INTRODUCTION 5 rights may be found in all Framework Decisions. Respect for fundamental rights is vital to build mutual trust between the Member States and ensure the good functioning of cross border cooperation. Thus, in order to fully analyse cross-border proceedings, it is necessary to have a look at national systems and identify challenges that arise at the national level related to international, regional and national standards (including EU standards, UNCRPD, UNCAT, ECHR and Council of Europe), which may hinder cross-border cooperation. The project analyses the implementation of the abovementioned EU Framework Decisions into national law with respect to the rights of defendants and detainees with intellectual and/or psychosocial disabilities. So far, little to no attention has been given in research to the specific challenges that these defendants and detainees may face when being subjected to crossborder proceedings. At the same time, the research includes an assessment of 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.