Case Title: Commonwealth v. Privette

Citation: 

Docket Number: SJC-13248

State: massachusetts

Court: Massachusetts Supreme Court

Date: 2023-03-28T00:00:00Z

Document:
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SJC-13248 
 
COMMONWEALTH  vs.  DAVID PRIVETTE. 
 
 
 
Suffolk.     September 9, 2022. - March 28, 2023. 
 
Present:  Budd, C.J., Gaziano, Lowy, Cypher, Kafker, Wendlandt, 
& Georges, JJ. 
 
 
Firearms.  Practice, Criminal, Motion to suppress, Interlocutory 
appeal.  Evidence, State of police knowledge.  
Constitutional Law, Search and seizure, Reasonable 
suspicion, Investigatory stop.  Search and Seizure, 
Reasonable suspicion, Threshold police inquiry.  Threshold 
Police Inquiry. 
 
 
 
 
Indictments found and returned in the Superior Court 
Department on October 10, 2018. 
 
 
A pretrial motion to suppress evidence was heard by Elaine 
M. Buckley, J. 
 
An application for leave to prosecute an interlocutory 
appeal was allowed by Lenk, J., in the Supreme Judicial Court 
for the county of Suffolk, and the appeal was reported by her to 
the Appeals Court.  After review by the Appeals Court, the 
Supreme Judicial Court granted leave to obtain further appellate 
review. 
 
 
Anne Rousseve, Committee for Public Counsel Services, for 
the defendant. 
Kathryn Sherman, Assistant District Attorney, for the 
Commonwealth. 
2 
 
 
 
 
GAZIANO, J.  On a rainy, early morning in August of 2018, 
Boston police officers received a report of an armed robbery of 
a gasoline station in the Clam Point area of the Dorchester 
section of Boston at 3:35 A.M.  The first radio report described 
the suspect as a "Black male, late twenties, five foot seven, 
blue hoodie, blue jeans, on foot towards [a pharmacy]."  Later 
dispatches added that the suspect had facial hair.  Seven 
minutes after the first dispatch, and one street away from the 
location of the armed robbery, an officer stopped the defendant.  
Contemporaneously, other officers responding to the call were 
canvassing the area for potential suspects; one of the officers 
continued to communicate via the police department radio channel 
dedicated to use in the area.  This officer arrived at the 
location of the investigatory stop at the same time as the 
officer who initiated the stop.  After a patfrisk of the 
defendant's person and his backpack by both officers revealed 
$432 and a firearm, the defendant was arrested and indicted for 
multiple firearms offenses.  He filed a motion to suppress the 
items seized as a result of the stop, on the ground that the 
officer who initiated it lacked the requisite reasonable 
suspicion.  After an evidentiary hearing, a Superior Court judge 
denied the motion, and the defendant sought interlocutory 
review.  The single justice allowed the appeal to proceed in the 
3 
 
Appeals Court, where the court affirmed the denial of the motion 
to suppress.  We then allowed the defendant's application for 
further appellate review. 
 
We are tasked with deciding whether, through the collective 
knowledge doctrine, information known to other investigating 
officers may be imputed to the officer who initiated the stop, 
and thus be included in the calculus of reasonable suspicion 
without violating art. 14 of the Massachusetts Declaration of 
Rights.  To date, we have permitted the aggregation of 
information known to one police officer to other officers for 
consideration in the calculus of reasonable suspicion or 
probable cause, even without evidence of communication among the 
officers, so long as they were engaged in a cooperative effort.  
See, e.g., Commonwealth v. Mendez, 476 Mass. 512, 519 n.8 (2017) 
(trooper's knowledge that defendant was suspect in shooting was 
imputed to other arresting officer, even absent evidence of 
direct communication between officers), citing Commonwealth v. 
Quinn, 68 Mass. App. Ct. 476, 480-481 (2007), quoting 
Commonwealth v. Riggins, 366 Mass. 81, 88 (1974) ("Where a 
cooperative effort is involved, facts within the knowledge of 
one police officer have been relied on to justify the conduct of 
another"); Commonwealth v. Montoya, 464 Mass. 566, 576 (2013) 
(imputing one officer's knowledge that individual just purchased 
drugs to acting officer absent communication); Commonwealth v. 
4 
 
Roland R., 448 Mass. 278, 285 (2007) ("the knowledge of each 
officer is treated as the common knowledge of all officers" 
[citation omitted]). 
 
We conclude that, with respect to the horizontal collective 
knowledge doctrine, art. 14 requires more.  To be consistent 
with the requirements of art. 14, in order to aggregate 
officers' knowledge, the officers must be involved in a joint 
investigation, pursuing a mutual purpose and objective, and they 
must be in close and continuous communication with each other 
about that shared objective.  While the officer who actually 
effectuates the stop need not have personal knowledge of all of 
the officers' pooled knowledge giving rise to reasonable 
suspicion or probable cause, the officer must be aware of at 
least some of the critical facts and must have been in 
communication with others who have such knowledge. 
 
In the circumstances here, some, but not all, of the other 
investigating officers' knowledge can be imputed to the acting 
officer.  We conclude that, with or without this imputed 
knowledge, the officer who stopped the defendant had reasonable 
suspicion to do so. 
 
1.  Background.  a.  Facts.  We summarize the relevant 
facts concerning the stop from the motion judge's findings, 
supplemented by uncontroverted and undisputed facts from the 
record that have been credited by the motion judge, leaving 
5 
 
certain details for later discussion.  See Commonwealth v. 
Jones-Pannell, 472 Mass. 429, 431 (2015).  Three Boston police 
officers testified at the evidentiary hearing on the motion to 
suppress:  Officer Brian Doherty, Lieutenant Darrell Dwan,1 and 
Officer Luis Lopez.  The motion judge found each testifying 
officer credible without qualification. 
 
