In this Thematic Unit, the principles of extradition of wanted persons and judicial assistance, as important mechanisms of international police and judicial cooperation, will be studied in depth. Reference will be made to the various legal bases for extradition in multilateral and/or bilateral treaties, as well as to national legislation. The various stages of extradition, involving both the judiciary and the executive, will be examined, with an emphasis on police involvement. Human rights issues arising at the various stages of extradition and the international rules regulating them in conjunction with the case law of national courts and the European Court of Human Rights will also be examined. In particular, for legal aid, the followed procedure will be studied both in the context of the European Union and at international (bilateral and multilateral) level. Special forms of legal assistance will also be considered, such as the disposal of illegally acquired items, the transfer of detainees or videoconferencing for interrogation purposes, etc.