Using the post-9/11 period as its backdrop, the book examines questions concerning the limits of government intrusion on protected Fourth Amendment rights. From the introduction of the U.S.A. PATRIOT Act and amendments to the Foreign Intelligence Surveillance Act (FISA) to the Terrorist Surveillance Program, the author develops and applies a normative ethical framework based on a legal proportionality test that can be applied to future cases involving U.S. foreign intelligence surveillance.