Legal scholars have argued that laws have an expressive function, specifically that sexual assault laws may convey social-level messages that victims are culpable for crimes against them. In a university sample, we conducted the first experimental test of legal scholars’ proposal, hypothesizing that legal messages—specifically their clarity and effectiveness in conveying that sexual assault is a crime—affect victim culpability attributions. Results demonstrated that greater culpability was attributed to a victim of sexual assault within a context expressing unclear and ineffective sexual assault law than within a context clearly and effectively expressing that sexual assault is a crime. We also garnered empirical support for a mediation model, that is, negative affective reactions to a victim statistically accounted for the relationship between expressed legal context and victim culpability attributions. Implications for future psycholegal research and potential legal reforms are discussed.