-12 “Solitary confinement can cause serious health problems to the isolated person.” 1.INTRODUCTION Project background This Handbook has been written in the framework of the EU Project “Improving judicial cooperation across the EU through harmonised detention standards - the role of National Preventive Mechanisms”, implemented by the Ludwig Boltzmann Institute of Fundamental and Human Rights, and in cooperation with the Hungarian Helsinki Committee, Bulgarian Helsinki Committee and the Associazione Antigone. The latest case-law of the European Court of Human Rights (ECtHR) as well as recommendations by international and national torture prevention bodies show that no European Union (EU) Member State has eradicated the problem of ill-treatment in prisons, and that there are significant disparities between penal systems within the EU.1 This raises a major challenge for EU cross border cooperation. Judges must verify that fundamental rights, especially the prohibition of torture and ill-treatment, are respected before they can implement mutual recognition instruments.2 The latest available statistics concerning the European Arrest Warrant 1. See ECtHR, The European Court of Human Rights in Facts and Figures: 2019 (2020) <https://www.echr. coe.int/Documents/Facts_Figures_2019_ENG.pdf> pp 10-11. There are 180 cases of violations of Art 3 ECHR in the Council of Europe Member States, 70 of which (as correctly stated in the text) concern EU countries. Those 70 cases translate into 55 direct cases of torture or ill-treatment (under Art 3), 10 cases where states have not conducted effective investigations (under Art 3) and 5 cases where a conditional violation was found (under Art 2/3). 2. Relevant EU instruments are: the Council Framework Decision of 13 June 2002 on the European arrest warrant and the surrender procedures (2002/584/JHA), Recital 12; and the Council Framework Decision 2008/909/JHA of 27 November 2008 on the application of the principle of mutual recognition to judgments in criminal matters imposing custodial sentences or measures involving deprivation of liberty for the purpose of their enforcement in the European Union, Recital 13 and Art 3. See also CJEU, Aranyosi and Căldăraru; Joined Cases C‑404/15 and C‑659/15 PPU, 5 April 2016; CJEU, ML, C‑220/18 PPU, 25 July 2018; CJEU, Dumitru-Tudor Dorobantu. C‑128/18, 15 October 2019; and for a more detailed overview EUROJUST, ‘Case law by the Court of Justice of the European Union on the European Arrest Warrant’ (2020)<https://www.eurojust.europa.eu/sites/default/files/2020-09/2020-03_Case-law-by-CJEUon-EAW_EN.pdf>.