A/HRC/22/44 detention is a personal right, which must “in all circumstances be guaranteed by the jurisdiction of the ordinary courts.”41 72. Counter-terrorism legislation that permits administrative detention often allows secret evidence as the basis for indefinite detention. As this would be inconsistent with the prohibition of arbitrary deprivation of liberty, no person should be deprived of liberty or kept in detention on the sole basis of evidence to which the detainee does not have the ability to respond, including in cases of immigration, terrorism-related and other subcategories of administrative detention. The Working Group has held that, even if lawyers of the detainee have access to such evidence but are not allowed to share or discuss it with their client, this does not sufficiently protect the detainee’s right to liberty.42 73. The Working Group also reiterates that “the use of ‘administrative detention’ under public security legislation [or] migration laws … resulting in a deprivation of liberty for unlimited time or for very long periods without effective judicial oversight, as a means to detain persons suspected of involvement in terrorism or other crimes, is not compatible with international human rights law”.43 The practice of administrative detention is particularly worrying as it increases the likelihood of solitary confinement, acts of torture and other forms of ill-treatment. 74. Even though administrative detention per se is not tantamount to arbitrary detention, its application in practice is overly broad and its compliance with the minimum guarantees of due process is in the majority of cases inadequate. 75. In conclusion and in the light of the foregoing, the Working Group on Arbitrary Detention finds that all forms of arbitrary deprivation of liberty, including the five categories of arbitrary deprivation of liberty as referred to above in paragraph 38, are prohibited under customary international law. The Working Group also concludes that arbitrary deprivation of liberty constitutes a peremptory or jus cogens norm. IV. Conclusions 76. The Working Group, in the fulfilment of its mandate, welcomes the cooperation it has received from States with regard to the responses by the Governments concerned concerning cases brought to their attention under its regular procedure. During 2012, the Working Group adopted 69 opinions concerning 198 persons in 37 countries. It also sent 104 urgent appeals to 44 countries concerning 606 persons (including 56 women). 77. The Working Group welcomes the invitations extended to it to pay visits to countries on official mission. The Working Group conducted an official visit in 2012 to El Salvador. Among all the requested country visits, the Working Group has received invitations from the Governments of Argentina (for a follow-up visit), Azerbaijan, Brazil, Burkina Faso, Greece, India, Japan, Libya, Spain and the United States of America. It has also requested to be invited to other 20 countries. The Working Group reiterates its belief that its country visits are essential in fulfilling its mandate. For Governments, these visits provide an excellent opportunity to show developments and progress in detainees’ rights and the respect for human rights, including the crucial right not to be arbitrarily deprived of liberty. 41 42 43 24 Ibid., para. 85. Working Group, opinions Nos. 5/2010 (Israel) and 26/2007 (Israel). Report of the Working Group, E/CN.4/2005/6, para. 77. GE.12-18935