Introduction to the Problem: Marriage annulment under Article 28 of Law No. 1 of 1974 on Marriage generates significant legal consequences for wives who enter into marriage in good faith. Although the provision recognizes legal protection for innocent parties, it does not establish clear criteria for determining good faith, creating legal uncertainty and incosistent judicial protection of wifes’ civil rights. Purpose/Study Objectives: This article examines the legal contruction of good faith in marriage annulment cases and analyses its implications for the civil protection of wives from the perspectives of Islamic law and Indonesian marriage law. Design/Methodology/Approach: This study employs normative legal research using statutory, conceptual, and case approaches. The analysis focuses on Article 28 of the Marriage Law, relevant legal doctrines, and Decision Number 348/Pdt.G/2018/PA.Cbd concerning the annulment of a polygynous marriage. Findings: The study finds that the retroactive effect (ex tunc) of marriage annulment often places good-faith wives in a vulnaerable legal position despite their lack of knowledge regarding defects affecting the validity of the marriage. The ambiguity surrounding the concept of good faith weakens the protection of wives’ civil rights. Drawing upon the principles of al-‘adl, hifz al-haqq, and maqasid al-shari’ah, this article argues that Article 28 should be interpreted through a good-faith-based framework that balances legal certainty, justice, and the protection of vulnerable parties. This study further proposes a reconstruction of the legal meaning of good faith as a basis for strengthening civil protection in marriage annulment cases.