A search incident to arrest is a search conducted by law enforcement personnel when they lawfully arrest a criminal suspect. It is one of a small number or exceptions to laws that prevent or limit law enforcement's ability to search or seize property. A lawful search incident to arrest is usually limited to the person and immediate surroundings of a suspect who is being lawfully arrested.
In much of the Western world, particularly the United States (US), Canada, United Kingdom (UK), and most of Western Europe, there are strong laws that limit the power of law enforcement personnel to invade people's privacy. Protections against unreasonable search and seizure are different in every country, and even vary somewhat between states in the US. Further, though it is common, the allowance for a search incident to arrest is not necessarily universal.
Under the Fourth Amendment to the Constitution of the United States, and subsequent case law, police in the US may not generally search a person or place for evidence of a crime unless the police have a warrant supported by probable cause that has been issued by a proper judicial authority. Evidence discovered or taken by police without a proper warrant cannot usually be presented as evidence in court unless it was obtained under one of a number of exceptions to the warrant requirement. One such exception is the search incident to arrest.
In order for such a search to be proper, the police must first make a lawful custodial arrest. A lawful arrest must normally be supported by a valid warrant. In the absence of a warrant, police may arrest a person if the police have probable cause to believe that a person has committed a felony or certain misdemeanors, or if the person committed any crime in the officer's presence. A custodial arrest generally means that the suspect is at least nominally under the control of law enforcement personnel. This means that a lawful custodial arrest must rise beyond the level of an investigative or Terry stop, which only allows for a pat-down and questioning.
Once a suspect is under lawful arrest, police may search him or her for weapons or other evidence. They may also check his or her immediate surroundings — sometimes called wingspan — including any areas into which he or she might be able to reach for weapons or destroy evidence. This can sometimes include containers carried on the body during or immediately prior to arrest, as well as the interior of a vehicle if the suspect was arrested while inside one. They may also conduct a non-intrusive search, or protective sweep, of a building in order to check for other people who might present a danger to police. Evidence gathered during a valid search incident to arrest is generally admissible in court.