Torture has a number of definitions under U.S. and international law, and treaties to which the United States is a signatory. In addition, all members of the United Nations, by virtue of their membership, are bound by the United Nations Charter including the United States. The United Nations Charter does not specifically ban torture but implies its prohibition in the document's Preamble. Byers argued that special, jus cogens rules, internationally accepted principles of fundamental human rights, overrule conflicting treaty provisions and include a ban on torture. The most universally accepted definition comes from the United Nations Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment. The treaty, which has not been ratified by the United States Senate, defined torture as follows:

[A]ny 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.

A number of federal laws have also codified a definition of torture. For example, United States Code, Title 18, chapter 113c, section 2340, (2004), makes it a federal crime to torture outside of the U.S. and applies to citizens of the U.S. as well as torturers “present” on U.S. soil. Section 2340 defines torture as “an act committed under the color of law specifically designed to inflict severe physical or mental pain or suffering…” The law goes on to define “severe mental or physical suffering” as prolonged mental harm caused by or resulting from…the intentional infliction or threatened infliction of severe physical pain or suffering.” The use of drugs and threats are also covered under the statute, as are “procedures calculated to disrupt profoundly the senses or personality…” According to a legal memo prepared for the White House, the law had not been applied in the context of interrogations, either military or law enforcement. Cases by which persons have challenged confessions because of the actions of police officers are usually ultimately decided based on the due process clauses of the 5th and 14th Amendments to the Constitution and the rules announced by the United States Supreme Court in Miranda v. Arizona (1966). It is noteworthy that the federal law on torture requires that the action be “specifically designed” to inflict the harm, which is not necessarily the case when questioning a suspected terrorist.

Military personnel are subject to the Uniform Code of Military Justice (2006) and, although no specific provision of the code prohibits torture, a number of sections are applicable to the use of violence during an interrogation. For example, Article 93 of the code sanctions “cruelty and maltreatment” and Article 128 punishes “assault.” Article 93 states anyone who is “guilty of cruelty toward, or oppression, or maltreatment of any person” is subject to court-martial.