Nuancing the conventional wisdom that informal economic activities endure by marginalizing, circumventing, or colluding with the law, we use original court data from China to reveal a counterintuitive mechanism: informal finance can endure through formal litigation. Drawing on 66,843 judicial decisions, case studies of seven top-filers, and interviews, we examine how sophisticated moneylenders, inactive debtors, and embedded courts collectively helped sustain unlicensed moneylending in China before 2020. Moneylenders—whether operating through Fintech or offline channels—leverage superior legal resources to enforce semilegal debts. Debtors facing moneylenders suffer from serious hurdles in accessing justice, especially lacking professional legal help that could potentially change case outcomes. Courts, despite concerns over debtor protection, largely tolerate the semilegal lending in alignment with the pre 2020 regulatory environment that valued the expansion of private financing, particularly through Fintech. Beyond China and the financial market, this litigation-endured mechanism of informal economy reflects a pattern in high-volume civil dockets where litigation is strategically used to bypass regulation, which has contributed to access-to-justice crises in other jurisdictions, including the USA. Theorizing these dynamics raises pressing questions about the institutional role of courts in either sustaining or remedying welfare pathologies, and in shaping a just society.