PatrolSync

A reasonable belief, based on facts and circumstances, that a specific crime has been, is being, or is about to be committed by the person in question. Required to make an arrest or obtain an arrest or search warrant. This is a higher standard than reasonable suspicion.

Source: Foundational 4th Amendment standard

A lower standard than probable cause — specific, articulable facts that, together with rational inferences from those facts, would lead a reasonable officer to suspect criminal activity. Justifies a brief investigative detention (a Terry stop), but not an arrest.

Source: Terry v. Ohio, 392 U.S. 1 (1968)

A brief, limited detention of a person based on reasonable suspicion, allowing an officer to confirm or dispel that suspicion. May include a limited pat-down (frisk) for weapons if the officer reasonably suspects the person is armed and dangerous.

Source: Terry v. Ohio, 392 U.S. 1 (1968)

An emergency situation that justifies a warrantless entry or action that would otherwise require a warrant — for example, imminent danger to life, imminent destruction of evidence, or hot pursuit of a fleeing felon.

Source: Well-established 4th Amendment exception

Miranda warnings are required only when a suspect is both in custody (not free to leave) AND being interrogated (asked questions reasonably likely to elicit an incriminating response) by law enforcement.

Source: Miranda v. Arizona, 384 U.S. 436 (1966)

The legal standard for evaluating an officer's use of force — judged from the perspective of a reasonable officer on the scene, without the benefit of hindsight, based on the totality of the circumstances, not the officer's subjective intent.

Source: Graham v. Connor, 490 U.S. 386 (1989); codified in California at Penal Code § 835a

The legal standard requiring that all facts known to the officer at the time — not any single fact in isolation — be considered together when evaluating probable cause, reasonable suspicion, or use of force.

Source: Well-established legal standard

A private person may arrest another for a public offense committed or attempted in their presence, when the person arrested has committed a felony even if not in their presence, or when a felony has in fact been committed and they have reasonable cause to believe the person arrested committed it.

Source: Penal Code § 837