On August 12, 2018, Doherty, who was assigned to the police 
department's C-11 district, was working the midnight shift and 
covering the Clam Point area of Dorchester.  He was in plain 
clothes and driving an unmarked vehicle.  At approximately 
3:35 A.M., Doherty received a police department radio 
transmission over channel six2 reporting that there had been an 
armed robbery at a gasoline station on Morrissey Boulevard.  The 
dispatcher thereafter transmitted a description of the suspect 
as "Black male, late twenties, five foot seven, blue hoodie, 
blue jeans, on foot towards [a pharmacy]."  In the first 
dispatch, there was no mention of the suspect having facial 
hair. 
 
Officers continued to communicate via channel six.  Dwan, 
who was canvassing the surrounding streets, reported at 
 
 
1 At the time of the robbery, Dwan held the rank of 
sergeant. 
 
 
2 Channel six is the dedicated police channel for the C-11 
area and is transmitted to the entire district. 
6 
 
3:37 A.M. that no one was present on his part of Morrissey 
Boulevard.3  Over the course of the next seven minutes, the 
dispatcher transmitted two additional descriptions of the 
suspect over channel six.  A second transmission was broadcast 
at 3:38 A.M. and described the suspect as being "a Black male, 
twenty-eight, twenty-nine, medium build, five foot seven, five 
foot eight, blue hoodie, blue jeans, with facial hair, silver 
firearm."  The final description was dispatched at 3:41 A.M., 
and described the suspect as a "Black male, twenty-eight, 
twenty-nine, medium build, five foot seven, five foot eight, 
blue hoodie, blue jeans, some facial hair."4 
 
In response to the dispatched report of the armed robbery, 
Doherty headed toward the area near the pharmacy from the police 
station where he had been working.  At that time, Doherty had 
been a Boston police officer for four years and had been working 
in Clam Point for two years.  He also had grown up a few blocks 
away from the scene of the robbery.  Doherty was aware of a 
large gap in a fence that separated Morrissey Boulevard and 
Ashland Street not far from the scene.  As he was responding to 
the dispatch, Doherty drove through approximately nine streets 
 
 
3 Dwan confirmed via channel six that no one was present on 
Morrissey Boulevard.  The recordings of the dispatches, which 
were introduced in evidence, support this testimony. 
 
 
4 Dwan testified that he heard updated descriptions of the 
suspect and that he knew the suspect had facial hair. 
7 
 
without seeing anyone else outside; he was monitoring channel 
six while driving.  Seven minutes after the robbery, Doherty 
came across the defendant on Ashland Street. 
 
When Doherty saw the defendant at 3:41 A.M., it was raining 
and dark.  Doherty observed that the individual walking toward 
him was a Black male with facial hair, wearing a green sweater 
and black jeans, and of the same approximate age as the 
broadcast description.  At the time of the encounter, the 
defendant was five feet, eleven inches tall and thirty-two years 
old.  Doherty pulled over and parked, identified himself as 
"Boston Police," and told the defendant to "show me your hands."  
The defendant complied; he made no attempt to run or to evade 
the officer.  Doherty then conducted a patfrisk of the defendant 
and felt a large wad in the defendant's pocket.  Doherty 
instructed the defendant to remove what was in his pocket, which 
turned out to be $432.  No weapons were recovered from the 
defendant's person. 
 
Dwan arrived at the corner of Ashland Street and Everdean 
Street, from the opposite direction, at the same time that 
Doherty reached that location.  As Dwan approached the defendant 
from behind, he saw that the defendant was wearing a red plaid 
backpack.  Dwan pat frisked the backpack, without opening it, 
and felt a hard object near the top.  Upon opening the backpack, 
Dwan saw a silver gun. 
8 
 
 
Lopez also was on duty on the night of the robbery.  In 
response to the communications on channel six, Lopez drove 
around the surrounding Clam Point neighborhood, focusing his 
efforts on Victory Road and the area near the pharmacy.  Nothing 
in the record indicates that Lopez communicated with anyone 
during his surveillance, nor that he was involved in the stop of 
the defendant.  After observing no one in the area, Lopez 
transported the victim to the scene of the stop for a showup 
identification.  Following a positive identification by the 
victim, the defendant was arrested. 
 
b.  Procedural background.  On October 10, 2018, a grand 
jury returned indictments charging the defendant with five 
firearms offenses.5  He filed a motion to suppress the evidence 
obtained as a result of the stop, the patfrisk of his person, 
and the patfrisk of his backpack.  He also moved to suppress the 
subsequent showup identification.  Following an evidentiary 
hearing, a Superior Court judge denied the defendant's motion. 
 
In her findings, the motion judge reasoned that Doherty had 
had adequate reasonable suspicion to conduct the investigatory 
stop based on the defendant's presence "in the locus of the 
 
 
5 The charges included armed robbery, G. L. c. 265, § 17; 
possession of a firearm during the commission of a felony, G. L. 
c. 265, § 18B; possession of a firearm as an armed career 
criminal, G. L. c. 269, §§ 10 (a), 10G (b); possession of 
ammunition without a firearm identification card, G. L. c. 269, 
§ 10 (h); and carrying a loaded firearm, G. L. c. 269, § 10 (n). 
9 
 
robbery and within minutes of its occurrence."  She also 
considered the early morning hour, the fact that the defendant 
was the only person observed in the area, and the fact that he 
fit the general description that was broadcast on channel six. 
 
The defendant filed an application for leave to pursue an 
interlocutory appeal in the county court pursuant to Mass. R. 
Crim. P. 15 (a) (2), as amended, 476 Mass. 1501 (2017).  The 
single justice allowed the application and ordered the appeal to 
proceed in the Appeals Court.  The Appeals Court affirmed the 
denial of the motion to suppress.  See Commonwealth v. Privette, 
100 Mass. App. Ct. 222, 222-223 (2021).  In its calculus of 
reasonable suspicion, the Appeals Court supplemented the motion 
judge's findings by imputing to Doherty Dwan's knowledge that 
the suspect had a beard and that Dwan saw no one walking in the 
area of Morrissey Boulevard or Victory Road.  Id. at 228.  The 
Appeals Court also imputed to Doherty Lopez's knowledge that no 
one had been present in the area of Victory Road.  Id.  In 
affirming the denial of the motion to suppress, the Appeals 
Court held that the defendant's appearance, his proximity to the 
scene, and the fact that he was the only person outside in the 
surrounding area all supported a determination that there was 
reasonable suspicion.  Id. at 231-233.  We granted the 
defendant's application for further appellate review. 
10 
 
