In demonstrating that and how international regimes facilitate the convergence of foreign policy positions, analysts typically depart from irregularities at the macro-level and focus on beneficial effects for cooperation. This paper shows, with reference to the post-Treaty negotiations on an “Access and Benefit-Sharing” regime under the Convention on Biological Diversity, that standard approaches to substantiating regime effects on the output dimension fail to capture “perverse” regime impacts on perpetuating disagreement and “positive” effects that are overshadowed by malign conditions for cooperation. While this shortcoming may be acceptable in making a case for institutional causation across cases, it severely limits the analytical purview when the goal is the evaluation of a specific regime’s performance under historical circumstances. This paper outlines the contours of an alternative, more inclusive approach to the “output effectiveness” of international regimes. It firmly locates the analytical focus on the state level to investigate regime impacts on changes in foreign-policy making irrespectively of their implications for and impacts on collective action. By drawing on bargaining theory and foreign policy analysis, causal pathways for regime influence can eventually be formalised that would not only provide a standardised framework for tracing specific regime effects of varying quality, but also allow for their comparative assessment within the same research design.