개정 헌법재판소법에 따른 재판소원에서 위헌성 판단상의 주요 쟁점 - 민사재판의 판례변경의 소급효를 제한하는 대법원전원합의체판결 사례를 중심으로 -

초록

The en banc decisions of the Supreme Court of Korea rendered on December 19, 2024 (2020Da247190 and 2023Da302838) abolished the “fixedness” requirement, which had functioned for more than a decade as a central criterion for determining ordinary wages following the Court’s 2013 en banc decision. At the same time, the Court adopted so-called “selective prospectivity,” under which the newly established doctrine was applied retroactively only to the cases before the Court and similarly situated pending cases, while excluding its application to all other cases. Although the decisions appropriately redefined the concept of ordinary wages in accordance with the nature of compensation for regular and contractual work, the arbitrary restriction of the temporal effect of precedent constitutes an impermissible exercise of judicial lawmaking. Moreover, by differentiating workers’ wage claims on the basis of contingent factors such as whether litigation had already been initiated or the timing of judicial decisions, the rulings raise serious constitutional concerns. Historically, there had been no institutional mechanism for challenging judgments of the Supreme Court on constitutional grounds. However, the amended Constitutional Court Act, which entered into force on March 12, 2026, introduced a constitutional complaint against court judgments, thereby opening the possibility of constitutional review over judicial decisions. Against this institutional backdrop, this article examines the doctrinal problems arising from the restriction on retroactivity adopted in the target decisions and explores both the possibility of constitutional complaints challenging subsequent judgments applying such restrictions and the principal constitutional issues likely to arise in constitutional adjudication. The limitation on retroactivity adopted in the target decisions closely resembles the structure of selective prospective overruling formerly recognized by the Supreme Court of the United States. The three-factor balancing framework established in Chevron Oil for limiting the retroactive application of judicial decisions remained influential for approximately two decades. By the 1990s, however, selective prospectivity came under strong criticism on the grounds that it conflicted with the essential nature of judicial decision-making and violated the principle of equality, ultimately leading the Court to return to the general rule of retroactivity. Thereafter, limitations on retroactivity came to be recognized only in exceptional circumstances under highly restrictive standards, while preference was given to case-specific adjustments. In contrast, the examples of prospective overruling adopted by the Korean Supreme Court, including the target decisions, uniformly impose blanket restrictions on retroactive application. Because prospective overruling is fundamentally in tension with the judicial function and carries the risk of infringing constitutional rights such as equality, it requires particularly cautious scrutiny. The selective prospectivity adopted in the target decisions is unconstitutional for several reasons. First, the judiciary’s determination of the temporal effect of precedent amounts to judicial legislation, thereby violating the principles of separation of powers and due process. Second, treating workers in identical legal relationships differently on the basis of accidental factors such as the timing or existence of litigation constitutes discrimination without a reasonable basis and therefore violates the principle of equality. Third, even though less restrictive alternatives—such as the application of the good-faith doctrine or statutes of limitation in individual cases—remain available, the blanket restriction of retroactivity uniformly limits workers’ wage claims and therefore constitutes an infringement of property rights that fails to satisfy the requirements of minimal impairment and proportionality. Fourth, the ambiguity surrounding the scope of “similarly situated pending cases” creates the possibility of arbitrary distinctions and is inconsistent with the constitutional requirement of legal clarity. If constitutional complaints against court judgments operate effectively, they may serve as an important constitutional mechanism for controlling judicial lawmaking. To ensure their effectiveness, however, clear legal standards governing limitations on the retroactive application of judicial decisions must be established, together with legislative reforms concerning subsequent judicial proceedings following decisions sustaining constitutional complaints.

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