This study investigates the 1973 Iranian Environmental Protection and Enhancement Act through the integrated lens of Systemic Functional Linguistics (SFL), ecolinguistics, and Fairclough’s Critical Discourse Analysis (CDA). The aim is to uncover how linguistic choices in the law construct, limit, and reproduce particular environmental realities and ideologies. Using SFL, the research examines experiential, interpersonal, and textual metafunctions as well as grammatical metaphors, providing a detailed account of processes, participants, and cohesive devices. These linguistic findings are then reinterpreted through an ecolinguistic framework to reveal dominant, suppressed, and alternative narratives about environmental governance. Finally, Fairclough’s CDA is applied to connect textual patterns to discursive practices and socio-political structures, exposing the ideological underpinnings of the law. Results indicate that the text privileges a technocratic, state-centered, and economically instrumental view of the environment, marginalizing community-based and ecological-holistic perspectives. The study contributes to understanding how environmental law language both reflects and shapes policy priorities in Iran.