If reliable, but uncertain, intelligence predicted a mass casualty terrorist attack and pointed to likely suspects or groups, what preventive actions would properly and constitutionally be authorized? Detention? Interrogation? Threat of torture? Actual torture? What if the attack involved a weaponized virus? Should the government compel massive inoculation that might kill hundreds of people while saving millions? What if an article were about to be published showing how to overcome the inoculation? Should prior censorship of the article be authorized? These are the sort of questions Professor Dershowitz has been asking for more than 60 years, in his teaching, writing and litigating period now, at age 86, he has written his magnum opus, not only confronting these and other tragic choices, but suggesting answers in the form of an over-arching jurisprudential framework to set limits to the increasing power of what he calls the preventive state. “No one but Alan Dershowitz would seek to bring a common mode of analysis to issues as diverse as bail, climate change and terrorism.” (Summers) “Dershowitz makes his case.” (Breyer) This “urgently important book” (Chimerinsky) promises to revolutionize thinking about one of the most important yet often overlooked developments in our age of increasingly cataclysmic threats accompanied by increasingly ineffective, yet dangerously intrusive, tools to predict and prevent these threats. It is the juxtaposition of these phenomenon that give rise to the preventive state and the need for a jurisprudence that provides democratic balance and accountability as both the threats and capabilities increase. Dershowitz’s “masterful analysis” (Goldsmith) should be read by everyone who cares about security, liberty and democracy.