Massachusetts State House.
Boston Bar Journal

Commonwealth v. Privette: SJC Reins In the Fellow Officer Rule

November 07, 2023
| Fall 2023 Vol. 67 #4

By John Hayes

In Commonwealth v. Privette,[i] the Supreme Judicial Court (“SJC”) reconsidered and substantially limited its previous formulation of the horizontal collective knowledge doctrine, often colloquially known as the “fellow officer rule.”[ii] With Privette, the SJC reined in its permissive application of the fellow officer rule and set new conditions limiting the circumstances in which the Commonwealth can invoke the rule.

Before Privette, when considering the warrantless stop of a suspect, Massachusetts courts imputed the knowledge of any officer involved in a cooperative investigation to the officer making or requesting a stop (the “acting officer”), even if the acting officer did not know that information, and even if the officers were not in communication. This allowed the aggregation of information known to any police officer to the acting officer in determining whether the stop was justified. The collective knowledge doctrine only required that the officers engaged in a cooperative effort; the doctrine imposed no requirement that the information supporting the stop or seizure be conveyed to any of the officers involved in the cooperative effort. As the SJC reasoned, “the knowledge of each officer is treated as the common knowledge of all officers.”[iii]

The Privette court recognized that its prior expansive interpretation of the collective knowledge doctrine was the minority view. Most federal and state jurisdictions require that the information supporting reasonable suspicion or probable cause be conveyed to the acting officer prior to the stop or seizure.[iv] Other jurisdictions require communication amongst officers to establish that they are engaged in a joint effort, but do not require explicit communication to the acting officer of the facts supporting the stop or seizure.[v]

With Privette, the SJC moved the Commonwealth closer to the majority view. The SJC applied article 14 of the Massachusetts Declaration of Rights to limit application of the collective knowledge doctrine and impose stricter conditions on when information may be aggregated and imputed to the acting officer. Privette holds that four requirements must be met before information supporting a warrantless stop or seizure can be aggregated and imputed to the acting officer:[vi]

  1. The officers must be engaged in a joint investigation, with a mutual purpose and objective;
  2. The officers must be in close and continuous communication with each other about that mutual objective;
  3. The acting officer must have knowledge of at least some of the critical facts giving rise to reasonable suspicion or probable cause, but the acting officer need not have knowledge of all of those facts; and
  4. The acting officer must have been in communication with others who have such knowledge.[vii]

When these conditions are met, the knowledge of any one of the officers in the investigatory team will be imputed to all the officers in that team.

What is not required for the collective knowledge to apply after Privette? First, the acting officer does not have to know all the information that forms the legal basis for a stop. Second, all that information does not have to be contained in the information dispatched or shared with any of the officers in the team (as long as one officer knows it). Third, all that information need not have inevitably become known to the acting officer. Privette merely requires that the aggregated information known to officers involved in a joint investigation justified the stop or seizure, and that the acting officer knew some of the critical information.

As such, while Privette limits the reach of the collective knowledge doctrine, the SJC nevertheless maintained the legal fiction that the aggregate knowledge of the investigative or pursuit team may be imputed to the acting officer. The SJC justified this fiction on the need to balance the right of individuals to be free from unreasonable seizures with the practical needs, realities, and risks incumbent in a police operation that is unfolding moment to moment, in “dynamic environment(s) marked by the potential for violence.”[viii] The SJC reasoned that the Privette requirements appropriately balance the right of “the suspect to be free from unreasonable searches, with the need of law enforcement and the public to stop someone who is fleeing the scene after having committed a violent crime before further violence is visited upon the public.”[ix]

