"Immigration detainees should only be held in prison establishments when they present specific risk factors that indicate they are unsuitable for immigration removal centres, for reasons of security or control. Immigration detainees will only normally be held in prison accommodation in the following circumstances: • National security – where there is specific (verified) information that a person is a member of a terrorist group or has been engaged in terrorist activities • Criminality – those detainees who have completed prison sentences of 4 years or more, have been involved in the importation of Class A drugs, committed serious offences involving violence, or committed a serious sexual offence requiring registration on the Sex Offenders Register • Security – where the detainee has escaped or attempted to escape from prison, prison or immigration custody, or planned or assisted others to do so • Control – engagement in serious disorder, arson, violence or damage, or planning or assisting others to so engage When a detainee meets the above criteria DEPMU will refer them to the Population Management Unit (PMU) of the National Offender Management Service (NOMS) who will consider their allocation to a prison. … All cases who have completed a prison sentence will be assessed by DEPMU on an individual basis as to whether they should remain in prison or be transferred to an IS removal centre. Any individual may request a transfer from prison to an IS removal centre and, if rejected by DEPMU, will be given reasons for this decision."
"28. On occasion, CPT delegations have found immigration detainees held in Prisons. Even if the actual conditions of detention for these persons in the establishments concerned are adequate – which has not always been the case – the CPT considers such an approach to be fundamentally flawed. A prison is by definition not a suitable place in which to detain someone who is neither convicted nor suspected of a criminal offence. Admittedly, in certain exceptional cases, it might be appropriate to hold an immigration detainee in a prison, because of a known potential for violence. Further an immigration detainee in need of in-patient treatment might have to be accommodated temporarily in a prison health-care facility, in the event of no other secure hospital facility being available. However such detainees should be held quite separately from prisoners, whether on remand or convicted. 29. In the view of the CPT, in those cases where it is deemed necessary to deprive persons of their liberty for an extended period under aliens legislation, they should be accommodated in centres specifically designed for that purpose, offering material conditions and a regime appropriate to their legal situation and staffed by suitably-qualified personnel. The committee is pleased to note that such an approach is increasingly being following in Parties to the Convention. …"
"Custody must be effected in a public establishment specifically intended for this purpose; when, for practical purposes, this is not the case the asylum-seeker or immigrant must be placed in premises separate from those for persons imprisoned under criminal law."
"These special privileges are not absolute and can be tempered by consideration of security, operational need and practical considerations"
"Every detained person may receive as many visits as he wishes within such reasonable limit and subject to such reasonable conditions as the Secretary of State may direct, either generally or in a particular case"