In the thirteenth century, the Roman lawyer, Azo, gave his definition: 'Torture is the inquiry after truth by means of torment'. However, the persistence of torture in the world and the impossibility so far of eradicating it make it important to recognize the necessity of narrowing a definition in order to gain a deep insight into the phenomenon. The prohibition of torture is absolutely and fundamentally embedded within international law. Comparing conceptions of torture in international human rights law and international criminal law, both in doctrine and case law, Sir Nigel Rodley detects three props as central in our modern legal understanding of the concept of torture: the intensity of pain or suffering inflicted; the status of the perpetrator; the question of purpose. The public character of torture is also evident in its use by non-state social actors. Incontestably, torture deals with physical and psychological torment and is accurate at targeting vital human needs.