Population documents, as State Administrative Decrees (KTUN) issued by the Population and Civil Registration Service (Disdukcapil), play a fundamental role in establishing the personal and legal status of Indonesian citizens. However, errors in their issuance — arising from false information, duplicate data, or official oversight — necessitate cancellation mechanisms that uphold material truth and legal certainty. This normative legal study examines the application of the contrarius actus principle in the cancellation of population documents and analyzes the normative conflict between the administrative authority of state officials and the absolute authority of the judiciary. The study finds that the contrarius actus principle, as operationalized under Minister of Home Affairs Regulation Number 108 of 2019, grants the Head of the Population and Civil Registration Service the authority to cancel documents administratively without a court order, particularly for purely administrative errors such as duplicate data and editorial mistakes. However, this application represents a meaningful shift from the classical doctrine of contrarius actus, which emphasizes procedural equivalence rather than mere internal administrative authority. A normative conflict persists between this ministerial regulation and higher-level instruments, including Presidential Regulation Number 96 of 2018 and Law Number 24 of 2013, which require a legally binding court decision for the cancellation of civil registration certificates. The study concludes that regulatory synchronization between the Ministry of Home Affairs and the Supreme Court is essential to clearly delineate administrative from judicial authority in document cancellation, thereby ensuring legal certainty for all citizens.