It envisaged the establishment of a worldwide system of inspection of places of detention, which later took the form of an Optional Protocol to the UN Convention Against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment (1984).

In 1987, the Council of Europe realized the original idea on a regional level with its European Convention for the Prevention of Torture.

This in turn led to a breakthrough within the United Nations: OPCAT was created and opened for signatures on 18 December 2002 by the UN General Assembly.

[1] As of June 2024[update], 94 states have ratified the protocol: Afghanistan, Albania, Argentina, Armenia, Australia, Austria, Azerbaijan, Belize, Benin, Bolivia, Bosnia and Herzegovina, Brazil, Bulgaria, Burkina Faso, Burundi, Cabo Verde, Cambodia, Central African Republic, Chile, Costa Rica, Côte d'Ivoire, Congo, Croatia, Cyprus, Czech Republic, Democratic Republic of the Congo, Denmark, Ecuador, Estonia, Finland, France, Gabon, Georgia, Germany, Ghana, Greece, Guatemala, Honduras, Hungary, Iceland, Italy, Kazakhstan, Kyrgyzstan, Latvia, Lebanon, Liberia, Liechtenstein, Lithuania, Luxembourg, Madagascar, Maldives, Mali, Malta, Mauritania, Mauritius, Mexico, Mongolia, Montenegro, Morocco, Mozambique, Nauru, Netherlands, New Zealand, Nicaragua, Niger, Nigeria, North Macedonia, Norway, Panama, Paraguay, Peru, Philippines, Poland, Portugal, Republic of Moldova, Romania, Rwanda, Senegal, Serbia, Slovakia, Slovenia, South Africa, South Sudan, Spain, Sri Lanka, State of Palestine, Sweden, Switzerland, Togo, Tunisia, Türkiye, Ukraine, United Kingdom, and Uruguay.

[1] A further 11 states have signed but not ratified the protocol: Angola, Belgium, Cameroon, Chad, Guinea, Guinea-Bissau, Ireland, Sierra Leone, Timor-Leste, Venezuela, and Zambia.