This article’s main aims are to explore, consider and analyse various sources of law to identify the essence and im-portance of the established judicial cooperation system in the European Union (EU) for effective countering of EUthreats and crime. During the research, various sources of European Union Law, case law, constitutional law, etc. wereexplored and considered, by using the analysis method as well as the comparative and synthesis methods. The articlereviews the development of the existing system of judicial cooperation in criminal matters in the EU demonstrating theimportance of the mutual trust involved in the combating of cross-border crime in the EU. Further, it assesses the ef-fectiveness of the existing institute of judicial cooperation in criminal matters in view of combating cross-border crime,in addition to demonstrating the current normative system in the field of judicial cooperation in criminal matters of theEU and its connective side with national criminal justice systems. The main research results highlight the necessity forsupplementing the legal framework of judicial cooperation in criminal matters with a clear definition of the followingterms: cross-border crime and offences with a foreign element, as well as the term foreign element in the context ofjudicial cooperation in criminal matters; the results also shed light on the fact that it is essential to adopt a new legalframework on the transfer of criminal proceedings. Finally, for more effective cooperation among Member States, it isnecessary to approach a common way of the interpretation of the legal acts facilitating correct application and imple-mentation of judicial cooperation in criminal matters instruments in the EU.