Refugee Survey Quarterly  43 detrimental impact of detention on the health of migrants and asylum-seekers.8 The widespread and systematic application of immigration detention is also vehemently challenged by human rights groups as it compromises fundamental human rights, particularly liberty and safety, while failing the tests of necessity and proportionality.9 More recently, immigration detention has been challenged in terms of cost-effectiveness, in particular when compared with alternative measures.10 Médecins Sans Frontières (MSF) is one of a handful of international humanitarian agencies that has worked in immigration detention settings, and it has publicly shared its strong concerns over the detrimental impact of detention on migrants’ health and well-being.11 It is less often acknowledged, however, that working with detainees poses unique challenges and dilemmas, especially for an organisation committed to classical humanitarian principles, such as independence, which dictates that humanitarian action must be autonomous from the political, economic, military, or other objectives that any actor may hold with regard to areas where humanitarian action is being implemented. This article discusses MSF’s experiences of working with detained migrants and asylum-seekers in Greece, focusing in particular on the constraints, challenges, and dilemmas it has faced. It argues that the main issues have been access, acceptance, accountability, relevance, and efficacy. First, unrestricted access is impossible, bringing into question the application of the principle of independence. Secondly, when access is granted, MSF teams risk being perceived as collaborating with the detention system, raising issues of acceptance and accountability. Thirdly, the impact of MSF’s work can only be limited in such constrained conditions, raising problems of relevance and effectiveness. The article draws primarily on the author’s experience working on projects with detained migrants and asylum-seekers in Greece over a period of five years between 8 K. Robjant, R. Hassan & C. Katona, “Mental Health Implications of Detaining Asylum Seekers: Systematic Review”, The British Journal of Psychiatry, 194, 2009, 306–312. Z. Steel et al., “Impact of Immigration Detention and Temporary Protection on the Mental Health of Refugees”, British Journal of Psychiatry, 188, 2006, 58–64; G. J. Coffey, I. Kaplan, R. C. Sampson & M. Montagna Tucci, “The Meaning and Mental Health Consequences of Long-Term Immigration Detention for People Seeking Asylum”, Social Science and Medicine, 70, 2010, 2070–2079; A. Lorek et al., “The Mental and Physical Health Difficulties of Children Held within a British Immigration Detention Center: A Pilot Study”, Child Abuse & Neglect, 33, 2009, 573–585; A. S. Keller et al., “Mental Health of Detained Asylum Seekers”, Lancet, 362, 2003, 1721– 1723; J. Cleveland, “Psychological Harm and the Case for Alternative”, Forced Migration Review, 44, 2013, 7–8. 9 UNHCR, Detention Guidelines. 10 D. Angeli, A. Triantafyllidou & A. Dimitriadi, Assessing the Cost-effectiveness of Irregular Migration Control Policies in Greece, Migration and Detention Assessment (MIDAS), Report, 2014, available at: http:// www.eliamep.gr/wp-content/uploads/2014/11/MIDAS-REPORT.pdf (last visited 22 Feb. 2016). 11 MSF, Invisible Suffering: Prolonged and Systematic Detention of Migrants and Asylum Seekers in Substandard Conditions in Greece, MSF, 2014, available at: http://www.msf.org/sites/msf.org/files/invisible_suffering.pdf (last visited 22 Feb. 2016); MSF, Torture, Exploitation and Abuse of Migrants in North Africa, MSF, 2011, available at: http://association.amsterdam.msf.org/sites/default/files/file/ChouchaMHfinal%20Small.pdf (last visited 22 Feb. 2016); MSF, Over the Wall: A Tour of Italy’s Migrant Centres, MSF Italy, 2010, available at: http://www.msf.org. br/sites/default/files/80.pdf (last visited 22 Feb. 2016); MSF, Migrants in Detention – Lives on Hold, Athens, MSF Greece, 2010, available at: http://www.doctorswithoutborders.org/sites/usa/files/Migrants-in-GreeceReport.pdf (last visited 22 Feb. 2016); MSF, “Not Criminals”: Médecins Sans Frontières Exposes Conditions for Undocumented Migrants and Asylum Seekers in Maltese Detention Centres, Brussels, MSF, 2009, available at: http://www.meltingpot.org/IMG/pdf/Report_Malta_04_2009.pdf (last visited 22 Feb. 2016).