Due to the thousands of daily governmental intrusions such as airport checks, traffic stops, drug testing, obtaining of digital evidence, traditional criminal law enforcement practices and regulatory inspections the Fourth Amendment is the most commonly implicated and litigated part of our Constitution. This treatise comprehensively treats United States Supreme Court caselaw and takes a structural approach to the Fourth Amendment, addressing foundational questions, such as: What is a search? What is a seizure? What does the Amendment protect? Who does it protect? When is it satisfied? When does the exclusionary rule apply? The treatise is organized by topic so a reader can have ready access to current doctrine and is able to examine in additional sections how current doctrine developed. The historical events and the Court's development of search and seizure principles provide context to, and perspective on, current doctrine.