This work explores the ways that federalism exacerbates gender inequality among women by explaining the adoption of domestic violence laws across different states in the context of policy diffusion. Using an original dataset of domestic violence firearm law (DVFL) enactments across all 50 states in the United States from 1990 to 2017, we analyze the circumstances under which states will adopt these laws. Using a set of political and demographic indicators as independent variables, we find evidence that state and federal factors influence policy adoption. In particular, the number of gun-related homicides, partisan control of the legislature, citizen ideology, federal policy, and election years each influence the likelihood of DVFL enactments. We find support for the effects of vertical policy diffusion on initial enactment of federal laws in this domain, but not for reauthorizations, which raises important questions about the continuous influence of the federal government on state policies.