To combat the concern that mandatory arrest laws have resulted in officers unjustly arresting victims, states have enacted primary aggressor laws. Examining 3,078 incidents of intimate partner violence reported to the police in 25 jurisdictions in four states, the authors assess the impact of primary aggressor laws on the likelihood of both single and dual arrest. While dual arrests were more than twice as likely in a state without a primary arrest statute, an arrest was nearly a third less likely in a state with such a statute. The policy implications are discussed.