Prescribing opioids and other controlled substances is challenging on myriad levels. Beyond the complexities and uncertainties of evaluating and treating patients in pain, the legal landscape is increasingly complicated. Even within the already highly regulated health care environment, opioid prescribing involves additional legal and regulatory constraints. This chapter provides an overview of the legal frameworks for opioid prescribing, including a brief history of opioid regulation in general and for addiction treatment. The federal Controlled Substances Act, Food Drug and Cosmetic Act, and the federal agencies charged with enforcement are reviewed. The chapter also outlines the function, scope, and authority of state professional licensure boards. Clarified definitions of misprescribing are offered and a framework for classifying misprescribers is suggested. Finally, the penalties providers may face for misprescribing in civil court, licensure and discipline actions, and federal and state criminal legal actions are explained.