In reaching this conclusion, the SJC repeatedly discussed the collective knowledge doctrine in the context of the “hot pursuit of fleeing suspects,”[x] and justified the doctrine by balancing the rights of individuals against the need for police to quickly act during a fast-developing and inherently dangerous “hot pursuit.” The SJC explicitly stated that it was unreasonable to require police officers in pursuit of a suspect, and in continuous communication with each other over police radio broadcasts, to have to stop and confer with each other about the facts known to each other, even as the suspect continues to flee or to pose a danger.[xi] While the SJC did not explicitly limit application of the collective knowledge doctrine to fast-developing and potentially dangerous pursuits of suspects, the balancing test it employed and the frequency with which it discussed the needs of police in “hot pursuit” situations allow both the defense and prosecution room to argue the point. Defense counsel should consider whether the specific joint police operation in their case fits into the common but limited circumstances of the pursuit of suspects shortly after a crime. If the need for police flexibility or speed is reduced, or the pursuit does not involve dangerous circumstances, imputing knowledge of other team officers to an acting officer to justify the stop of a suspect may be unreasonable. On the other hand, prosecutors may argue that the collective knowledge doctrine applies to any investigation that leads to the seizure of a suspect or evidence because Privette did not make “hot pursuit” a requirement for invoking the doctrine and because the police continue to require flexibility even in more slowly developing investigations.

Following Privette, certain pieces of evidence will gain prominence in litigation over the application of the collective knowledge doctrine. For example, the SJC’s emphasis on the necessary “close and continuous communication” requirement in the context of police radio communications suggests that recordings of those radio communications, computer-aided dispatch (CAD) logs, and body-worn camera recordings will be essential evidence in cases where the Commonwealth invokes the collective knowledge doctrine to justify a warrantless stop or seizure. These recordings and logs will substantiate the degree of close communication between officers on a pursuit team and will identify which officers are part of the team. They also may reveal what facts were known to individual officers at the moment a suspect is apprehended, which of those facts were dispatched to the pursuit team, where those facts came from, and which critical facts were known to the acting officer at the time of the stop. If facts were not reported in radio transmissions or otherwise communicated between officers, or certain officers did not appear to be part of the pursuit team, the Commonwealth will have a difficult time arguing that the missing facts should be imputed to the acting officer.

In litigating the collective knowledge doctrine, particularly in suppression hearings where the Commonwealth bears the burden of producing evidence sufficient to establish reasonable suspicion or probable cause for a warrantless stop or seizure, the Commonwealth will need to collect and preserve any radio communications, recorded 911 calls, CAD logs, and body-worn camera recordings related to a pursuit. It will also need to ensure that these records are preserved in a manner that will allow them to be admissible at a suppression hearing. The Commonwealth should also collect any notes that officers may have kept during the pursuit, if those notes reflect the knowledge of an individual officer in a joint police pursuit, and especially if that information did not come from radio dispatches (for instance, from an on-scene witness). Conversely, defense counsel in their discovery motion practice should make broad and creative requests for any records related to the pursuit to be preserved and provided to the defense. If police relied on any other sources of information during the joint operation, such as surveillance videos of the relevant area, the Commonwealth and defense should act to preserve those materials. Counsel should not assume that these materials, especially private video recordings, are permanent: while police departments are modernizing their radio systems, not every department is able to save police radio and 911 recordings indefinitely, and other evidence—such as privately operated surveillance systems (including video doorbell cameras and store cameras)—is often erased or overwritten within days or weeks. If the Commonwealth negligently or recklessly fails to preserve evidence that is in the possession, custody, or control of the prosecution team, a motion judge may sanction the Commonwealth by refusing to consider that information when determining the aggregate information known to the investigative or pursuit team or may not credit police witnesses when deciding whether the Commonwealth has met its burden under Privette.

Finally, the Commonwealth will continue to bear the burden of establishing the reliability of any information it seeks to aggregate under the collective knowledge doctrine. Even if the acting officer reasonably relied upon information they learned through radio dispatches or from other officers or witnesses, that information will not support the legality of a stop if the Commonwealth does not establish its reliability. The traditional factors to determine the reliability of information continue to apply: the anonymity or identification of a witness providing information, the witness’s basis of knowledge of the information, the witness’s history of giving reliable information, corroborating information known to the officers, and the degree of specific details provided by the witness. Often, the admission into evidence of police radio recordings, such as the recording of an anonymous 911 caller, will be necessary to establish the reliability of information.[xii]

