The presented study analyses the topic of universal jurisdiction, the concept of which is an controversial issue. Being a notion of national law, it has attractted much attention at the international level as well.The article points out the theoretical basis of the jurisdiction, followed by inquiry of the meaningful linking between universal jurisdiction and hypothetical cases to prosecute. The article also analyses the difference between so-called mandatory and permissive universal jurisdiction, explaining the relation between international treaty and international custom. Moreover, apart from examples of national legislative, jurisdiction of international criminal tribunals in the relation to universal jurisdiction is addressed as well. The universal jurisdiction itself is not generally accepted, the opinions about it are not unified. Indeed, there are many bars to its application. However, although it could be a bad master, it could also be a good servant.