Proceedings of the Annual Meeting of the Cognitive Science Society

An influential legal maxim holds that ignorance of the law is no excuse. While legal theorists have long debated this principle, less is known about laypeople's judgments of ignorant legal violations and the cognitive factors driving them. Across two preregistered vignette studies, we examine how perceived public knowledge of a law shapes blame and punishment judgments toward ignorant agents. Study 1 shows that the exculpatory force of legal ignorance depends strongly on how widely known the law is perceived. The perceived moral wrongness of the prohibited action somewhat moderates this effect. Study 2 shows that ignorance is less excusable when a law is perceived as publicly known, regardless of agents' informational access or whether they are citizens or foreign visitors. Together, the findings suggest that legal ignorance is evaluated under robust epistemic norms centred on what agents are expected to know, rather than on individual differences in access to information.