 
2.  Discussion.  On appeal, the defendant challenges only 
the validity of the stop.  He does not challenge the patfrisk of 
his person or his backpack, nor does he challenge the 
identification procedure.  Thus, the narrow question before us 
is whether the investigatory stop was constitutionally 
permissible. 
 
a.  Standard of review.  In reviewing a ruling on a motion 
to suppress, we accept the motion judge's findings of fact 
absent clear error.  Commonwealth v. Tremblay, 480 Mass. 645, 
652 (2018).  We conduct an independent review of the judge's 
application of constitutional principles to the facts found.  
Commonwealth v. Mercado, 422 Mass. 367, 369 (1996). 
 
b.  Reasonable suspicion.  Article 14 provides that 
"[e]very subject has a right to be secure from all unreasonable 
searches, and seizures, of his person."  To justify an 
investigatory stop under art. 14, a police officer must have 
reasonable suspicion that the person stopped has committed, is 
committing, or is about to commit a crime.  Commonwealth v. 
Costa, 448 Mass. 510, 514 (2007).  The reasonable suspicion 
analysis examines "the totality of the facts on which the 
seizure is based."  Commonwealth v. Meneus, 476 Mass. 231, 235 
(2017).  Reasonable suspicion "must be based on specific and 
articulable facts, and reasonable inferences therefrom, in light 
of the officer's experience" (citation omitted).  Commonwealth 
11 
 
v. Gomes, 453 Mass. 506, 511 (2009).  See Terry v. Ohio, 392 
U.S. 1, 21 (1968).  Reasonable suspicion also must be more than 
a hunch.  Commonwealth v. Lyons, 409 Mass. 16, 19 (1990). 
 
As an initial matter, the motion judge found, and the 
parties agree, that the defendant was seized when Doherty 
announced to him, "Boston Police," and told him to "show me your 
hands."  The question before us is whether Doherty had 
reasonable suspicion to justify the stop.  This, in turn, 
implicates the narrow legal issue whether Dwan's and Lopez's 
knowledge and observations that night may be imputed to Doherty, 
under the collective knowledge doctrine. 
 
i.  Collective knowledge doctrine.  The collective 
knowledge doctrine, sometimes referred to as the fellow officer 
rule, originated in Williams v. United States, 308 F.2d 326, 327 
(D.C. Cir. 1962), where the United States Court of Appeals for 
the District of Columbia Circuit rejected a defendant's 
assertion that the arresting officer was required to have had 
firsthand information in order to make an arrest.  The court 
concluded that "the collective knowledge of the organization as 
a whole can be imputed to an individual officer when he is 
requested or authorized by superiors or associates to make an 
arrest."  Id.  The United States Supreme Court subsequently 
adopted the doctrine.  See Whiteley v. Warden, Wyo. State 
Penitentiary, 401 U.S. 560, 568 (1971).  The Court initially 
12 
 
concluded that "[c]ertainly police officers called upon to aid 
other officers in executing arrest warrants are entitled to 
assume that the officers requesting aid offered the magistrate 
the information requisite to support an independent judicial 
assessment of probable cause."  See id.  The Court later held 
that, in forming reasonable suspicion for an investigatory stop, 
officers could rely on a police bulletin issued by another 
police department, even though the acting officers were not 
"themselves aware of the specific facts which led their 
colleagues to seek their assistance."  See United States v. 
Hensley, 469 U.S. 221, 231 (1985). 
 
More recently, the collective knowledge doctrine has 
evolved into two different types:  horizontal collective 
knowledge and vertical collective knowledge.  Each is used in 
determining the existence of reasonable suspicion and probable 
cause.  See United States v. Massenburg, 654 F.3d 480, 495-496 
(4th Cir. 2011) (distinguishing between horizontal and vertical 
collective knowledge and analyzing collective knowledge doctrine 
as it applies to reasonable suspicion); United States v. Chavez, 
534 F.3d 1338, 1345 (10th Cir. 2008), cert. denied, 555 U.S. 
1121 (2009) (analyzing probable cause based on collective 
knowledge). 
 
Vertical collective knowledge, the original version of the 
doctrine, involves one officer directing or requesting another 
13 
 
officer to conduct a stop, frisk, search, or an arrest.  Courts 
review the validity of the intrusion based on the directing 
officer's knowledge.  See Massenburg, 654 F.3d at 493 ("the 
collective-knowledge doctrine simply directs us to substitute 
the knowledge of the instructing officer or officers for the 
knowledge of the acting officer").  In this context, it is not 
necessary for the acting officers to have personal knowledge of 
the facts establishing reasonable suspicion or probable cause, 
because the acting officers "are acting as the agents or proxies 
of, or are relying on information provided by, the officers who 
possess probable cause or reasonable suspicion."  United States 
v. Gorham, 317 F. Supp. 3d 459, 473 (D.D.C. 2018). 
 
The horizontal knowledge doctrine, by contrast, permits the 
aggregation of information known to multiple officers; no one 
officer need have sufficient information to support probable 
cause or reasonable suspicion.  Instead, "a number of individual 
law enforcement officers have pieces of the probable cause 
puzzle" that are aggregated to meet the threshold.  See Chavez, 
534 F.3d at 1345.  Under the horizontal collective knowledge 
doctrine, officers are not acting at the direction of another, 
as they would be under the vertical collective knowledge 
doctrine.  See Commonwealth v. Yong, 644 Pa. 613, 636, cert. 
denied, 139 S. Ct. 374 (2018) (doctrine of horizontal collective 
14 
 
knowledge is one in which "the arresting officer does not have 
the requisite knowledge and was not directed to so act"). 
 
