<![CDATA[This study examines whether disputed amendments to a commercial supply relationship altered or replaced the principal obligation secured by land security rights and how Indonesian courts assessed consent, documentary proof, and enforceability. The research uses a normative juridical method with statutory, case, and conceptual approaches, focusing on a connected litigation sequence: District Court of Tanjungkarang Decision No. 10/Pdt.PLW/2016/PN.Tjk, High Court of Tanjungkarang Decision No. 57/PDT/2017/PT.TJK, and Supreme Court Decision No. 3558 K/Pdt/2018. The analysis distinguishes party allegations from judicially established findings and applies a consistent test to the original obligation, the alleged contractual modification, the continuity of the secured debt, the evidentiary force of authentic deeds, and the burden of proof. The judgments did not establish fraud or a legally effective novation. Instead, they upheld the SKMHT, APHT, and powers of attorney because the challengers did not prove a defect in consent, authority, or the secured relationship sufficient to defeat the instruments relied upon in enforcement. The case also shows that authenticity is evidentiary strength, not immunity from challenge: a party contesting an authentic instrument must direct proof to a legally recognized ground of invalidity and to the relationship between the secured debt and the disputed amendment. The article therefore offers a narrower doctrinal contribution: a structured method for testing contractual variation or novation against the accessory character and evidentiary requirements of Indonesian land security rights.]]>
