This comparative report is the result of a two-year research project co-funded by the European Union’s Justice Programme programme and led by the Ludwig Boltzmann Institute of Fundamental and Human Rights in collaboration with partners from Bulgaria, Germany, Italy, Lithuania, and Slovenia. The research examined the implementation of EU Framework Decisions related to judicial cooperation in criminal proceedings, emphasising the rights of defendants and detainees with intellectual and/or psychosocial disabilities. In addition, the research assessed the situation of defendants and detainees with intellectual and/or psychosocial disabilities within the national systems in law and practice and the compliance with international, regional, and national standards, as these factors may impact cross-border cooperation. The project covers procedural safeguards, treatment of persons with intellectual and/or psychosocial disabilities during deprivation of liberty, alternatives to detention and probation measures.