포털사이트의 알고리즘 변경이 일본 독점금지법상 우월적 지위 남용인지 여부- 최근 타베로그 사건 판결을 중심으로 -

The plaintiff, a company operating twenty-one Korean restaurant chain stores in Japan, initiated civil litigation against Kakachrome Co., Ltd., the operator of Japan’s largest restaurant rating and reservation portal, "Tabelog”(食べログ). The dispute arose from Tabelog’s modification of its restaurant rating algorithm in May 2019. The plaintiff contended that Tabelog deliberately introduced an algorithm that downgraded scores for restaurants operating as chains, which consequently led to a decline in ratings and a substantial reduction in sales across the plaintiff’s restaurants. Alleging discriminatory treatment and abuse of a dominant bargaining position under the Japanese Antimonopoly Act, the plaintiff sought damages and an injunction against the use of the modified algorithm. This case garnered significant attention as the first civil lawsuit challenging the validity of algorithmic modifications on digital platforms, which essentially involve purely mathematical calculation methods. The Tokyo District Court partially accepted the plaintiff’s claim for damages but rejected the request to cease the algorithm’s use. Subsequently, the Tokyo High Court ruled entirely against the plaintiff. Although the case remains pending before Japan’s Supreme Court, it has already prompted numerous academic commentaries, reflecting heightened social interest due to its implications for digital platform regulation. In its appellate decision, the Tokyo High Court held that even if algorithmic changes by portal operators are implemented in ways not explicitly transparent to users, such changes do not constitute an abuse of dominant bargaining position if the purpose and necessity of these adjustments are deemed rational. Platform operators are under no obligation to disclose their algorithms in advance. Thus, for portal users to successfully challenge algorithm changes in court, they must specifically identify which particular algorithmic modification negatively impacted their business. However, it is practically difficult for an individual portal user to precisely ascertain the specific algorithm changes and their impact on their business. This evidentiary burden can be excessively stringent for plaintiffs. The core issue examined in the case was whether Tabelog’s algorithm modification fulfilled the criteria for abuse of dominant bargaining position as defined under the Antimonopoly Act. The litigation revived longstanding debates in Japan regarding the appropriateness of classifying abuses of dominant bargaining position as a form of unfair trade practice regulated under the Antimonopoly Act. Criticism has also increased regarding the application of such abuse-of-position regulations to address market dominance issues. Consequently, the Tabelog case in Japan has encompassed both interpretative questions and legislative policy considerations. Given that South Korea has adopted a regulatory framework for abuse of dominant bargaining positions similar to that of Japan, analogous disputes could arise domestically. This paper has focused primarily on presenting the Japanese case in detail, while proposals regarding legislative and interpretative approaches to algorithmic regulation in South Korea will be explored in subsequent research.