Direct and Indirect Effects of Mandatory GMO Disclosure with Existing Voluntary Non-GMO Labeling

All foods for sale in the US are now required to carry disclosure labels if they contain ingredients with genetically modified organisms (GMOs), but the longstanding and widespread market presence of voluntary non-GMO labels raises questions about their role. Past legislative and voter-initiated measures in several states have proposed mandatory GMO labeling, with Vermont being the only state to successfully pass and implement such a law. We leverage a novel dataset from the Non-GMO Project to examine the direct effect of mandatory GMO labeling and the indirect effect of the associated legislative process on demand for voluntarily-labeled non-GMO products. We show that the legislative process heightened consumer awareness of GMO topics and increased adoption of products with voluntary non-GMO labels, even absent actual implementation of mandatory GMO labeling: about 36% of new non-GMO product adoption can be explained by information environment differences tied to legislative activity. We then utilize implementation of the mandatory GMO labeling law in Vermont as a quasi-experiment to show that in the presence of existing voluntary non-GMO labels, mandatory labeling did not have any additional effect on demand. Our findings suggest that voluntary non-GMO labels may already provide an efficient disclosure mechanism without mandatory GMO labels