The safeguards of federalism provide state officials with several tools as they try to influence national policy and protect their interests. State legislative challenges to the national government have been widespread recently, yet little is known about their origins. Are they derived from model legislation provided by interest groups, the result of state-to-state emulation, or developed independently by individual states? This article uses plagiarism detection software to offer a preliminary answer to this question. Our analysis suggests that state officials only occasionally rely on model legislation in drafting resistance measures. It also identifies variation across issues. External sources seem to have the greatest impact on legislation resisting gun control, a more modest influence on challenges to the Affordable Care Act, and a minimal effect on state-level responses to Common Core. The article further analyzes these dynamics by examining specific examples of textual overlap among resistance bills in each issue area.