Clarification of the four requirements set forth in Privette must await further legal development. Because Privette borrows concepts from other jurisdictions’ application of the collective knowledge doctrine, reference to precedents in those jurisdictions will be important in defining the conditions where the doctrine should and should not apply. As the concurring opinions in Privette presage, these conditions may be difficult to ascertain in complicated circumstances. For example, will Privette continue to allow for unreasonable stops of individuals, as Justice Wendlandt opined, or will Privette unreasonably fetter the ability of police to safely and effectively protect the public during hot pursuits of suspects, as Justice Cypher fears?[xiii] What will be required to show “close and continuous communication?” What level of critical facts will the acting officer need to know to justify a stop? What officers may be included in the “joint investigative” team? In what circumstances may the horizontal collective knowledge doctrine even be applied: in any joint investigation or only in hot pursuit situations? Prosecutors and defendants will need to wrestle with the scope and operation of the new “fellow officer rule” as scenarios arise in the future.


[i] 491 Mass. 501 (2023).

[ii] Id. at 503. The horizontal collective knowledge doctrine is distinguished from the uncontroversial doctrine of vertical collective knowledge, in which the officer seizing a person (the “acting officer”) acts under the direction or request of another officer with the necessary knowledge to justify the stop or seizure (the “directing officer”). In vertical collective knowledge cases, the issue is whether the knowledge of the directing officer, and any information to be imputed to that officer because known to other officers in the team, is sufficient to establish legal cause to stop a suspect; the knowledge of the acting officer is irrelevant.

[iii] Commonwealth v. Roland R., 448 Mass. 278, 285 (2007) (citation omitted).

[iv] Privette, 491 Mass. at 510. A small number of jurisdictions have adopted an inevitable discovery exception to this rule, allowing non-communicated information to justify a stop or seizure if that information would have imminently become known to the acting officer. Id. at 511.

[v] Id. at 511-12.

[vi] In formulating these requirements, the SJC sometimes only referred to a reasonable suspicion analysis, not probable cause, but the SJC also discussed the collective knowledge doctrine in other jurisdictions for both reasonable suspicion and probable cause determinations. This formulation may be a recognition that, in the vast majority of circumstances invoking the application of the collective knowledge doctrine, including the underlying circumstances in Privette, the reviewing court will be considering a joint police operation shortly after a crime has occurred, in which the police are executing a dragnet and are likely to conduct a stop of a suspect on the basis of reasonable suspicion.

[vii] Privette, 491 Mass. at 513.

[viii] Id. at 515 (quoting United States v. Cook, 277 F.3d 82, 86 (1st Cir. 2002)).

[ix] Id. at 516.

[x] Id.

[xi] Id.

[xii] See Commonwealth v. Mubdi, 456 Mass. 385, 395-97 (2010); Commonwealth v. Depina, 456 Mass. 238, 243 (2010); Commonwealth v. Gomes, 75 Mass. App. Ct. 791, 794-95 (2009).

[xiii] Privette, 491 Mass. at 548-49 (Wendlandt, J., concurring); 491 Mass. at 541 (Cypher, J., concurring in part and dissenting in part). The SJC was unanimous that, whatever legal analysis applied, the police had a reasonable basis to stop and frisk Mr. Privette.


John Hayes is currently a supervising senior trial counsel in the Boston Trial Unit of the Committee for Public Counsel Services. He previously was attorney in charge of the Boston Superior Court Trial Unit and has been a trial attorney with CPCS since he received his JD from Boston College Law School in 1990. Mr. Hayes just completed a three-year term with the Council of the Boston Bar Association, was also a member of the Executive Committee, and is currently a member of the Amicus Committee and Criminal Law Section.

The defendant in Privette is a client of an attorney with CPCS, and the appeal leading to the decision in Commonwealth v. Privette was also handled by a CPCS attorney, but Mr. Hayes was not involved in the representation of Mr. Privette either before the Superior Court or the Supreme Judicial Court.

This article represents the opinions and legal conclusions of its author and not necessarily those of the Committee for Public Counsel Services.