The US Code &
The UN on Torture

U.S. Code collection title 18 > part I > chapter 113C > § 2340 § 2340. definitions

1. “torture” means an act committed by a person acting under the color of law specifically intended to inflict severe physical or mental pain or suffering (other than pain or suffering incidental to lawful sanctions) upon another person within his custody or physical control;
2. “severe mental pain or suffering” means the prolonged mental harm caused by or resulting from— .
   1. the intentional infliction or threatened infliction of severe physical pain or suffering;
   2. the administration or application, or threatened administration or application, of mind-altering substances or other procedures calculated to disrupt profoundly the senses or the personality;
   3. the threat of imminent death; or
   4. the threat that another person will imminently be subjected to death, severe physical pain or suffering, or the administration or application of mind-altering substances or other procedures calculated to disrupt profoundly the senses or personality; and
   5. "United States” means the several States of the United States, the District of Columbia, and the commonwealths, territories, and possessions of the United States.
      

Definition of Torture from the UN Convention against torture Part 1 Article 1

1. For the purposes of this Convention, 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.
2. This article is without prejudice to any international instrument or national legislation, which does or may contain provisions of wider application.
   
   The US Government ratified this convention on 21 Oct 1994 under
   George Bush senior.