A/HRC/7/12 page 16 44. Despite these standards, the Special Rapporteur has received numerous reports that in certain cases detention can become prolonged and the detainees subject to ill-treatment. In certain cases irregular migrants have been denied the right to communication, have been subject to physical or sexual assault, have been mixed with detainees charged with criminal offences, and often suffer from a lack of attention to the specific needs of children, women, asylum-seekers and other vulnerable groups.34 45. There seem to be enormous differences between immigration regulations among States, making oversight of detention conditions and States’ adherence to international standards in this practice a challenge.35 Some States entirely lack a legal regime governing immigration and asylum procedures that, when in place, can help to manage detention practices. Others have enacted immigration laws but often they do not provide for a legal framework for detention. Some States have legislation which provides for a maximum period of detention, whereas others are lacking such a time limit. 46. Some national laws do not provide for judicial review of administrative detention of migrants. In other instances, the judicial review of administrative detention is initiated only upon request of the migrant. In these cases, lack of awareness of the right to appeal, lack of awareness of the grounds for detention, difficult access to relevant files, lack of access to free legal counsel, lack of interpreters and translation services, and a general absence of information in a language detainees can understand on the right to instruct and retain counsel and the situation of the facilities where they are being held can prevent migrants from exercising their rights in practice. In the absence of lawyers and/or interpreters, migrants can often feel intimidated and obliged to sign papers without understanding their content. 47. Migrants and asylum-seekers are sometimes detained at airport transit zones and other points of entry, under no clear authority, either with the knowledge of government officials at the airport or simply on the instructions of airline companies before being returned to their countries. The difficulty or impossibility of reaching any outside assistance impedes the exercise of the right of the persons concerned to challenge the lawfulness of the State’s decision to be detained and returned and to apply for asylum, even in the presence of legitimate claims. In practice, some States misleadingly label migrant detention centres as “transit centres” or “guest houses” and “detention” as “retention” in the absence of legislation authorizing deprivation of liberty. 48. Often the legislative criteria of a given State allow for a high degree of discretion in ordering administrative detention: foreign nationals can be detained when immigration officers have “reasonable” grounds to believe that the person is inadmissible, is a danger to the public, 34 Numerous international standards with regard to detention can be found in, inter alia, the ICCPR, CMW, the Vienna Convention on Consular Relations, the Convention on the Rights of the Child. See Amnesty International, “Migration-related detention: a research guide on human rights standards relevant to the detention of migrants, asylum-seekers and refugees”, November 2007. 35 See the various reports to the Commission on Human Rights of the Working Group on Arbitrary Detention (www2.ohchr.org/english/issues/detention/annual.htm).