Part of a comprehensive ten-part amendment in 1791 to the 1787 Constitution of the United States and which presents a constutitional protection against unreasonable search and seizure.
The text of the Fourth Amendment is:
"The right of the people to be secure in their persons, houses, papers, and effects, 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 amendment epitomizes the expression "every man's house is his castle".