Dekonstruksi Asas Legalitas Formil: Mekanisme Pembuktian Living Law dan Tantangan Eksekutorialnya dalam Hukum Acara Pidana Pasca UU Nomor 1 Tahun

Abstract

The enactment of Law Number 1 of 2023 on the Criminal Code and Law Number 20 of 2025 on the Criminal Procedure Code marks a paradigmatic shift in Indonesian criminal justice. Article 2 of the Criminal Code recognises the living law within society as a basis for punishment, partially deconstructing the principle of formal legality (nullum crimen sine lege scripta) that had governed the colonial Wetboek van Strafrecht. This article examines, through a normative juridical method using statutory and conceptual approaches, how that recognition is operationalised after Government Regulation Number 55 of 2025 and how customary offences are to be proven and executed under the new Criminal Procedure Code. It argues that the recognition does not abandon formal legality but re-channels it: an unwritten norm becomes a punishable offence only after being formalised in a regional regulation, so that what appears to be material legality operates, procedurally, as a deferred form of formal legality. The principal problems are evidentiary and executorial. The new evidentiary regime, which abolishes the category of indications and demands authentication and lawful acquisition of evidence, struggles to accommodate the proof of a customary norm whose existence is a normative-sociological fact rather than an ordinary event. Meanwhile, the customary-obligation sanction creates execution difficulties because it depends on communal mechanisms outside the state apparatus. The article concludes that legal certainty and human-rights protection require strict normative parameters, a clear evidentiary standard for expert proof of living law, and an integrated execution scheme.