An Empirical Study on the Regulatory Path and Legal Application of Platform Monopoly Behavior from the Perspective of Commercial Law in the Context of the Digital Economy

To address the concealed nature of platform monopoly behavior and the limited efficiency of commercial-law implementation in the digital economy, this paper constructs an empirical framework for regulatory path analysis and legal application. First, a three-dimensional “subject-behavior-responsibility” framework is developed to define platforms as providers of commercial public infrastructure and clarify their fiduciary duties. Second, 63 typical platform monopoly cases from 2018 to 2024 are collected and coded, covering e-commerce, social media, search, logistics, and online travel platforms across multiple jurisdictions. Third, a dual-test model of “behavioral harm-efficiency defense” is constructed, introducing indicators such as the Herfindahl-Hirschman Index and price transmission elasticity to quantify competitive harm and efficiency justification. Finally, three regulatory paths—ex-ante obligation, ex-post punishment, and commitment to rectification—are compared through a matching matrix. The results show that the ex-ante obligation path achieves a 95% identification rate, a 4.2-month enforcement cycle, and a 14.3% recurrence rate, outperforming alternative paths. The findings support fiduciary-duty-based regulation for platform monopoly governance.