executive summary Mutual recognition and mutual trust as a basis for cooperation in criminal matters in the EU This Study developed during the course of a critical time for the European Union. A crucial time for enhancing and supporting mutual trust and recognition, but equally a time recognising the priorities of the Union not only rooted as an economic entity but also one firmly committed to safeguarding the fundamental rights of its citizens. Over the last decade, criminal justice has increasingly played a significant role in the operation of the EU. To this end, and with a view to guaranteeing an area of freedom, security and justice within its territory, the EU has established systems of cooperation between Member States, as well as common minimum standards. In order to ensure the effectiveness of national criminal laws despite the removal of internal borders, a number of EU legal instruments were introduced to foster cooperation in criminal matters. This Study centres around the Framework Decision on the European Arrest Warrant (FD EAW), and three of the key Framework Decisions on detention, namely the Framework Decision 909 on the Transfer of Prisoners, (FD TOP) Framework Decision 829 on the European Supervision Order (FD ESO) and Framework Decision 947 on Probation and Alternative Sanctions (FD PAS). These mutual recognition instruments involve a process of judicial decision making whereby a decision taken by a judicial authority in one EU Member State is given effect in another EU Member State. Mutual recognition is essential for effective cross-border cooperation and the practical implementation of EU instruments. It is based on a principle of mutual trust – an understanding that each Member State can and should trust that all the other Member States respect fundamental rights standards, as is a prerequisite to membership of the EU. The underlying principle rooted in the fact that although the various legal systems differ, they provide equivalent and effective protection of fundamental rights. While in many ways these Framework Decisions are crucial to effectively address crime in the EU, they also raise fundamental rights concerns that must be borne in mind. The focus of this Study relates to fundamental rights concerns particular to Article 3 ECHR, and Article 4 CFREU, which provide for the absolute prohibition of torture and ill-treatment. Other fundamental rights will be referenced to, where relevant to the prevention of ill-treatment, but will not constitute the focus. From the outset, it is worth noting that none of the Framework Decisions contain a specific fundamental rights based refusal ground as a basis to refuse to execute an EAW or the Framework Decisions on detention. This can be contrasted with the Directive on the European Investigation Order which does make such a specific reference to Fundamental Rights. As a result, many member states have formulated fundamental rights based refusal grounds within their implementing legislation, or have sought, through jurisprudence, to elaborate safeguards. The Framework Decisions on Detention as a challenge to the prevention of ill- treatment As mutual recognition is the bedrock of the functioning of the European Union, mutual trust, which enables it, must therefore be the starting point for any judge presented with an EAW to execute, or is required to determine upon the transfer of a prisoner from EU Member State to another. However, as is often the case, a disparity exists between theory and practice, and this is particularly evident in the context of detention conditions. Notwithstanding minimum standards and accepted practice, prison conditions vary greatly between the Member States of the EU. Jurisprudence across Europe shows that fundamental rights are not always respected uniformly in each Member State. To this end, there has been a significant body of case law emanating from the Court of Justice of the 7