The law of search and seizure governs some of the most basic police investigative techniques.

Including wiretapping and other electronic surveillance, examination of business records, and going through people’s trash, in addition to more traditional techniques such as stopping suspected criminals and searching their clothes, cars, or other belongings.

If criminal procedure was focused entirely on finding the truth and solving crimes, the police would be given wide latitude to engage in searches and seizures. But giving them that latitude would infringe on people’s rights of property, privacy, and personal security. Therefore, the police’s ability to engage in these activities is regulated by the Fourth Amendment to the U.S. Constitution:

“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 Fourth Amendment applies to searches and seizures conducted by any government official, not just a police officer. A public school principal who want to search a student’s locker or a Food and Drug Administration meat inspector who want to inspect a packing plant has to abide by the Fourth Amendment, although the standards of what constitutes an unreasonable search are different in those contexts than with a police office stopping someone on the street. Conversely, the constitutional safe guards only protect against actions by government official. A private employer who want to monitor employees’ e-mail or a department store that installs security cameras in its dressing rooms is not subject to constitutional restrictions.