International criminal law is the legal branch, which deals with offences with international dimensions. It was created as a response of the serious violations of human rights and fundamental freedoms committed by the individual. In order to prevent further violations, the international community set up an international judicial mechanisms for prosecution of the perpetrators responsible for international crimes (genocide, crimes against humanity, war crimes, aggression). Only events after the Second World War finally connected the international community to abolish impunity of those responsible for serious violations of international law. In order to ensure justice, peace and suppress criminal nature of a man, international military tribunals in Nuremberg and Tokyo were set up. Atrocities in the former Yugoslavia and Rwanda in the early nineties encouraged the UN Security Council to set up an ad hoc judicial bodies with jurisdiction over the said area. The Rome Statute established a permanent International Criminal Court, which in 2002 began to implement a complementary jurisdiction over the Contracting States.
Compared to the offences established in national criminal law, international crimes are more complex and broader in the sense of seeking accountability of perpetrators of international crimes. For this discussion it is necessary to know the details of the relationships between the participants of international crimes in order that the court can properly and legally define participation of the individual in the concrete unlawful conduct. International criminal courts have due to this reason through case law developed new legal institutions. In accordance with them it is possible to cover all the perpetrators responsible for international crimes.
Due to the abundance of potential perpetrators and participants of international crimes it is extremely important where or how to determine the individuals liable for the infringement of international law. The chain of responsible individuals for certain international crime starts with the direct perpetrators on the ground and ends with leaders of concrete unlawful act. The latter have often a detailed plan on the basis of which they carry out international crimes. Subordinates exercise amoral objective set out in this plan and obey superiors' commands.
For determining the criminal responsibility of individual it is extremely important to know the relationships and duties that are assigned to an individual in a hierarchical formed criminal system. The court must carefully investigate the facts, which is due to the already mentioned abundance of the perpetrators, victims and witnesses extremely difficult. Notwithstanding the issue of prosecution and trial for international crimes, the court must be satisfied beyond reasonable doubt that the alleged offender is guilty of the international crimes. Despite the legitimate objective of the international community, which is a mandatory punishment of individuals responsible for international crimes, the established principles of criminal law vary due to the nature of international crimes. Certain institutes in international criminal law are modified in a way that effectively reaches the conviction of responsible individuals.