Introduction Retailer licensing programmes can be an effective method of enforcing tobacco control laws, but most programmes do not require e-commerce retailers to obtain licenses. California’s implementation of a statewide flavour restriction (Senate Bill 793 (SB-793)) in December 2022 enforced through its tobacco retailer licensing programme presented an opportunity to assess whether the exclusion of e-commerce in the definition of ‘tobacco retailer’ might have resulted in a shift in consumer behaviour towards e-commerce.

Methods To examine the association between SB-793 implementation and online shopping for tobacco, we collected weekly Google search rates related to online shopping for cigarettes and vaping products in California from January 2018 to May 2023. We compared observed rates of shopping queries after SB-793 implementation to counterfactual expected rates and prediction intervals (PI) calculated from autoregressive iterative moving average models fit to historical trends. Content analysis was performed on the search results to identify websites marketing flavoured vaping products and menthol cigarettes.

Results The week SB-793 was implemented, shopping queries were 194.4% (95% PI 100.8% to 451.5%) and 161.7% (95% PI 81.7% to 367.5%) higher than expected for cigarettes and vapes, respectively. Cigarette shopping queries remained elevated significantly for 11 weeks and vape shopping queries for 6 weeks. All search results contained links to websites that offered flavoured vaping products or menthol cigarettes to Californian consumers.

Discussion These findings raise concerns about potential loopholes in policy enforcement created by the absence of explicit regulations on e-commerce sales in retailer licensing programmes. Strengthening regulations to include e-commerce and monitoring e-commerce compliance are recommended to enhance the impact of laws enforced through retailer licensing programmes.