A crime is committed when there it can be determined that both Actus Reus and Mens Rea exist – the “act” and the “intent”.

Actus Reus refers to what the defendant has done. This can be either an act (e.g. killing someone) or an omission (i.e. failing to act, for example, failing to take proper care of one’s child), which is prohibited by law. Causation has to be established as well: there should be a link between the action of the perpetrator and the consequence. For example, causation is established if it is proven that if A had not shot B, B would not have died.

Mens Rea is the mental element. There are many forms of mental responsibility, the most common being intentionally and knowingly doing something. If someone has acted intentionally, it means that the person has acted for the purpose of causing consequences, or at least while being aware that those consequences would occur. Without a confession, establishing mens rea is difficult as it entails a degree of guessing or assuming someone’s intention. However, it can be inferred and proven through looking closely at the circumstances.

In international crimes, the context in which the criminal act took place is also crucial. See for example the elements of crimes against humanity and war crimes under the Rome Statute here.

Mode of Liability in International Crimes

Since international criminal law punishes individuals responsible, the fact that a crime was committed is not enough: it must be proven that the accused individual committed the crime.

Mode of liability describes the manner in which someone is responsible for a crime. The mode of liability in international criminal law is different from domestic criminal law. The difference is needed because in international crimes, the people who are most responsible for the crime, for example political leaders, are often not the ones who actually carry out the prohibited acts (such as a massacre of civilians).

Articles 25, 28 and 33 of the Rome Statute provide examples for modes of liability. For example,

1. A person can order, solicit or induce the carrying out of a crime.

2. A person can aid, abet or assist in the carrying out of a crime.

3. A person can commit a crime as an individual or jointly with another. In the case of joint liability, an individual can be guilty of a crime by contributing to a criminal act together with a group of people. For joint liability to be decided, there must be 1) a group of individuals; 2) a common plan, design or purpose shared by the group which amounts to or involves the committing a crime; 3) the concerned individual must know about the intention of the group; 4) the individual must participate in the execution common plan, but he does not need to commit a specific crime.

4. Command responsibility is based on the idea that generally superiors are responsible for the acts of their subordinates and for failing to prevent or punish the crimes committed by their subordinates. There are three elements to this mode of liability:

i. A superior-subordinate relationship, where the superior is in effective command and control of his subordinates. This can be generally proved through military organisation charts;

ii. The superior knew or should have known that the subordinates were committing or about to commit the crime;

iii. The superior failed to take all necessary and reasonable measures to prevent or stop the commission of the crimes. For example, the superior did not discipline his subordinates or refer them for prosecution.

5. The fact that a person is just following orders of governments or superiors does not relieve that person of criminal responsibility if the orders were manifestly unlawful.


Landel Morgane. “Training Guide: International Criminal Law for Syrian Human Rights Defenders,” Euromed Rights, 2015. https://euromedrights.org/wp-content/uploads/2015/12/EuroMed-Rights-TTK-Syria-ICL-EN.pdf.

Last Updated: August 21, 2018

Author: Nova Pui Yan Tang