Book excerpt: Written by esteemed legal scholar Michael L. Perlin, this indispensable Advanced Introduction examines the long-standing but ever-dynamic relationship between law and mental health. The author discusses and contextualises how the law, primarily in the United States but also in other countries, treats mental health, intellectual disabilities, and mental incapacity, giving examples of how issues such as the rights of patients, the death penalty and the insanity defense permeate constitutional, civil, and criminal matters, and indeed the general practice of law.