Reliance upon vertical collective knowledge has sparked 
little controversy and is supported by the United States Supreme 
Court's decision in Hensley, 469 U.S. at 231 ("this rule is a 
matter of common sense").  By contrast, both Federal and State 
courts are split over how broadly to apply the horizontal 
outgrowth of the collective knowledge doctrine, the question at 
issue here.  Moreover, further complicating the issue, 
notwithstanding the evolution of the doctrine into these two 
distinct approaches, not all fact patterns will necessarily fall 
squarely within either the vertical or horizontal framework.  
See Yong, 644 Pa. at 636, citing Chavez, 534 F.3d at 1345 n.12. 
 
At this point, those courts to have addressed the question 
of horizontal collective knowledge have required communication 
between officers prior to an intrusion, a joint cooperative 
effort, close physical proximity, or some combination thereof.  
See, e.g., Grassi v. People, 2014 CO 12, ¶ 1, cert. denied, 574 
U.S. 1014 (allowing imputation of collective knowledge to 
officer only if "(1) that officer acts pursuant to a coordinated 
investigation and (2) the police possess the information at the 
time of the search or arrest").  To date, courts have developed 
at least three variations of the horizontal collective knowledge 
doctrine. 
15 
 
 
The United States Courts of Appeals for the Second, Fourth, 
and Tenth Circuits, and a plurality of the States6 to have 
addressed the issue, have required evidence that the actual 
facts underlying the analysis of reasonable suspicion or 
probable cause be communicated to the acting officer prior to 
the stop, frisk, search, or arrest.  See, e.g., United States v. 
Hussain, 835 F.3d 307, 316 n.8 (2d Cir. 2016). 
 
The United States Court of Appeals for the Fourth Circuit 
discussed this approach in some detail in Massenburg, 654 F.3d 
at 491-496.  The court noted concerns about the effect that 
after-the-fact aggregation of information would have on the 
exclusionary rule.  "Because it jettisons the present 
requirement of communication between an instructing and an 
acting officer, officers would have no way of knowing before a 
 
 
6 See People v. Chalak, 48 Cal. App. 5th Supp. 14, 20 
(2020); State v. Cooley, 457 A.2d 352, 353 (Del. 1983); Montes-
Valeton v. State, 216 So. 3d 475, 479 (Fla. 2017); State v. 
Fischer, 230 Ga. App. 613, 614 (1998), overruled on other 
grounds by Workman v. State, 235 Ga. App. 800, 803 (1998); State 
v. Barnes, 58 Haw. 333, 336-337 (1977); State v. Amstutz, 169 
Idaho 144, 148 (2021); People v. Creach, 69 Ill. App. 3d 874, 
882 (1979); State v. M.J.M., 837 N.E.2d 223, 226 (Ind. Ct. App. 
2005); State v. Miller, 49 Kan. App. 2d 491, 497 (2013); State 
vs. Giannini, N.M. Ct. App., No. 34,199, slip op. at 5 (July 20, 
2016); State v. Battle, 109 N.C. App. 367, 371 (1993); State v. 
Rahier, 2014 ND 153, ¶ 15; State v. Ojezua, 2016-Ohio-2659, ¶¶ 
38-40 (App. Ct.); State v. Mickelson, 18 Or. App. 647, 650 
(1974); State v. Mohr, 2013 S.D. 94, ¶ 18; State v. Echols, 382 
S.W.3d 266, 278 (Tenn. 2012); McArthur v. Commonwealth, 72 Va. 
App. 352, 365 (2020); Guandong v. State,  2022 WY 83, ¶¶ 19-20. 
16 
 
search or seizure whether the aggregation rule would make it 
legal, or even how likely that is."  Id. at 494.  Jurisdictions 
adopting this approach have explained that the deterrent effect 
of the exclusionary rule would be greatly limited without a 
requirement of communication; the absence of such a requirement 
could create incentives for officers to conduct illegal searches 
and seizures, knowing that there was no reasonable suspicion or 
probable cause, on the slim chance that someone else on the team 
had had the requisite information.  See id. ("Perhaps an officer 
who knows she lacks cause for a search will be more likely to 
roll the dice and conduct the search anyway, in the hopes that 
uncommunicated information existed").  See McArthur v. 
Commonwealth, 72 Va. App. 352, 365 (2020) (citing similar 
concerns that "the legality of a warrantless search would depend 
solely on whether officers [were] able to gather information 
held by other officers, after-the-fact, to create reasonable 
suspicion or probable cause"). 
 
Another concern that has been mentioned with the 
aggregation of uncommunicated information is that it could 
reward police officers who were acting in bad faith; for 
example, investigatory teams invariably could find sufficient 
probable cause or reasonable suspicion based on information that 
had been learned after the stop.  See Gorham, 317 F. Supp. 3d 
at 473, citing Massenburg, 654 F.3d at 494.  For these reasons, 
17 
 
jurisdictions that limit the horizontal collective knowledge 
doctrine require communication of the pertinent information 
prior to permitting it to be factored into the calculus of 
reasonable suspicion or probable cause.  See, e.g., Chavez, 534 
F.3d at 1345, citing United States v. Shareef, 100 F.3d 1491, 
1504 (10th Cir. 1996) ("In such situations, the court must 
consider whether the individual officers have communicated the 
information they possess individually, thereby pooling their 
collective knowledge to meet the probable cause threshold"); 
State v. M.J.M., 837 N.E.2d 223, 226 (Ind. Ct. App. 2005) ("In 
order to rely on collective knowledge, the knowledge sufficient 
for reasonable suspicion must be conveyed to the investigating 
officer before the stop is made"). 
 
