a substantial step towards committing a crime, where independent circumstances prevent the crime from occurring.
Planning: Contemplating, planning and designing the commission of a crime, regardless of whether the crime was actually committed.
Ordering: Using a de jure or de facto authority to instruct another person to commit an offence.
Superior/command responsibility: Failure by a superior to prevent or punish the commission of a crime by a subordinate. If the superior knew, or should have known, that subordinates were going to commit a crime, but did nothing to prevent it, they can be held criminally responsible. Failure to take any action against subordinates who have already committed a crime also leads to criminal responsibility.
Conspiracy: Agreeing to commit an offence. In international law, the crime of conspiracy only exists in relation to genocide.
Incitement: Instigating, inducing, encouraging, or persuading the perpetration of the crime.

Universal jurisdiction

According to international law and the principle of universal jurisdiction, all states can prosecute a perpetrator of genocide, crimes against humanity or war crimes in their own national courts.