Analysis of the Legality Principle and Living Law in Society as the Basis for Criminal Punishment under Law Number 1 of 2023

Law Number 1 of 2023 recognizes living law in society as a basis for criminal punishment. This recognition strengthens legal pluralism, yet gives rise to a juridical dilemma because it potentially conflicts with the legality principle, which guarantees legal certainty and the protection of human rights. This study aims to analyze the regulation of living law in society that may serve as a basis for criminal punishment under Law Number 1 of 2023, as well as to examine the forms of incompatibility between the recognition of customary law and the legality principle in criminal law, including its implications for legal certainty. The type of research employed is normative legal research using a statute approach and a conceptual approach. Research data were obtained from primary legal materials in the form of legislation, secondary legal materials in the form of literature and expert opinions, and tertiary legal materials as supplementary sources. Analysis was conducted through descriptive-analytical and qualitative methods, with conclusions drawn deductively and analytically to assess normative consistency and the juridical implications of the provisions under study. The findings indicate that the regulation of living law in society under Law No. 1 of 2023 affirms the state's effort to recognize legal pluralism, yet generates potential incompatibility with the legality principle due to the differing characteristics between customary law—which is unwritten, dynamic, and particular—and modern criminal law, which demands certainty, universality, and written form. The application of customary norms as a basis for criminal punishment also carries implications for legal certainty, as it may give rise to multiple interpretations, the risk of discrimination, and violations of the constitutional rights of citizens if not accompanied by clear filtering mechanisms and normative parameters.