How is a "search" defined in Fourth Amendment jurisprudence?

In Fourth Amendment jurisprudence, a "search" is defined as any government action that invades a person's reasonable expectation of privacy. This definition is crucial because it establishes a boundary between what constitutes a search requiring probable cause or a warrant and what does not. The reasonable expectation of privacy is determined by societal norms and is evaluated based on whether individuals have a subjective expectation of privacy, which society recognizes as legitimate. This understanding is deeply rooted in case law, particularly in landmark decisions such as Katz v. United States, where the Supreme Court articulated that the Fourth Amendment protects people, not places.

Identifying a search in this manner is essential for analyzing police conduct and ensuring that individuals' rights are protected against unreasonable searches and seizures. It prompts considerations regarding the legality of surveillance, searches of personal property, and other invasions of privacy. Other options presented do not encapsulate the legal framework based on established precedents, as they address different aspects of law enforcement or simply misstate what constitutes a search in the context of the Fourth Amendment.