Populist Leadership and Environmental Policy Stringency: Evidence From 40 Countries (1995–2020)

ABSTRACT Populist leadership poses new challenges to institutionalized environmental governance, raising concerns about whether such governments erode de jure environmental law or primarily weaken de facto enforcement. This study examines the relationship between populist rule and de jure environmental policy stringency (EPS) across 40 countries from 1995 to 2020, employing the Organization for Economic Co‐operation and Development (OECD)‐coded EPS Index as a measure of formally codified regulation. The analysis applies a two‐way fixed‐effects (2WFE) model to estimate within‐country changes in OECD‐coded EPS under populist incumbency while controlling for institutional, structural, and economic conditions. Robustness checks employ descriptive difference‐in‐differences (DiD) visualization, lagged specifications to capture delayed effects, heterogeneity tests across market‐based, non‐market‐based, and technology‐support sub‐indices, and dynamic System Generalized Method of Moments (System GMM) estimation addressing potential persistence and endogeneity. Results indicate that populist leadership, whether left‐ or right‐wing, has no statistically significant association with changes in OECD‐coded EPS. The findings reveal strong institutional inertia and policy path dependence, as de jure environmental frameworks remain resilient to short‐term political disruption. Nevertheless, this formal stability does not ensure comprehensive protection, since populist administrations can still undermine enforcement and administrative capacity. Policy attention should therefore prioritize maintaining bureaucratic autonomy, ensuring stable agency funding, and leveraging persistent de jure frameworks to sustain environmental integrity under populist governance.