Customary Criminal Law in the New Criminal Code: Between Positive and Negative Functions

The recognition of customary criminal law in Law Number 1 of 2023 concerning the Criminal Code is an important reform in the Indonesian criminal law system. This study aims to elaborate on customary criminal law in the new Criminal Code as a positive and negative function. This study uses a juridical-normative method with a doctrinal approach, focusing on the normative analysis of Article 2 of the Criminal Code and other related provisions. The results of the study show that customary criminal law in the new Criminal Code has two functions, namely a positive function, as a basis for punishment based on the law that lives in society; and a negative function, as a justification that can eliminate the unlawful nature. This provision reflects a shift from the principle of formal legality to the principle of material legality, which is more inclusive of local values. However, its implementation requires caution and compliance with the principles of Pancasila, human rights, and the general principles of the international community.