This casebook, in a logical and student-friendly format, presents the challenges that terrorism poses to the law. The decisions of Congress, the President, and the courts are organized around various counterterrorism strategies and processes. Strategies used in the United States are compared with those of other nations. The cases and notes explore fascinating issues seldom found elsewhere in law schools such as, crimes punishing speech; warrantless searches and seizures; data mining; foreign intelligence surveillance; extraordinary rendition; state secrets; lengthy military detention; enhanced interrogation techniques; unusual trial forums and processes; targeted killings; immigration sweeps; and compensation barriers. Illustrations include: boundary-blurring between criminal and military law reconsideration of traditional detention and interrogation practices mingling of investigation and intelligence-gathering exceptions to constitutional protections of individual rights new fault lines between courts, the executive, and Congress modifications to the law of armed conflict revisions to immigration law unique aspects of compensation systems related to terrorism. The book is structured into the following chapters and topics: Chapter I provides a broad brush introduction, primarily non-legal, to terrorism and counterterrorism, a short substitute for an undergraduate overview of this field. Chapters II and III explore antiterrorism criminal law (including punishments) and criminal procedures related to finding terrorists. Chapter IV then examines in detail a specific investigatory tool, foreign intelligence surveillance. Chapters V-VII present the legal battles over civilian and military detention and interrogation of alleged terrorists and the processes (mainly habeas corpus) for ending detention. Trial processes concerning defendants charged with terrorism offenses are treated in the context of both civilian trials (Chapter VIII) and military commission proceedings (Chapter IX). Chapter X explores the allocation of authority in the United States to deal with terrorism, followed by Chapter XI, which examines international law constraints on the use of military force as a counterterrorism tool. Finally, Chapters XII and XIII consider, respectively, the immigration system as a counterterrorism shield and civil liability as a tool for making terrorists and their supporters, as well as counterterrorism officials, pay for harm to individuals.