The significant distinction between the actions of the opposing subjects in the crimes regulated under Articles 188 and 191 of the Turkish Penal Code (TPC) related to narcotic substances is based on the purpose of use. Under Art. 191, the purchase or receipt of narcotics with the intent for personal use is considered a separate offense, distinct from the trafficking activities covered under Art. 188. Even though the crimes involving encountering parties are regulated separately as a result of the adopted penal policy, there is a risk that counterpart perpetrators might be linked to the other crime through the general provisions of participation and the principle of accessoriness. Because the interaction between encountering parties may necessitate actions in the form of aiding or abetting, that can be interpreted as leading to accessory liability for the crime of the other party. The jurisprudential inconsistency resulting from this interpretation emerged among the chambers of the Supreme Court of Appeals (Yargıtay) will be comprehensively evaluated in our study in terms of both the right to a fair trial and the principle of legality, particularly in the context of the “prohibition of increasing legal uncertainty”. This inconsistent jurisprudence violates the right to a fair trial and undermines the principles of legality, “nullum crimen, nulla poena sine lege” by violating the “prohibition of increasing legal uncertainty”. Addressing the issue of determining the criminal liability arising from the users’ acts of “instigation”, it is essential to identify a specific structure of necessary participation in the relevant crimes. In our study, we will focus on how this type of crime categorization affects the accessory binding between mutual compulsory contributions and the resulting accessory liability. However, it would be beneficial first to provide a basic explanation of this conceptualization through the different aspects of crimes that require necessary participation. So, we will bring to light the conflict area between compulsory participation and the principle of accessoriness and, reveal the important function of the conceptualization of compulsory participation based on the findings reached in this analysis. Our final conclusion regarding the criminal liability of abettor drug users will provide an opportunity to avoid the problematic application of the principle “the preeminence of perpetration”.