Freedom of contract constitutes a cornerstone of private law; however, in contractual relationships characterized by structural or economic imbalance between the parties, this freedom frequently assumes a merely formal character. In situations where one party possesses the ability to unilaterally determine contractual terms, party autonomy often fails to deliver substantive fairness. Within this context, the principle of good faith emerges as an inherent limitation on contractual freedom and serves as a key instrument for achieving contractual justice. The principle of good faith is not confined to the moment of contract formation but operates throughout the entire contractual lifecycle. Its normative function is closely linked to the protection of legitimate expectations and the preservation of trust between the parties. Particularly in pre-formulated contracts, the requirement that contractual content remain within reasonable and acceptable limits necessitates judicial scrutiny grounded in good faith. Such scrutiny reflects the inevitable interaction between contractual autonomy and substantive justice. This study examines the transformative role of the principle of good faith within the tension between formal contractual freedom and material contractual justice. By analysing its interpretative, supplementary, and corrective functions, the article explores the legitimacy and scope of judicial intervention in the determination of contractual content. The analysis aims to construct a coherent theoretical framework in which good faith operates as a systematic mechanism of control, ensuring that contractual relations align not only with formal consent but also with substantive fairness.

Good faith, Contractual justice, Freedom of contract.