적대적 M&A 방어와 주주에 대한 충실의무: Unocal 판결의 한국에 대한 시사점

This paper centers on the Unocal decision of the Delaware Supreme Court and aims to demonstrate that the “fiduciary duty to shareholders” serves as the essential criterion for assessing the legitimacy and scope of directors’ defensive measures against hostile takeovers. Although the Unocal ruling is frequently cited in Korea to justify defensive strategies in hostile M&A situations, it clearly establishes that such measures must be based on a rational purpose to protect shareholder interests and must be proportionate to that purpose. However, this legal doctrine presupposes the existence of fiduciary duties owed specifically to shareholders—an obligation not yet recognized under Korean law or prevailing court precedents. Therefore, applying the Unocal framework in Korea would require a legislative shift to broaden the scope of fiduciary duties from being company-centered to shareholder-directed. Nonetheless, many lower court and Supreme Court decisions in Korea reveal a conceptual inconsistency: while maintaining the company-focused duty model confirmed and reinforced by the Everland case, they simultaneously adopt the language and logic of the Unocal decision to justify management’s defensive measures. This approach lacks a coherent legal foundation for assessing the legitimacy of such conduct and undermines the fundamental objective of protecting minority shareholders during M&A transactions. Accordingly, this paper argues, first, that the very concept of a “right to resist takeovers” by directors can only be logically and legally justified if fiduciary duties are extended to shareholders. Second, it seeks to present, through the Unocal decision, a blueprint of how such fiduciary duties toward shareholders could or should operate in practice if codified into law in Korea. Through this analysis, the paper seeks to provide roadmaps for reforming Korea’s corporate law framework and guiding its practical implementation.