The central theme of Regulatory Law and Policy is the concept that the practice of regulatory law involves the interrelationship of law, policy analysis, and politics. While the legal limits of regulation are explored in many law school courses, this book emphasizes policy analysis and politics. This fourth edition adds two new features. First, it explores contemporary problems such as the legalization of marijuana and the status of rideshare activities of such companies as Uber and Lyft. In addition, we present practice problems for the students to think through and apply the policy analyses discussed throughout the book.