Following the previous session, this part of the analysis attempts to illustrate the practical significance of the theory of illegality. The decisive shift of criminal law from the private to public in close connection with public policy can be observed in the early modern period. Thus, the nature of illegality was changed. In other words, the nature of illegality changed “wrong” (i.e., “mala in se” in custom law) to “violation to positive law” (i.e., “mala prohibita” in continental law). However, the role of the theory of illegality can be found in resisting unlawful conducts and unjust law, i.e., “dura lex.” Therefore, the significant role of the theory of illegality is to create just laws by finding the nature of the wrong and to justify the violation to positive law as being necessary. This paper is a preliminary study with the aim to draw a distinction between criminal and civil unlawful conduct and violation of administrative regulations.