The 1992 Declaration for Protection of All People from Enforced Disappearence

The UN Declaration on Enforced Disappearance describes "disappearances" as follows: people "are arrested, detained or abducted against their will or otherwise deprived of their liberty by officials of different branches or levels of Government, or by organized groups or private individuals acting on behalf of, or with the support, direct or indirect, consent or acquiescence of the Government, followed by a refusal to disclose the fate or whereabouts of the persons concerned or a refusal to acknowledge the deprivation of their liberty, which places such persons outside the protection of the law." 

The Declaration on the Protection of All Persons from Enforced Disappearance, adopted by the UN General Assembly in 1992, states that Any act of enforced disappearance is an offence to human  and that it constitutes a “ violation of … the right not to be subjected to torture and other cruel, inhuman or degrading treatment or punishment".