Informed by common law practices, the Fourth Amendment protects the "full enjoyment of the rights of personal security, personal liberty, and private property" by prohibiting unreasonable searches and seizures.

Emphasis upon the necessity of warrants places the judgement of an independent magistrate between law enforcement officers and the privacy of citizens, authorizes invasion of that privacy only upon a showing that constitutes probable Cause, and limits that invasion by specification of the person the be seized, the place to be searched, and the evidence to be sought.  Although a warrant is issued ex parte, its validity may be contested in a subsequent suppression hearing if incriminating evidence is found, and a prosecution is brought.

Law enforcement officers must give Miranda warnings PRIOR to "questioning initiated by law enforcement officers after a person has been taken into custody or otherwise deprived of his freedom in any significant way. [Miranda v. Arizona, 384 U.S. 436, 444 (1966)]" Such warnings are thus required when a person is (1) taken into custody, AND (2) subject to interrogation.  The Supreme Court has explained that whether a person is "in custody" depends on the results of a two-part test that considers whether a reasonable person in the suspect's shoes would feel that he could freely exercise his right against self-incrimination and the degree to which the suspect's freedom of action is restricted.