Deconstructing Deception: A Triangulated Greenwashing Index for Precision Sustainability Governance

Despite decades of research on greenwashing, existing measurement models struggle to distinguish intentional deception from poor performance or to account for how stakeholders interpret corporate claims. This study introduces the Greenwashing Index (GWI), a validated, multidimensional framework that addresses this challenge by integrating linguistic deception (via Bidirectional Encoder Representations from Transformers (BERT)-based natural language processing), verified performance data (e.g., Environmental, Social and Governance (ESG) scores, Environmental Protection Agency (EPA) violations), and stakeholder credibility assessments across investors, consumers, and non-governmental organisations (NGOs). The GWI identifies 83% of regulator-sanctioned firms and correlates strongly with stakeholder-rated greenwashing severity ( r = .71). Cluster analysis reveals four behavioural archetypes, while cross-stakeholder results show NGOs are significantly more punitive than investors. A post-2020 rise in selective disclosure reflects firms’ strategic adaptation to evolving ESG pressures. By bridging intent, action, and perception, the GWI represents a paradigm shift, transforming greenwashing detection from subjective suspicion into scientific diagnosis.