ENArticle 2(1) of the Criminal Code of the Republic of Lithuania (hereinafter, CC) defines the principal of nullum crimen sine lege as an imperative that prohibits the prosecution of a person if his or her actions do not correspond to the composition of the criminal offence or misdemeanour provided for in the criminal law. One of the requirements of criminal law arising from this principle is that the elements of the offence and the formal elements of it should be expressed in the criminal law as clearly as possible, with the aim of properly assessing person’s actions in classifying criminal offences (the principle of nullum crimen, sine lege certa) (Švedas, 2006, p. 81). Such an interpretation of this principle is also enshrined in the case law of the Constitutional Court of the Republic of Lithuania. As stated in the ruling of the Constitutional Court of the Republic of Lithuania no. 7/03-41/03-40/04-46/04-5/05-7/05-17/05, legal regulation established in legal acts must be clear, understandable, non-contradictory, wording of legal acts must be accurate, the internal coherence of the legal system must be ensured, the legal acts must not contain provisions that simultaneously regulate the same public relations in a different way; the law cannot require the impossible; infringements for which liability is established by law must be clearly defined. However, with the ever-increasing amount of criminalised socially unacceptable behaviours that leads to almost casuistic creation of a specific criminal law norm for each of the undesirable behaviours in question, a difficulty of delimiting certain criminal offences in practice arises. One of the main reasons for such an intensive criminalisation could also be linked to the transposition of European Union law into national law. [...] Keywords: crimes against the financial system, composition of the criminal offence, nullum crimen sine lege. [Extract, p. 15-16]