This thesis investigates the relationship between international trade and environmental law. It does so developing three interconnected arguments. First, this thesis argues that the relationship between the two regimes has undergone a precise evolution. To this end, the trade/environment nexus is framed within the development of both regimes throughout history, and two models are developed to capture this evolution: an exception-based and a promotion- based model. Second, it highlights the discrepancy between the more recent developments in the trade/environment nexus and the prevailing narrative of the trading system, which reflects the exception-based model and which fails to fully capture a system which is increasingly working for the protection of the environment and the promotion of sustainable development goals. Embracing a promotion-based model would instead allow to better explain current development and allow the nexus to further evolve. Finally, the thesis investigates the reasons behind this evolution, emphasizing the importance of ideas and the role that both individuals and communities play in triggering ideational change.