Skripsi ini membahas bagaimana pelanggaran penerapan prinsip utmost good faith dalam sebuah perjanjian asuransi dapat membatalkan asuransi itu sendiri. Pada skripsi ini pembahasan dibagi tiga. Pertama, pembahasan mengenai pengertian asuransi ditinjau dari Kitab Undang-undang Hukum Dagang, Undang-undang No. 2 Tahun 1992 tentang Usaha Perasuransian, dan Undang-undang No. 2 Tahun 2009 tentang Lembaga Pembiayaan Ekspor Indonesia. Kedua, pengertian prinsip utmost good faith dalam asuransi ditinjau dari Kitab Undang-undang Hukum Dagang dan penerapan prinsip secara umum. Ketiga, pembahasan mengenai pelanggaran prinsip utmost good faith yang dilakukan oleh Alm. Mardi Simarmata berupa penyembunyian fakta material dalam perjanjian asuransinya dengan PT Avrist Assurance. Penelitian ini menggunakan metode yuridisnormatif, dimana data penelitian sebagian besar berasal dari studi kepustakaan. Hasil penelitian ini menyatakan bahwa (1) prinsip utmost good faith merupakan sebuah prinsip yang harus dilaksanakan dalam setiap perjanjian asuransi, (2) perjanjian asuransi antara Alm. Mardi Simarmata dan PT Avrist Assurance merupakan perjanjian yang batal demi hukum, dan (3) Putusan Pengadilan Negeri Tangerang No. 135/Pdt.Plw.BPSK/2012/PN.TNG merupakan putusan yang benar meskipun Majelis Hakim tidak memberikan pertimbangan pada pelanggaranprinsiputmost good faithdalam pertimbangan hukumnya, sedangkan Putusan Mahkamah Agung No. 560K/Pdt.Sus/2012 tidaklah sesuai dengan prinsip hukumasuransi yang berlaku.

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This thesis discusses about how breach of utmost good faith principle nullifies the agreement itself. In this thesis, discussion about the breach is divided into three sections. First, explanation on understanding insurance observed from Business Law Codex, Insurance Business Act, and Indonesian Export Financing Institution Act. Second, explanation on utmost good faith principle in insurance law observed from Business Law Codex and the principle that is applied in general. Third, explanation on breach of utmost good faith principle in the case of The Late Mardi Simarmata against PT Avrist Assurance, wherein The LateMardi Simarmata did a concealment in his agreement with PT Avrist Assurance. This thesis is a normative juridical research, which some of the data of this thesis are based on the related literatures.

From the research, this thesis states that (1) the utmost good faith principle is a basic principle that must be implemented in every insurance agreement, (2) agreement between The Late Mardi Simarmata and PT Avrist Assurance is null and void, which made the heir of The Late Mardi Simarmata, Hermi Sinurat, could not seek for payment of her husband?s insurance, and (3) decision from the Court is right even though the utmost good faith principle was less considered by the judges, whereas Supreme Court?s decision is wrong because it does not fit the legal principles of insurance which is applied in general.