There are two international conventions that handle cruel treatment. In countries that have signed and ratified these conventions, they are directly enforcable law.
Article 7
No one shall be subjected to torture or to cruel, inhuman or degrading treatment or punishment...
Article 10
- All persons deprived of their liberty shall be treated with humanity and with respect for the inherent dignity of the human person.
The Covenant has 173 parties and six more signatories without ratification. India has ratified it in 1979.
Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment
Article 1
- For the purposes of this 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 2
Each State Party shall take effective legislative, administrative, judicial or other measures to prevent acts of torture in any territory under its jurisdiction.
No exceptional circumstances whatsoever, whether a state of war or a threat of war, internal political instability or any other public emergency, may be invoked as a justification of torture.
An order from a superior officer or a public authority may not be invoked as a justification of torture.
Article 16
- Each State Party shall undertake to prevent in any territory under its jurisdiction other acts of cruel, inhuman or degrading treatment or punishment which do not amount to torture as defined in article I, when such acts are committed by or at the instigation of or with the consent or acquiescence of a public official or other person acting in an official capacity. In particular, the obligations contained in articles 10, 11, 12 and 13 shall apply with the substitution for references to torture of references to other forms of cruel, inhuman or degrading treatment or punishment.
The Convention has 173 parties and four more signatories without ratification. India has signed it in 1997, but it was not ratified and thus is not in force.