Public health law and public health policy are fundamental tools that assist states in the task of protecting people from threats to health, preventing disease, and striving for healthy populations. This paper examines their respective and joint roles in influencing health outcomes. It considers definitions and theories of 'public health law' and 'public health policy', explores the relationship between law and policy, and provides examples of public health law and policy as dual mechanisms for public health. The limits and bounds of the law as a public health tool are also discussed highlighting where policy may be more effective in achieving particular aims. Supranational and international public health law and policy is also considered, emphasizing the importance of laws and policies that transcend national domains. The important roles of bodies beyond government, including inter-governmental organizations, business, and civil society, are noted, recognizing all may influence and effect law, policy, and practice, and in turn, public health.