persons are de facto detained, for example individuals who in practice are unable to leave of their own free will and over whom the States exercise a regulatory function. The preventive approach underpinning the Optional Protocol means that the interpretation of “places where the persons are or may be deprived of their liberty” should be as extensive as possible in order to maximize the preventive impact of the work of NPMs. The Optional Protocol does not contain any lists of places of deprivation of liberty and purposefully adopts a broad, open-textured approach. CHECKLIST: ILLUSTRATIVE EXAMPLES OF PLACES OF DEPRIVATION OF LIBERTY (NON-EXHAUSTIVE LIST) ;; police stations ;; pre-trial detention centres ;; remand prisons ;; prisons ;; juvenile detention centres ;; border police facilities and transit zones at land crossings, international ports and airports ;; immigration and asylum seekers’ detention centres ;; psychiatric institutions ;; security and intelligence service facilities ;; detention facilities under military jurisdiction ;; places of administrative detention ;; means of transport for the transfer of detainees ;; social care homes provided by the State or subject to State regulations or licensing ;; unofficial places of detention (such as those operating secret detentions) ÎÎNPMS AND CROSS-BORDER MONITORING OF PERSONS IN DETENTION There might be occasions when States parties to the Optional Protocol (sending States) enter into arrangements under which those detained by the States are held in facilitates located in other States (receiving States). In these cases, the SPT recognizes that sending States should ensure that such agreements provide for NPMs to have the legal and practical capacities to visit those detainees in accordance with the provisions of the OPCAT and the SPT guidelines on National Preventive Mechanisms. In addition, NPMs of the receiving States should also have the capacity to visit those in detention based on such agreements, as a natural consequence of fulfilling their mandates. After undertaking such visits, the NPMs of the sending States and/or the NPMs of the receiving States should be able to present their recommendations and enter into preventive dialogue with the authorities of both the sending and receiving States. Agreements entered into between the sending and receiving States should provide for the NPMs’ collaboration and permit variations in the terms thereof, in the light of the recommendations made. The two NPMs should liaise on the conduct of such visits and consider making joint visits and recommendations.10 10 Ninth annual report of the Subcommittee on Prevention of Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment, CAT/C/57/4, Annex: Compilation of advice provided by the Subcommittee in response to the request of the National Preventive Mechanisms (Compilation of advice by SPT to NPMs), p. 22. FREQUENTLY ASKED QUESTIONS I 7