Book excerpt: Public Health Law, first published in 2000, has been widely acclaimed as the definitive statement on public health law at the start of the twenty-first century. Lawrence O. Gostin's definition was based on the notion that government bears a responsibility for advancing the health and well-being of the general population, and the book developed a rich understanding of the government's powers and duties while showing law to be an effective tool in the realization of a healthier and safer population. In this second edition, Gostin analyzes the major health threats of our times, from emerging infectious diseases and bioterrorism to chronic diseases caused by obesity.