It is easy to identify health laws that have helped Americans live longer, healthier lives. Indeed, most of the greatest public health accomplishments of the last century depended on legal action. The coordination of research, policy development, public education, and advocacy in the tobacco control movement shows that success is attainable even in the face of powerful industry opposition. 1 The development of automobile safety laws during the past 30 years shows how well-conducted, properly diffused research can instigate policy cascades and guide policy refinement over time. 2 These examples of ''interventional health law'' 3-using law as a tool of intervention-also illustrate that developing, enacting, evaluating, and spreading health laws is not just the work of lawyers. In these and many examples like them, health advocates, researchers, public health practitioners, and lawyers work in strategic partnership to improve population health through law and policy. Consistent with the literature on the art and science of evidence translation, 4,5 these efforts were built on effective practices, such as cultivating partnerships among diverse stakeholders. These partnerships promote (1) research that is targeted at the most strategically relevant questions; (2) the development of model laws based on the best available science; (3) sophisticated community education and advocacy campaigns to win, defend, and enforce effective policies; and (4) enforcement to ensure that improved public health outcomes are achieved and sustained. 6-8 The starting point for this commentary is that public health law is not just the work of lawyers but must also be owned by the range of public health disciplines as a transdisciplinary activity. 9 Knowing how to translate what we have learned from research and experience into effective public health law interventions is not the problem. The problem is that the public health system, writ large, does not deploy wellrecognized best practices consistently or strategically across topics. Legal interventions affecting millions of Americans are often not scaled or evaluated for years, if at all. Innovations that show promise in research or practice do not spread, or they spread too slowly. 10,11 The pace can be even slower when innovations are faced with organized ideological or industry opposition. 12 Success requires investment in the same legal infrastructure that was created for tobacco control and alcohol policy and is newly underway in obesity prevention. ''Legal infrastructure'' refers to the people, methods, and tools needed to move a policy from conception to widespread implementation. The first step in establishing this infrastructure is defining its elements. After publication of the 1988 Institute of Medicine (IOM) report The Future of Public Health, 13 public health as a field embarked on an effort to define, measure, and improve the public health system. 14,15 Yet, despite its key role, law largely escaped that systematic treatment. Two of the 10 essential public health services exp...