Which police code represents a request for backup?

The police code that signifies a request for backup is Code 3. This code indicates that an officer is responding to an urgent situation that requires immediate assistance, and it typically implies that responding units should use lights and sirens to get to the scene swiftly. In high-pressure scenarios where an officer might be outnumbered or dealing with a volatile situation, requesting backup is essential for their safety and the efficiency of handling the incident.

On the other hand, the other codes mentioned serve different purposes: 10-4 is a general acknowledgment or agreement, often used in communication to confirm receipt of a message. The code 5150 pertains to a person who may be a danger to themselves or others due to mental illness. Code 459 is used to indicate a burglary. Understanding these distinctions helps ensure clear communication among law enforcement personnel in various situations.