War crimes are those violations of international humanitarian law (treaty or customary law) that incur individual criminal responsibility under international law. As a result, and in contrast to the crimes of genocide and crimes against humanity, war crimes must always take place in the context of an armed conflict, either international or non-international.
What constitutes a war crime may differ, depending on whether an armed conflict is international or non-international. For example, Article 8 of the Rome Statute categorises war crimes as follows:
Grave breaches of the 1949 Geneva Conventions, related to international armed conflict;
Other serious violations of the laws and customs applicable in international armed conflict;
Serious violations of Article 3 common to the four 1949 Geneva Conventions, related to armed conflict not of an international character;
Other serious violations of the laws and customs applicable in armed conflict not of an international character.
From a more substantive perspective, war crimes could be divided into: a) war crimes against persons requiring particular protection; b) war crimes against those providing humanitarian assistance and peacekeeping operations; c) war crimes against property and other rights; d) prohibited methods of warfare; and e) prohibited means of warfare.
Some examples of prohibited acts include: murder; mutilation, cruel treatment and torture; taking of hostages; intentionally directing attacks against the civilian population; intentionally directing attacks against buildings dedicated to religion, education, art, science or charitable purposes, historical monuments or hospitals; pillaging; rape, sexual slavery, forced pregnancy or any other form of sexual violence; conscripting or enlisting children under the age of 15 years into armed forces or groups or using them to participate actively in hostilities.
War crimes contain two main elements:
A contextual element: “the conduct took place in the context of and was associated with an international/non-international armed conflict”;
A mental element: intent and knowledge both with regards to the individual act and the contextual element.
In contrast to genocide and crimes against humanity, war crimes can be committed against a diversity of victims, either combatants or non-combatants, depending on the type of crime. In international armed conflicts, victims include wounded and sick members of armed forces in the field and at sea, prisoners of war