International Crimes
Genocide
International law criminalises certain very serious offences irrespective of domestic law. The four principal international crimes are genocide, crimes against humanity, war crimes, and aggression.
Genocide is defined in the 1948 Genocide Convention as any of the following acts committed with the intent to destroy, in whole or in part, a national, ethnic, racial, or religious group, including
- killing members of the group;
- causing serious bodily or mental harm to members;
- deliberately inflicting on the group conditions of life calculated to bring about its physical destruction in whole or in part;
- imposing measures intended to prevent births within the group;
- forcibly transferring children of the group to another group.
What distinguishes genocide from mass killing is the requirement that it is carried out with the intention to destroy, in whole or in part, the national, ethnic, racial, or religious group concerned.
Proof of intent arises from circumstances  and the overall context in which the crime occurred,
- systematic targeting of victims on account of membership of a group,
- the fact that the perpetrator may have targeted the same group during the commission of other acts,
- scale and scope of atrocities,
- frequency of destructive and discriminatory acts,
- whether the perpetrator acted based on the victim’s membership in a protected group or
- perpetration of acts that violate the very foundation of the group or considered as such by the perpetrators.
There is controversy as to whether the intention to destroy relates to physical or cultural destruction. Physical destruction is the primary test.
Questions arise regarding defining protected groups; groups must have a particular characteristic, national, ethnic, racial, or religious. Similarly, the question of who is or is not a member of a group may be difficult in particular cases.
Crimes Against Humanity
Crimes against humanity were defined in the Nuremberg statute as murder, extermination, enslavement, deportation, and other inhumane acts against civilian populations during war or persecution on political, racial, or religious grounds in execution of or in connection with any crime within the jurisdiction of the tribunal, whether or not they were violations of domestic law when perpetrated.
The most widely used definition of crimes against humanity is that in the Rome Statute for the International Criminal Court. It is defined as crimes against humanity if any of the following acts, when committed as part of a widespread or systematic attack directed against any civilian population with knowledge of the attack:
- murder, extermination,
- enslavement,
- deportation or forcible transfer of population;
- imprisonment or other severe deprivation of physical liberty in violation of fundamental rules of international law;
- torture,
- rape, sexual slavery, enforced prostitution, enforced pregnancy, enforced sterilization, any other form of sexual violence of comparable gravity;
- persecution against any identifiable group collectively or as a group on political, racial or national, ethnic, cultural, religious, gender grounds as above or other grounds that are universally recognizable as impermissible under international law;
- enforced disappearance;
- the crime of apartheid;
- other inhumane acts of a similar character intentionally causing great suffering or serious injury to the body or to mental or physical health.
Persecution may be prosecuted before the court if it is in connection with any act referred to above or any crime within the jurisdiction of the court.
Characteristics
It is the context that renders domestic crimes into international crimes for the purpose of the International Criminal Court statute. Widespread refers to the large-scale nature of the attacks and the number of victims. Systematic refers to the organised nature of the act.
An attack is a course of conduct involving the multiple commissions of acts of the type referred to in the above civilian population, pursuant to or in furtherance of a State or organisational policy to commit such attacks. The presence of non-civilians does not make a population non-civilians as long as it is predominantly so.
The mental element for the underlying crime is required. Persons committing the crime must have knowledge of the broader context that it is part of a widespread or systematic attack. In the case of persecutory crimes against humanity, the perpetrator has to intend to discriminate against those persecuted.
War Crimes
War crimes differ depending on whether the conflict is internal or international. In international armed conflicts, there are treaty-based norms; the most important of these is the Geneva Conventions.
The Statute of the International Criminal Court defines war crimes as including any of the following against persons or property protected under the provisions of the Geneva Convention, including in particular:
- wounded, sick,
- prisoners of war,
- interned civilians, and civilians in occupied territory;
- willful killing, torture or inhuman treatment including biological experiments,
- willfully causing great suffering, serious injury to body or health;
- extensive destruction or appropriation of property not justified by military necessity carried out unlawfully and wantonly;
- compelling a prisoner of war or protected person to serve in the forces of a hostile power;
- willfully depriving a prisoner of war or other protected person of the rights of a fair and regular trial;
- unlawful deportation or transfer or unlawful confinement; taking of hostages.
The ICC has jurisdiction over certain other  crimes in addition to grave breaches of the Geneva Conventions, including certain weapons offences, employing chemical weapons, declaring no quarter, sexual offences, attacking civilians, using human shields, launching an attack that will cause disproportionate collateral damage.
The ICC has a list of 12 customary war crimes for non-international armed conflicts. These include the prohibition on pillage, perfidy, sexual offences.
For conduct to constitute a war crime, it has to be connected to the armed conflict. What distinguishes a war crime from a purely domestic offence is that it is shaped by and dependent on the environment in which it was committed, namely, the armed conflict.
The armed conflict need not have been the cause of the commission of the crime, but its existence must have played a substantial part in the perpetrator’s ability to commit it, the decision to commit it, the manner in which it was committed, and the purpose for which it was committed.
In determining whether or not the act was sufficiently related to the armed conflict, the following may be taken into account:
- The fact that the perpetrator is a combatant,
- the fact the victim is a non-combatant,
- the fact the victim is a member of the opposing party,
- the fact that the act may be said to serve the ultimate goal of a military campaign
- the fact that the crime is committed as part of or in the context of the perpetrator’s official duty.
Protections of Civilians
There is provision for the prosecution of violation of Article 3 of the Geneva Convention in an international conflict. This provides that persons taking no active part in hostilities including members of armed forces who have laid down their arms, who are outside of combat because of sickness, wounds, detention, or other cause, shall in all circumstances be treated humanely, without adverse distinction based on race, color, religion, or faith, sex, birth, or any similar criteria.
For this purpose, the following acts are and remain prohibited at any time in any place whatsoever with respect to the above persons:
- violence to life or person, in particular all kinds of mutilation, cruel treatment and torture,
- taking of hostages,
- outrages against personal dignity, in particular humiliating and degrading treatment,
- passing of sentences and carrying out of execution without the previous judgment pronounced by a regularly constituted court affording all the judicial guarantees which are recognised as indispensable by civilised people.
Other ad hoc bodies have jurisdiction over violations of additional offences. These may include attacking civilians, attacking peacekeepers entitled to the protection of civilians, conscripting or enlisting children under the age of fifteen into the armed force or using them to participate actively in hostilities.
Aggression
Aggression is a controversial crime in international law. The Nuremberg statute, it criminalised planning, preparation, initiating, or waging a war of aggression or a war in violation of international treaties, agreements, or assurances or participating in a common plan or conspiracy for any of the above.
Aggression is within the jurisdiction of the International Court only if a definition is included in that statute following a review conference. Proposals have been made in relation to the definitions of aggression, including that the perpetrator planned or initiated and executed an act of aggression.
- The person was in a position to exercise control over or direct the political or military action of the State which committed the act of aggression.
- The act of aggression is the use of armed forces by the State against the sovereignty, territorial integrity, or political independence of another State or in any other manner inconsistent with the Charter of the UN was committed.
- The perpetrator was aware of the factual circumstances establishing inconsistency of the use of armed force against the Charter.
- The act of aggression by its character, gravity, and scale constituted a manifest violation of the Charter.
- The perpetrator was aware of factual circumstances establishing such a manifest violation.