Why do political systems introduce lobbying rules? Previous literature has analysed the determinants of the introduction of lobbying laws in the US states. However, the last 15 years have witnessed a booming popularity of lobbying laws across the world. Building upon the existing literature, this study seeks to explain the introduction of lobbying laws in EU and OECD member states from 1995 to 2014. The analysis considers variables related to the presence of lobbying scandals, the external promotion by international organizations and corporatism. The causal mechanisms follow the theoretical arguments developed in the literature on political agenda-setting effects, policy diffusion and theories of interest representation. The empirical investigation is based on an original dataset and a statistical investigation using event history analysis and multinomial regression models. The results suggest that policy diffusion variables influence the likelihood of passing lobbying laws. While scandals only affect the presentation of proposals for lobbying regulation in Parliament, corporatism shows no effects on the passage of such laws.