Fourth Amendment case law deals with three main issues: what government activities are "searches" and "seizures," what constitutes probable cause to conduct searches and seizures, and how violations of Fourth Amendment rights should be addressed. Early court decisions limited the amendment's scope to physical intrusion of property or persons, but with Katz v. United States (1967), the Supreme Court held that its protections extend to intrusions on the privacy of individuals as well as to physical locations. A warrant is needed for most search and seizure activities, but the Court has carved out a series of exceptions for consent searches, motor vehicle searches, evidence in plain view, exigent circumstances, border searches, and other situations.
The right of the people to be secure in their persons, houses, papers, and effects,[a] against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
The hand-written copy of the proposed Bill of Rights, 1789, cropped to just show the text that would later be ratified as the Fourth Amendment