A protective sweep is a type of limited search which the police are legally allowed to conduct when they arrest someone.
For example if the police were called to a home or residence and arrests someone or they believe that someone is hiding in the house and poses a danger to others and the officer or they believe someone may be dead or injured or hiding out of fear in the house or building etc then the police can search the house under the protective sweep law.
The purpose of a protective sweep in law enforcement is to allow police officers to ensure their own safety, and that of those on the scene, by searching in the vicinity of the arrest.
The protective sweep search is for people who may pose a threat.
The Supreme Court found the presumption to be rebutted in the case of searches that fall under the definition of “protective sweep”: “A 'protective sweep' is a quick and limited search of premises, incident to an arrest and conducted to protect the safety of police officers or others.
Under the protective sweep, a police officer can search rooms in a private residence other than those specified in a search warrant, if he has reasonable suspicion that another individual posing a danger to those on the arrest scene is in one of those rooms.
After Chimel v. California (1969), protective sweeps were neither foreclosed nor specifically authorized by the Supreme Court.
While a protective sweep is always a search under the fourth amendment, it is justified by a need to safeguard arresting officers from possible attack from persons other than the arrestee.