The Fourth Amendment has been held to mean that generally a warrant must be judicially sanctioned for a search or an arrest. In order for such a warrant to be considered reasonable, it must be supported by probable cause and be limited in scope according to specific information supplied by a person (usually a law enforcement officer) who has sworn by it and is therefore accountable to the issuing court. However, a dissenting school of thought often found in the opinions of Justice Antonin Scalia is that searches must simply be "reasonable," and the warrant requirement has been overly emphasized.
The Fourth Amendment applies to governmental searches and seizures, but not those done by private citizens or organizations who are not acting on behalf of a government.[16] The Bill of Rights originally only restricted the federal government. However, in Mapp v. Ohio, 367 U.S. 643 (1961), the Supreme Court ruled that the Fourth Amendment applies to the states by way of the Due Process Clause of the Fourteenth Amendment. Moreover, all state constitutions contain an analogous provision.[17]
Federal jurisdiction regarding criminal law was narrow, until the late 19th century when the Interstate Commerce Act and Sherman Antitrust Act were passed. As federal criminal jurisdiction expanded to include other areas, such asnarcotics, more questions about the Fourth Amendment came to the Supreme Court.[18]
The Supreme Court ruled that some searches and seizures may violate the