This article presents an analysis of the criminal offence of Usurpation of plant breeders’ rights –PBR­ (Sect. 306 CP), whose legal definition contains a specific kind of normative terms, namely, theoretical or cognitive or specialized technical element. This analysis seeks to clarify the problems of the mens rea that present themselves when the offense contains normative terms of legal nature. The article seeks to give an answer to the following question: specifically what should be known by the offender regarding a theoretical or cognitive or specialized technical term? The previous question is answered by means of the example of said criminal offence.