In democracies, legal advocacy is known to channel social movements into narrower, less radical paths. However, the extent and conditions under which law co-opts social movements in nondemocratic contexts remain less clear, particularly given the constraints of underdeveloped legal systems and the frequent blending of legal and nonlegal mobilization tactics among societal actors. This Article examines environmental legal mobilization in China as a case study, illustrating how a discriminatory legal opportunity structure—where the judiciary provides a powerful platform for advocacy, yet access and affordability are limited to those demonstrating state-aligned behaviors—serves as an effective mechanism of co-optation under authoritarianism. By permitting environmental NGOs to engage in public interest litigation while tightly regulating their legal standing and financial resources, the party-state has led NGOs to self-moderate their goals and tactics, deepen their fiscal and political dependence on the party-state, and foster divisions among advocacy groups. This Article underscores the nuanced interplay between authoritarian legality and social movements, demonstrating how legal opportunity structures can be strategically engineered to limit the transformative potential of these groups.