Borobudur Law and Society Journal

Indonesia’s new Criminal Code (Law No 1 of 2023) and new Code of Criminal Procedure (Law No 20 of 2025) have both applied since 2 January 2026, so harmonisation is no longer a reform proposal but a question of how two codes enacted at different times operate together. This normative study asks how the substantive and procedural codes fit one another, what legal and practical obstacles their joint application creates, and what measures can reduce them. Using statutory, conceptual and analytical approaches, it examines the two codes, the adjustment law of 2026, the Supreme Court’s transitional guidance and recent scholarship, and tests the rules against legality, due process, proportionality and accountability. The study finds that the codes are linked mainly through restorative justice, sentencing alternatives, the transitional rule favouring the defendant and the allocation of investigative authority. It identifies four obstacles: thresholds and transitional rules that can be read differently, procedural gaps for new sentencing forms, overlapping investigative roles, and weak judicial control over coercive measures. It recommends implementing regulations, uniform case-handling standards, an integrated case-management system and judicial warrants, and it separates legal inference from empirical claims about implementation.