Following a decision by the United States Court of Appeals 
for the Fifth Circuit, see United States v. Ragsdale, 470 F.2d 
24, 30 (5th Cir. 1972), a small number of jurisdictions have 
adopted an exception to the requirement that the acting officer 
act with awareness of the other officers' knowledge, sometimes 
known as the inevitable discovery exception, see 2 W.R. LaFave, 
Search & Seizure § 3.5(c), at 351-352 (6th ed. 2020).  See, 
e.g., Hurlburt v. State, 425 P.3d 189, 194-195 (Alaska Ct. App. 
2018) (adopting inevitability exception in analysis of 
reasonable suspicion in case involving driving under influence); 
State v. Ochoa, 131 Ariz. 175, 178 (Ariz. Ct. App. 1981) 
18 
 
(declining to hold intrusion was unconstitutional "simply 
because a member of the team having less knowledge than the 
others moved too quickly and did what the more knowledgeable 
members of the team would imminently and lawfully have done"); 
Smith v. State, 719 So. 2d 1018, 1023 (Fla. Dist. Ct. App. 1998) 
("when the officer who does possess the probable cause is in a 
close time-space proximity, evidence of a direct communications 
link between the officers is not necessarily required"); Yong, 
644 Pa. at 636 ("we hold the seizure is still constitutional 
where the investigating officer with probable cause or 
reasonable suspicion was working with the officer and would have 
inevitably and imminently ordered that the seizure be 
effectuated"). 
 
The second approach to the horizontal collective knowledge 
doctrine requires communication amongst officers to establish 
that they are engaged in a joint effort, even though explicit 
communication of the underlying facts supporting reasonable 
suspicion or probable cause is not necessary.  To date, a 
plurality of United States Courts of Appeals, and a handful of 
States, have permitted aggregation, so long as there is evidence 
of some communication between the officers involved in the 
investigation; relaying the specific facts that provided the 
basis for reasonable suspicion or probable cause generally has 
not been required.  See United States v. Ramirez, 473 F.3d 1026, 
19 
 
1032, 1037 (9th Cir. 2007).  See, e.g., State v. Breeding, 200 
So. 3d 1193, 1200 (Ala. Crim. App. 2015), quoting United States 
v. Esle, 743 F.2d 1465, 1476 (11th Cir. 1984), overruled on 
other grounds by United States v. Blankenship, 382 F.3d 1110, 
1122 n.23 (11th Cir. 2004) ("[I]t is a 'well-recognized 
principle that, where a group of officers is conducting an 
operation and there is at least minimal communication among 
them, [the appropriate course is to] look to the collective 
knowledge of the officers in determining probable cause'"). 
 
For instance, the United States Court of Appeals for the 
Fifth Circuit has held that "probable cause can rest upon the 
collective knowledge of the police, rather than solely on that 
of the officer who actually makes the arrest, when there is some 
degree of communication between" those officers (quotations and 
citation omitted).  United States v. Kye Soo Lee, 962 F.2d 430, 
435 (5th Cir. 1992), cert. denied, 506 U.S. 1083 (1993).  See 
United States v. Ibarra, 493 F.3d 526, 530 (5th Cir. 2007) 
("Under the collective knowledge doctrine, it is not necessary 
for the arresting officer to know all of the facts amounting to 
probable cause, as long as there is some degree of communication 
between the arresting officer and an officer who has knowledge 
of all the necessary facts").  The United States Court of 
Appeals for the Sixth Circuit permits the knowledge of a group 
of officers to "be considered in determining probable cause, not 
20 
 
just the knowledge of the individual who physically effected the 
arrest," so long as the "agents [were] in close communication 
with one another."  United States v. Blair, 524 F.3d 740, 752 
(6th Cir. 2008), quoting United States v. Woods, 544 F.2d 242, 
260 (6th Cir. 1976).  Otherwise put, the requirement of 
communication "serves to distinguish between officers 
functioning as a 'search team,' and officers acting as 
independent actors who merely happen to be investigating the 
same subject" (citation omitted).  United States v. Gillette, 
245 F.3d 1032, 1034 (8th Cir.), cert. denied, 534 U.S. 982 
(2001). 
 
Finally, the minority view, which has been adopted by the 
United States Courts of Appeals for the First and Third 
Circuits, and a handful of States (including, to date, 
Massachusetts), has allowed information to be aggregated amongst 
officers even absent evidence of any sort of communication 
between them.  See, e.g., United States v. Cruz-Rivera, 14 F.4th 
32, 44 (1st Cir. 2021), cert. denied, 142 S. Ct. 1456 (2022), 
quoting United States v. Azor, 881 F.3d 1, 8 (1st Cir. 2017) 
("we 'look to the collective information known to the law 
enforcement officers participating in the investigation rather 
than isolat[ing] the information known by the individual 
arresting officer'"); United States v. Whitfield, 634 F.3d 741, 
746 (3d Cir. 2010) ("it would be impractical to expect an 
21 
 
officer in such a situation to communicate to the other officers 
every fact that could be pertinent in a subsequent reasonable 
suspicion analysis"); State v. Goff, 129 S.W.3d 857, 863 (Mo. 
2004) (declining to require specific communication between 
officers in order to aggregate information in making 
determination of reasonable suspicion or probable cause).  See 
also Mendez, 476 Mass. at 519 n.8 (imputing uncommunicated 
knowledge from one officer to another in calculus of reasonable 
suspicion).  These jurisdictions reason that no communication is 
required because the officers are working together on the same 
investigation; the officers thus have a "nexus to the 
investigation," Goff, supra, are "involved in the [same] 
investigation," United States v. Fiasconaro, 315 F.3d 28, 36 
(1st Cir. 2002), or are acting as a "single organism," Shareef, 
100 F.3d at 1504 n.6. 
 
ii.  Horizontal collective knowledge doctrine under 
art. 14.  The defendant urges us to reject all forms of the 
horizontal collective knowledge doctrine; he argues that the 
doctrine of horizontal collective knowledge undermines the 
deterrent effect of the exclusionary rule and is offensive to 
the requirements of art. 14.  The Commonwealth argues that we 
need not reach the issue here, because Doherty had reasonable 
suspicion without imputing the knowledge of Dwan and Lopez to 
him. 
22 
 
 
We conclude that, to comport with art. 14, application of 
the horizontal collective knowledge doctrine must be limited, 
but not so much so that it disregards the practical reality of 
effective law enforcement.  See Beck v. Ohio, 379 U.S. 89, 91 
(1964) ("The rule of probable cause is a practical, nontechnical 
conception affording the best compromise that has been found for 
accommodating . . . often opposing interests.  Requiring more 
would unduly hamper law enforcement.  To allow less would be to 
leave law-abiding citizens at the mercy of the officers' whim or 
caprice" [citation omitted]). 
 
