Legal Definitions - fellow-officer rule

The fellow-officer rule is a principle in criminal procedure that allows a law enforcement officer to make a lawful investigative stop or an arrest even if that specific officer does not personally possess all the information needed to establish "reasonable suspicion" or "probable cause." This rule applies as long as the officer is acting on reliable information or instructions received from another officer or from the collective knowledge of the entire law enforcement agency, and that collective knowledge *does* meet the necessary legal standard for the stop or arrest. In essence, the knowledge of one officer or the department as a whole can be attributed to the officer taking action.

Here are some examples illustrating the fellow-officer rule:

• Example 1: Traffic Stop Based on a "Be On The Lookout" (BOLO)

  A police dispatcher broadcasts a "Be On The Lookout" (BOLO) alert for a specific vehicle—a green sedan with a dented rear bumper and a partial license plate number—that was reportedly involved in a hit-and-run accident just minutes prior. Officer Thompson, on routine patrol several blocks away, spots a vehicle matching the description. Officer Thompson, who did not witness the accident or speak to any witnesses, pulls the vehicle over to investigate.

  This illustrates the fellow-officer rule because Officer Thompson personally lacked the direct knowledge to establish reasonable suspicion for the stop. However, she was acting on information provided by other officers (via dispatch) who had gathered the initial details of the hit-and-run. The collective knowledge of the department provided the necessary reasonable suspicion for a lawful stop.

• Example 2: Arrest Based on a Detective's Investigation

  Detective Ramirez has spent weeks investigating a series of commercial burglaries and has developed strong probable cause to believe that a suspect, Mr. Jones, is responsible. Detective Ramirez obtains an arrest warrant for Mr. Jones and then informs patrol officers, including Officer Chen, about the warrant and provides a detailed description of Mr. Jones. Later that day, Officer Chen spots Mr. Jones walking down the street and arrests him.

  In this scenario, Officer Chen did not personally conduct the investigation or gather the evidence that established probable cause against Mr. Jones. The probable cause was developed by Detective Ramirez. Under the fellow-officer rule, Officer Chen's arrest of Mr. Jones is lawful because she was acting on the reliable information and the collective knowledge (including the warrant) of her fellow officer and the department.

• Example 3: Undercover Surveillance and Uniformed Intervention

  An undercover surveillance team is monitoring a known illegal gambling operation. They observe a specific individual, Ms. Davis, repeatedly entering and exiting the premises with large sums of cash and interacting suspiciously with known figures in the operation. The surveillance team radios a description of Ms. Davis and her vehicle to a uniformed patrol officer, Officer Lee, who is positioned nearby. Officer Lee, relying solely on the real-time observations communicated by the surveillance team, pulls over Ms. Davis's vehicle a few blocks away to conduct an investigative stop.

  Here, Officer Lee did not personally witness any illegal activity or develop the reasonable suspicion for the stop. That suspicion originated from the observations of the undercover surveillance team. The fellow-officer rule allows Officer Lee to act on the collective knowledge and observations of the law enforcement agency (represented by the surveillance team) to make a lawful investigative stop of Ms. Davis.