Katz v. United States (1967)

Over the past century, wiretapping and electronic surveillance have emerged as popular investigative practices among law enforcement agencies in many parts of the world. These investigative practices are governed to some extent, in the United States, by the Fourth Amendment to the Constitution. The Fourth Amendment regulates the ability of government agents to conduct searches or seizures of citizens’ persons, houses, papers, or effects. It explicitly prohibits unreasonable searches and seizures and requires government agents to obtain warrants, based on probable cause, for all searches or seizures that would otherwise be considered “unreasonable.” The U.S. Supreme Court has held that searches, for Fourth Amendment purposes, may be physical or electronic in nature. In a decision from 1967, Katz v. United States, the Supreme Court held ...