Where there is no directive or instruction from a superior 
officer, in order to aggregate officers' knowledge for use in 
the determination of reasonable suspicion without running afoul 
of art. 14, the officers must be involved in a joint 
investigation, with a mutual purpose and objective, and must be 
in close and continuous communication with each other about that 
objective.  See, e.g., United States v. Sandoval-Venegas, 292 
F.3d 1101, 1105 (9th Cir. 2002).  While the acting officer need 
not have knowledge of all of the facts giving rise to reasonable 
suspicion or probable cause, the officer must have knowledge of 
at least some of the critical facts.  See, e.g., United States 
v. Bernard, 623 F.2d 551, 560-561 (9th Cir. 1979). 
 
In order for their knowledge to be pooled such that "[i]n 
effect all of them participated in the decision to make the 
23 
 
arrests," Bernard, 623 F.2d at 560, the officers must be 
actively involved in the same investigation, with a shared and 
mutual objective.  See United States v. Nafzger, 974 F.2d 906, 
914 (7th Cir. 1992) (all officers "were part of a coordinated 
investigation" of defendant who was suspected of being involved 
in organized crime ring).  The officers must be "functioning as 
a team," as opposed to working as "independent actors who merely 
happen to be investigating the same subject" (citation omitted).  
See Ramirez, 473 F.3d at 1033; Gillette, 245 F.3d at 1034. 
 
"'Working as a team' is also conceptualized as agents 
working 'in close communication with one another.'"  United 
States v. Duval, 742 F.3d 246, 253 (6th Cir.), cert. denied, 574 
U.S. 823 (2014), quoting Woods, 544 F.2d at 260.  See, e.g., 
Sandoval-Venegas, 292 F.3d at 1105-1106 (detectives 
investigating bank robbery "were in continuous collective 
contact" during pursuit of robber, and one of detectives at 
scene of arrest knew of facts establishing probable cause and 
was standing at elbow of officer who made arrest, such that 
arresting officer need not be viewed as "an island," but, 
rather, "their pooled knowledge" could be considered to support 
probable cause for apprehension of suspected robber).  "The 
inquiry in such a circumstance is 'whether the individual 
officers have communicated the information they possess 
individually, thereby pooling their collective knowledge' to 
24 
 
satisfy the relevant standard."  United States v. Whitley, 680 
F.3d 1227, 1234 n.3 (10th Cir. 2012), quoting Chavez, 534 F.3d 
at 1345. 
 
For officers in a joint investigation to be considered in 
close communication, they must be continuously conferring with 
each other throughout the course of the investigation, 
exchanging information to the extent possible.  See State v. 
Barnes, 58 Haw. 333, 336 (1977), and cases cited ("While police 
officers are acting in concert and are keeping each other 
informed of the progress of a particular investigation, the 
knowledge of each is deemed to be the knowledge of all"). 
 
"Basing the legitimacy of the stop solely on what the 
officer who first approaches the suspect knows" rather than on 
the collective knowledge of the officers involved and 
communicating throughout the stop "makes little sense from a 
practical standpoint."  See United States v. Cook, 277 F.3d 82, 
86 (1st Cir. 2002).  At the same time, the doctrine of 
horizontal collective knowledge "does not allow officers to make 
arrests without probable cause simply because some other 
officer, somewhere, has probable cause to arrest."  See Ochoa, 
131 Ariz. at 177.  Although all the information giving rise to 
reasonable suspicion or probable cause need not be explicitly 
communicated to the acting officer, some of the "critical 
information" supporting the constitutional justification must be 
25 
 
shared with, or otherwise known to, that officer, and the 
exchange of information among the group of officers must be such 
that "the knowledge of one of them [is] the knowledge of all" 
(citation omitted).  Bernard, 623 F.2d at 561. 
 
This approach duly balances the right of individuals to be 
free from unreasonable searches and seizures with the practical 
needs of officers jointly conducting investigations that are 
unfolding from moment to moment.  See Commonwealth v. Feliz, 486 
Mass. 510, 515 (2020), quoting Commonwealth v. Catanzaro, 441 
Mass. 46, 56 (2004) ("There is no ready test for reasonableness 
except by balancing the need to search or seize against the 
invasion that the search or seizure entails").  See also Cook, 
277 F.3d at 86 ("common sense and practical considerations must 
guide judgments about the reasonableness of searches and 
seizures").  It provides flexibility in "dynamic environment[s] 
marked by the potential for violence," where officers may have 
no opportunity to communicate each piece of relevant information 
during the course of the stop, see id., while nonetheless 
necessitating general communication amongst officers in order 
for a stop to pass constitutional muster. 
 
The approach suggested by Justice Cypher, by contrast, 
would allow post hoc rationalizations by scouring all of the 
information any number of officers had gathered on a particular 
subject, over an unlimited time frame and in any location, to 
26 
 
cobble together a justification for the stop.  Indeed, in her 
view, the officer making the stop would not have to have 
knowledge of any of the facts establishing reasonable suspicion 
to conduct the stop, nor would any other individual officer. 
 
The approach suggested by Justice Wendlandt, on the other 
hand, would require officers who have been in hot pursuit of a 
fleeing suspect, communicating over police radio broadcasts, to 
stop and confer with each other about the facts known to each of 
them before deciding whether they had sufficient information to 
stop the suspect, who would be unlikely to stand and wait for 
this conference to end before continuing to flee.  We discern no 
reason why police using electronic communication while in 
pursuit should be held to this heightened standard.  See 
Hensley, 469 U.S. at 231, quoting United States v. Robinson, 536 
F.2d 1298, 1300 (9th Cir. 1976) ("effective law enforcement 
cannot be conducted unless police officers can act on directions 
and information transmitted by one officer to another and . . . 
officers, who must often act swiftly, cannot be expected to 
cross-examine their fellow officers about the foundation for the 
transmitted information").  Where each officer has communicated 
his or her knowledge to the others during the course of the 
pursuit, this shared knowledge is sufficient to establish 
reasonable suspicion, and the officer conducting the stop is 
27 
 
aware of some of the critical elements, the requirements of 
art. 14 are satisfied. 
 
