https://ijrcenter.org/cases-before-national-courts/domestic-exercise-of-universal-jurisdiction/
Extract
The term “universal jurisdiction” refers to the idea that a national court may prosecute individuals for serious crimes against international law — such as crimes against humanity, war crimes, genocide, and torture — based on the principle that such crimes harm the international community or international order itself, which individual States may act to protect. Generally, universal jurisdiction is invoked when other, traditional bases of criminal jurisdiction are not available, for example: the defendant is not a national of the State, the defendant did not commit a crime in that State’s territory or against its nationals, or the State’s own national interests are not adversely affected.
National courts can exercise universal jurisdiction when the State has adopted legislation recognizing the relevant crimes and authorizing their prosecution. Sometimes this national legislation is mandated by international agreements, such as the Convention Against Torture and Inter-American Convention to Prevent and Punish Torture, which require States parties to adopt the laws necessary to prosecute or extradite any person accused of torture who is within the State party’s territorial jurisdiction.
The definition and exercise of universal jurisdiction vary around the world. A national or international court’s authority to prosecute individuals for international crimes committed in other territories depends on both the domestic legal framework and the facts of each particular case.
