Reaffirming that the right to freedom from torture and other cruel, inhuman or degrading treatment or punishment must be respected and protected in all circumstances, and based on the premise that a system of regular visits to places of detention is one of the most effective means to prevent torture and improve conditions of detention, the United Nations adopted on 18 December 2002 a novel international treaty for the prevention of torture: the Optional Protocol to the UN Convention against Torture (OPCAT).

The OPCAT entered into force on 22 of June 2006 and is the culmination of over two decades of joint efforts by civil society and friendly States.

The OPCAT is the first international instrument which seeks to prevent torture and other forms of ill-treatment through the establishment of a system of regular visits to places of detention carried out by independent international and national bodies. International and national bodies will work together to conduct regular visits to all places of detention in all States Parties and will make recommendations to the authorities to establish effective measures to prevent torture and ill-treatments and to improve the conditions of detention of all persons deprived of liberty.

At the international level, the OPCAT creates a new international preventive body, called the UN Subcommittee for the Prevention of Torture. At the national level, States Parties have to create or designate National Preventive Mechanisms (NPMs) within one year of ratification of the OPCAT.

This focus on prevention represents an innovative development within the UN human rights system, as existing UN bodies can only take action on the basis of allegations of human rights abuses. The Optional Protocol also breaks new ground by setting out, for the first time in an international instrument, criteria and safeguards for effective preventive visits by national bodies, ensuring the implementation of international standards at the local level.