The Fourth Amendment traditionally protects citizens against the unreasonable search and seizure of personal spaces and belongings. Since its inception, the Fourth Amendment has been subjected to unique tests beyond the vision of its original proponents. Today, we can say that judicial interpretation (or what some term activism) from the bench has rendered the United States Constitution a "living" document.
- Under the Fourth Amendment, warrantless searches are not prohibited if it can be shown that there is probable cause for such a search. There are a few major exceptions to the warrant rule, however, including the following:
- Plain view searches: This allows police officers to seize for evidence any object in "plain view" that may be connected to a crime.
- Stop and frisk searches: This allows police officers to pat down an individual for weapons if they have reason to believe the individual may be armed and dangerous.
- The motor vehicle exception: This allows a police officer to search an automobile without a warrant; the officer must have reasonable suspicion about the presence of contraband or illegal items in the automobile. If the car is mobile, the Fourth Amendment does not protect against a warrantless search if police officers deem the vehicle a possible harbor for weapons or contraband pertaining to a crime.
- Consent searches: Police officers can search an individual without a warrant if the individual provides his/ her consent to such a search.
- Search Incident to Arrest (SITA) doctrine: Under this doctrine, police officers may search the vicinity of a crime scene for contraband or weapons after a lawful arrest.
Gant vs. Arizona changed SITA slightly. In its decision on the case, the Supreme Court maintained that the SITA doctrine can only apply in two circumstances. First, the arrestee must be within reaching distance of his vehicle, and second, the officers must have probable cause to believe that the automobile contains evidence that points to the arrest.
In the case of Terry vs. Ohio, a Cleveland detective (McFadden) frisked three men after he suspected them of criminal intent. Weapons were found upon two of the men; one of them, Terry, was convicted of carrying a concealed weapon and sentenced to three years in jail. In an 8-1 decision, the Supreme Court affirmed McFadden's right to search for weapons (in defense of his own personal safety).
Prior to Terry vs. Ohio, New York State passed criminal procedure law 140.50, which stated that a police officer has full rights to detain and search any individual the officer suspects of criminal intent within that officer's jurisdiction. The police officer also has full rights to search such an individual for dangerous weapons if the officer suspects that the officer is in danger of physical injury.