18 As to the interpretation of Article 4 OP, it is worth noting that the second sentence of Article 4(1) reads: ‘These visits shall be undertaken with a view to strengthening, if necessary, the protection of these persons against torture and other cruel, inhuman or degrading treatment or punishment.’ This sentence reflects the principle of prevention underlying the OP. Regarding the scope of Article 4 OP, the SPT noted that ‘the term “places of detention”, as found in article 4 of the Optional Protocol, should be given a broad interpretation’.29 In its Compilation of Advice, the SPT concretized that ‘[t]he preventive approach which underpins the OPCAT means that as expansive an interpretation as possible should be taken in order to maximise the preventive impact of the work of the NPM’.30
19 As Article 4(1) OP obliges States parties to also allow visits to any place where persons ‘may be deprived of their liberty’, a place falls within the scope of the SPT’s and NPM’s visiting mandate when the SPT or the NPM considers that a person might be deprived of his/her liberty. Therefore, it is only necessary that a place have the potential to de facto limit the right of personal liberty.
20 Article 4 OP explicitly refers to a ‘public or private custodial setting’. The relevant provisions in the two paragraphs of Article 4 seem, however, to contain certain (p. 746) contradictions and are in need of interpretation. Article 4(1) contains an explicit obligation of States parties to allow visits to any place under its jurisdiction and control where persons are or may be deprived of their liberty, ‘either by virtue of an order given by a public authority or at its instigation or with its consent or acquiescence’ while Article 4(2) omits reference to consent or acquiescence by the public authority. However, a systematic interpretation of both provisions, in accordance with the object and purpose of the treaty to provide a comprehensive monitoring of all places of detention, requires that they, as the SPT stated, ‘need to read consistently together and … place within the scope of the Optional Protocol any public or private custodial setting’.31 The SPT noted that an interpretation that is limited to ‘such traditional places of deprivation of liberty as prisons would be overly restrictive and, in the view of the Subcommittee, clearly contrary to the Optional Protocol’.
21 The SPT interpreted the application of the terms ‘consent’ and ‘acquiescence’ in Article 4(1) OP to mean that the scope of the OP includes
any place in which a person is deprived of liberty (in the sense of not being free to leave), or where it considers that a person might be being deprived of their liberty, if it relates to a situation in which the State either exercises, or might be expected to exercise a regulatory function.32
In other words, the conduct of regulating—or the fact that the State should be regulating—creates again the link between the public authority and the place of deprivation of liberty.33 This limits the scope of Article 4 OP regarding purely private places of detention to situations in which individuals are detained by private groups when State authorities are aware of it and fail to exercise due diligence to prevent such detention.34 For example, if the police are aware of the fact that private paramilitary groups are holding people in detention and do nothing in their power to prevent this, they become complicit by acquiescence and the SPT or relevant NPM must be granted access to these facilities. The same holds true for private hospitals or nursing homes, which hold persons against their will with the mere knowledge and consent of a public authority. In any case, the visiting bodies must be granted access to detention facilities which governments have outsourced to private companies.
22 Such a broad interpretation of the scope of Article 4 OP is in line with the CPT’s understanding of the scope of its mandate pursuant to Article 2 ECPT:35
Visits may be organised in all kinds of places where persons are deprived of their liberty, whatever the reasons may be. The Convention is therefore applicable, for example, to places where persons are held in custody, are imprisoned as a result of conviction for an offence, are held in (p. 747) administrative detention, or are interned for medical reasons or where minors are detained by a public authority. Detention by military authorities is also covered by the Convention.36
23 It may be noted that also the comparable provision for the CPT in Article 2 ECPT was interpreted in the Explanatory Report in the sense that
[v]isits may be carried out in private as well as public institutions. The criterion is whether the deprivation of liberty is the result of action by a public authority. Accordingly, the Committee may carry out visits only in relation to persons who are deprived of their liberty by a public authority, and not voluntary patients. However, in the latter case, it should be possible for the Committee to satisfy itself that this was indeed the wish of the patient concerned.37
24 While the term ‘places of detention’ is to be interpreted extensively and an exhaustive list cannot be made, it should include, inter alia:38
25 In the State party to visit, country-specific types of detention as ‘witch camps’ or slum communities50 may be also places of detention to visit. It may, however, be noted that the SPT stated that ‘[i]n any situations, the NPM ought also to be mindful of the principle of proportionality when determining its priorities and the focus of its work.’51 This statement does not suggest a prioritization of traditional places over such that fall under Article 4 OP only because of due diligence obligations; it seems only to intend to clarify that just because a facility fits within the visiting mandate of OP, this does not mean that it should be a priority in its preventive monitoring framework.52
26 Also mobile places such as means of transport are also understood as places of detention. The SPT also noted that ‘the place-based nature of inspecting can miss system-wide problems which require an intersectional approach. It can also fail to monitor instances along the chain of custody, such as transfers and periods of detention immediately after apprehension, where torture and ill-treatment can take place.’53 The SPT recommended that
the State party ensure that all places of detention are included in NPM visits, in accordance with the SPT’s evaluation that all persons deprived of their liberty in a State party are covered by the OPCAT. This includes … periods of deprivation of liberty during apprehension, transfer and removal.54
(p. 749) Hence, in accordance with CAT General Comment No 2, the OP also covers police cars and other means by which individuals are transferred.55 Such deprivation of liberty may be particularly problematic in the context of immigration processes, eg during transfers, disembarkation, and expulsion, as the persons concerned are under high stress and in a very vulnerable situation.56