Contrary to Justice Wendlandt's assertions, our approach 
would not permit an officer on patrol to stop an individual at 
random and then attempt to create a post hoc justification based 
on other officers' knowledge from some previous investigation.  
The officers all must be involved in a joint, ongoing 
investigation, and in close communication as they pursue the 
suspect.  Although Justice Wendlandt views the stop here as 
"rest[ing] on the hope that, post hoc, a judge will cobble 
together information known to other officers on the team" about 
which the acting officer is "entirely ignorant and has no basis 
to believe is known to a fellow officer," post at    , in 
actuality, the officer who had heard the information about the 
suspect having a beard was standing at the elbow of the officer 
who initiated the stop, just as Justice Wendlandt states would 
be acceptable under the inevitable discovery exception to the 
exclusionary rule.  See post at    .  Use of the inevitable 
discovery exception would not, however, address all 
circumstances that officers might encounter in the course of a 
developing, real-time pursuit.  Here, for instance, had Dwan 
turned onto another road perpendicular to Morrissey Boulevard 
and within blocks of the scene of the crime, he would have been 
heading in a completely different direction from the location of 
28 
 
the stop, and yet still in the reported path of flight; and he 
might not have encountered the defendant before he was able to 
reach nearby commercial areas from which the defendant might 
have been able to perfect an escape. 
 
The approach we adopt balances 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.  See Terry, 392 U.S. at 27.  
As Justice Wendlandt asserts, post at    , quoting Terry, supra 
at 10, Terry's "strictly circumscribed permission was designed 
to give the officer on the scene 'an escalating set of flexible 
responses, graduated in relation to the amount of information' 
possessed by the officer, during the 'rapidly unfolding and 
often dangerous situations' the officer faces, especially in the 
nation's cities."  Her approach, however, distorts this balance. 
 
Accordingly, here, we conclude that Dwan's knowledge may be 
considered in the calculus of reasonable suspicion pursuant to 
the horizontal collective knowledge doctrine, but we decline to 
impute Lopez's knowledge to Doherty.  The defendant maintains 
that Lopez's knowledge may not be imputed to Doherty because 
there is no evidence that Lopez communicated the results of his 
search.  We agree with the defendant that Lopez's knowledge may 
not be imputed, but for a different reason:  there is no 
29 
 
evidence in the record indicating that Lopez communicated at all 
with Doherty or over channel six prior to the stop of the 
defendant.  Thus, despite being involved in a joint effort, the 
continuous communication requirement was not met, and Lopez's 
knowledge of the absence of people in the area of Victory Road 
therefore cannot be imputed to Doherty.  See Commonwealth v. 
Hawkins, 361 Mass. 384, 386-387 & n.3 (1972) (declining to 
impute knowledge about stolen bonds to officers who seized 
bonds, absent probable cause, where there was no evidence of 
communication or cooperative effort).  See, e.g., United States 
v. Villasenor, 608 F.3d 467, 476-477 (9th Cir.), cert. denied, 
562 U.S. 1020 (2010) (declining to aggregate knowledge of 
immigration and customs enforcement agents and inspectors of 
customs and border protection where "[t]he record [was] devoid 
of any communication" amongst agents). 
 
The defendant also argues that the motion judge did not 
find the predicate facts that would permit any application of 
the horizontal collective knowledge doctrine here.  
Specifically, the defendant maintains that, by omitting mention 
of the beard from her analysis of reasonable suspicion, the 
judge actually made a contrary finding that neither Doherty nor 
Dwan had had knowledge of the subsequent dispatches that 
reported that the suspect had facial hair.  The defendant 
contends that the judge's omission itself was a finding. 
30 
 
 
We do not read the judge's findings so narrowly.  The only 
finding the judge made with respect to the description of facial 
hair was in a footnote, in which the judge noted that "[t]here 
was no mention in the original broadcast about facial hair 
(emphasis added)."  Thus, it is unclear whether the judge found 
that Doherty heard the subsequent two broadcasts.  Even if we 
were to assume that this footnote was a finding that Doherty did 
not hear the subsequent broadcasts detailing the additional 
descriptions that mentioned facial hair, the record makes clear 
that Dwan did hear them, and thus, we impute his knowledge to 
Doherty. 
 
"[A]n appellate court may supplement a motion judge's 
subsidiary findings with evidence from the record that 'is 
uncontroverted and undisputed and where the judge explicitly or 
implicitly credited the witness's testimony.'"  Jones-Pannell, 
472 Mass. at 431, quoting Commonwealth v. Isaiah I., 448 Mass. 
334, 337 (2007).  Any supplemental facts taken from the record 
"may not contradict the motion judge's findings."  Commonwealth 
v. Garner, 490 Mass. 90, 94 (2022), citing Isaiah I., supra.  
Nor does "a general statement crediting witness testimony mean[] 
that every statement the witness makes on the stand is 
automatically a fact found by the motion judge."  Garner, supra. 
 
Here, the audio recordings from the dispatch, which were 
introduced at the hearing, as well as Dwan's testimony, confirm 
31 
 
that Dwan was actively engaged in communications with the 
dispatcher who relayed the later descriptions.  None of this 
information is contrary to any of the judge's findings or 
ultimate conclusions of law, and the judge did not reject any 
part of Dwan's testimony as not credible.  Accordingly, we can 
conclude, consistent with the judge's findings, that Dwan was 
aware that the suspect had been described as having facial hair.  
See Jones-Pannell, 472 Mass. at 431. 
 
