Torture, as understood in international law, involves several elements: the infliction of severe pain (whether physical or psychological) by a perpetrator who acts purposefully and on behalf of the state. The United Nations Convention against Torture defines torture this way:
For the purposes of [the] Convention, the term “torture” means any act by which severe pain or suffering, whether physical or mental, is intentionally inflicted on a person for such purposes as obtaining from him or a third person information or a confession, punishing him for an act he or a third person has committed or is suspected of having committed, or intimidating or coercing him or a third person, or for any reason based on discrimination of any kind, when such pain or suffering is inflicted by or at the instigation of or with the consent or acquiescence of a public official or other person acting in an official capacity. It does not include pain or suffering arising only from, inherent in or incidental to lawful sanctions.
— [Article 1.]