T The customary practice of using foreign languages in marine insurance contracts potentially triggers legal issues, as it contradicts the mandatory use of the indonesian language stipulated in article 31 of law number 24 of 2009 and article 26 of presidential regulation number 63 of 2019. the absence of explicit sanctions within these regulations creates a normative vacuum, thus raising research questions regarding the legal standing of utilizing non-bilingual foreign languages in marine insurance policies in indonesia, as well as its legal consequences on the validity of the rugun lata vessel insurance policy. this study is a normative legal research employing a descriptive-analytical approach to address the aforementioned issues. data collection was conducted through library and document research utilizing secondary data, which was subsequently analyzed employing a normative-qualitative method with deductive reasoning. the research findings indicate that the substance of the rugun lata vessel insurance policy is predominantly composed of english clauses. although this does not nullify the validity of the policy (article 1320 of the indonesian civil code), it potentially diminishes legal certainty and legal protection. in the event that the absence of an indonesian version causes detriment to the insured, such a circumstance may be qualified as an unlawful act (article 1365 of the indonesian civil code). therefore, it is recommended that every substantive clause in the policy is accompanied by an equivalent indonesian counterpart without derogating from international standards.