<![CDATA[Good faith is one of the oldest and most contested organizing principles of contract law, standing at the intersection of moral aspiration and binding legal obligation. This article compares how the principle of good faith, known in Indonesian legal discourse as itikad baik, operates within Indonesian civil law under Article 1338 paragraph (3) of the Indonesian Civil Code, and how functionally equivalent doctrines operate in selected civil law and common law jurisdictions, including the Netherlands, Germany, France, England, China, Japan, and Kazakhstan, as well as within transnational instruments such as the United Nations Convention on Contracts for the International Sale of Goods and the UNIDROIT Principles of International Commercial Contracts. Using a normative juridical method supported by comparative and conceptual legal approaches, the study traces the doctrinal evolution of good faith from a narrowly performance-stage obligation toward a principle that increasingly governs precontractual negotiation, formation, and post-contractual conduct. The findings show that Indonesian courts have gradually broadened the temporal and substantive reach of itikad baik well beyond the literal wording of the Civil Code, yet the concept remains normatively underdefined, producing inconsistent judicial reasoning and legal uncertainty for commercial actors. Comparative analysis further reveals that civil law systems generally codify good faith as an open-textured general clause capable of judicial concretisation, whereas common law jurisdictions continue to resist a unified doctrine, preferring incremental and context-specific recognition through implied terms and relational contract theory. The article concludes that Indonesia's ongoing civil code reform agenda would benefit from clearer statutory benchmarks for good faith, informed by comparative best practice and international harmonisation instruments, in order to enhance legal predictability, deter opportunistic conduct, and strengthen Indonesia's competitiveness in cross-border commercial transactions]]>
