<![CDATA[The authority of Marine Inspectors in conducting ship safety inspections constitutes a fundamental component of maritime governance and administrative law enforcement in Indonesia. However, overlapping institutional mandates and unclear regulatory boundaries have created legal uncertainty regarding the scope of Marine Inspectors' authority, raising concerns over potential ultra vires actions. This study aims to analyze the legal basis and limits of Marine Inspectors' authority from the perspectives of administrative law and the ultra vires doctrine. The research employs a normative juridical method using statutory, conceptual, and comparative approaches. Primary legal materials consist of Indonesian legislation on shipping and state administrative law, while secondary materials include legal doctrines, scholarly publications, and international maritime instruments. The findings demonstrate that Marine Inspectors primarily exercise administrative authority through preventive supervision, compliance verification, certification, and ship safety inspections. Nevertheless, regulatory inconsistencies and overlapping institutional competencies create ambiguity regarding the exercise of inspection powers, potentially leading to actions beyond legally delegated authority. Such conditions weaken legal certainty, administrative accountability, and effective maritime governance. The study concludes that harmonizing maritime regulations, clarifying institutional authority, and strengthening adherence to the principle of legality are essential to preventing ultra vires practices and ensuring an effective, accountable, and legally certain ship safety inspection system.]]>
