This article proposes a model to determine the conditions under which GM and non-GM products coexist when the final consumer demand is mostly composed of consumers who are hesitant to purchase GM products. The novelty of this model is that it endogenously considers contamination risks between GM and non-GM products and the resulting consequences in terms of product compliance with regulatory labeling thresholds. The results suggest that a public constraint on private sampling strategies may be a relevant regulatory tool, which has not been considered up until now for the regulation of GM/non-GM coexistence in supply chains. Public intervention related to testing strategies may therefore be used as a substitute for penalties, whose purpose is to punish noncompliant products on the final market.