The monograph deals with the special rules of criminal procedure of juveniles in relation to international judicial cooperation between the Member States, the possibility of harmonization, which will culminate in cogitations de lege ferenda. The publication also includes a partial comparison of selected legislation that contains specialized rules of criminal procedure of juveniles, the age of criminal responsibility in these countries and also for his defense of juveniles. The formulation of cogitations de lege ferenda is the creation of a critical analysis of the theoretical basis of legal regulation in the Czech Republic and their confrontation with the decisions of the European Court of Justice, the European Court of Human Rights, national courts and legal arrangements of selected EU countries and their application practices.