The mandate of the Tribunal is to bring to justice those responsible for serious violations of international humanitarian law committed in the former Yugoslavia since 1991 and thus contribute to the restoration and maintenance of peace in the region.

In accordance with its Statute, the ICTY has jurisdiction over the territory of the former Yugoslavia from 1991 onwards. It has jurisdiction over individual persons and not organisations, political parties, army units, administrative entities or other legal subjects.

Although the ICTY and national courts have concurrent jurisdiction over serious violations of international humanitarian law committed in the former Yugoslavia, the ICTY can claim primacy and may take over national investigations and proceedings at any stage if this proves to be in the interest of international justice. It can also refer its cases to competent national authorities in the former Yugoslavia.

The Tribunal has authority to prosecute and try individuals on four categories of offences: grave breaches of the 1949 Geneva conventions, violations of the laws or customs of war, genocide and crimes against humanity. The ICTY has no authority to prosecute states for aggression or crimes against peace; these crimes are within the jurisdiction of The International Court of Justice.