Given this, Dwan's knowledge may be imputed to Doherty 
through the horizontal collective knowledge doctrine.  Dwan and 
Doherty were actively working on apprehending the suspect 
involved in the armed robbery; indeed, they arrived at the scene 
of the stop contemporaneously.  The two officers jointly 
conducted a patfrisk of the defendant's person and backpack.  
This is more than sufficient to be considered a joint 
investigation for a shared, mutual objective.  See Sandoval-
Venegas, 292 F.3d at 1104 (upholding arrest that was "the 
culmination of the efforts of two detectives who were working 
together, in close communication and consultation, and who were 
both present at the arrest").  Additionally, Dwan continuously 
provided updates over channel six about the status of his 
investigation, which Doherty testified to having monitored.  
That Dwan was in continued, close communication with channel 
six, and with Doherty upon arrival, further supports application 
32 
 
of the horizontal knowledge doctrine.  See id.  This was not a 
case where Dwan and Doherty were working in isolation and 
"merely happen[ed] to be investigating the same subject."  See 
Gillette, 245 F.3d at 1034.  Accordingly, Dwan's information 
that the suspect had a beard, and that no one else was outside 
on Morrissey Boulevard or Victory Road, may be imputed to 
Doherty. 
 
iii.  Over-all calculus of reasonable suspicion.  The 
defendant argues that, even taking account of all the 
circumstances, Doherty lacked reasonable suspicion at the time 
of the investigatory stop, and his motion to suppress should 
have been allowed.  We do not agree. 
 
The similarity of the physical description of the suspect 
to the defendant, the temporal and physical proximity of the 
defendant to the scene of the robbery, and the context of the 
stop gave rise to reasonable suspicion, with or without the 
information that the suspect had facial hair.  See Commonwealth 
v. Henley, 488 Mass. 95, 103 (2021) ("Although, standing alone, 
any one of these factors might not have been sufficient to 
justify the stop, when viewed as a whole, . . . they gave rise 
to reasonable suspicion"). 
 
We have cautioned that a match between a defendant's 
appearance and a general description alone does not amount to 
reasonable suspicion, particularly if that general description 
33 
 
could fit a large number of people in the area where the stop 
occurred.  See Commonwealth v. Warren, 475 Mass. 530, 535 (2016) 
(description of three Black males wearing dark clothing, with 
one wearing red hoodie, absent description of any facial 
features, hairstyles, height, weight, or other physical 
characteristics, was insufficient to establish reasonable 
suspicion); Commonwealth v. Cheek, 413 Mass. 492, 496 (1992) 
("the description of the suspect as a '[B]lack male with a black 
[three-quarter] length goose' could have fit a large number of 
men who reside in the Grove Hall section of Roxbury"). 
 
At the time of the stop here, however, Doherty knew that 
the suspect had been described as a Black male, twenty-eight or 
twenty-nine years old, with a medium build, and five feet, seven 
inches to five feet eight inches tall.  He also knew that the 
suspect had been described as having facial hair, wearing blue 
jeans7 and a blue hoodie, and carrying a silver firearm.  The 
defendant generally matched the description of the suspect, in 
terms of age, height, skin tone, build, and facial hair.  Thus, 
the correspondence between the defendant's appearance and the 
 
7 The judge found that the dispatched description of the 
suspect was for a male with dark jeans.  The 911 call placed by 
the victim, however, as well as the radio transmission and 
Doherty's testimony at the hearing "make clear that the report 
said that the jeans were blue."  Privette, 100 Mass. App. Ct. at 
223 n.3. 
34 
 
description of the suspect was not so generalized as to preclude 
giving rise to reasonable suspicion. 
 
Undoubtedly, the defendant's appearance did not match the 
description of the suspect in every particular.  The defendant 
was wearing a green sweater, black jeans,8 and a red plaid 
backpack.  In context, the absence of the red backpack in the 
broadcast description is of little significance.  Backpacks, 
like sunglasses, hats, or a mask, are easily worn, taken off, 
changed, or discarded.  See Commonwealth v. Staley, 98 Mass. 
App. Ct. 189, 192 (2020). 
 
In addition, as stated, the physical similarities between 
the defendant's appearance and the description of the suspect 
were supplemented by the defendant's geographic proximity to the 
location of the robbery within minutes of it having taken place.  
The defendant appears to suggest that his proximity to the scene 
weighs against a finding of reasonable suspicion, because had he 
been the robber, he would have traveled farther from the scene 
in the seven minutes that had elapsed since the robbery.  See 
Warren, 475 Mass. at 536-537 (stop of defendant one mile from 
scene, twenty-five minutes later, where there was no reported 
 
8 Doherty initially testified that the defendant was wearing 
blue jeans, but, on cross-examination, after having had his 
recollection refreshed by the booking sheet, Doherty testified 
that the defendant's jeans were black.  Both the Commonwealth 
and the defendant agree that the jeans he wore at the time of 
the stop were black. 
35 
 
flight path, had little weight in calculus of reasonable 
suspicion).  We are not convinced. 
 
Here, there was a reported path of flight, and the 
defendant was found seven minutes after the initial dispatch on 
a street directly behind the gasoline station that had been 
robbed.  The defendant's location was consistent with the 
reported flight path, which was in the direction of the pharmacy 
on Morrissey Boulevard.  Both the timing and the location of the 
stop in relation to the armed robbery thus weigh in favor of a 
finding of reasonable suspicion.  See Warren, 475 Mass. at 536 
("Proximity is accorded greater probative value in the 
reasonable suspicion calculus when the distance is short and the 
timing is close").  Indeed, given the other circumstances 
present here, the physical description of the defendant's 
height, build, age, skin tone, clothing, and firearm was 
sufficient to establish reasonable suspicion even without any 
mention that the suspect had facial hair. 
 
The defendant argues that being the only person in the area 
at that hour of the morning is not dispositive.  We agree that, 
taken alone, his location at the time of the stop would be 
insufficient to warrant a finding of reasonable suspicion.  But, 
given that he was the only person in the vicinity of the robbery 
at 3:43 A.M., in the rain, within seven minutes of the reported 
36 
 
robbery, the articulable facts combine to establish reasonable 
suspicion that the defendant had committed the armed robbery. 
Order denying motion to 
  suppress affirmed. 
 
 
CYPHER, J. (concurring in part and dissenting in part).  I 
agree with the court that Officer Brian Doherty had sufficient 
reasonable suspicion to stop the defendant as a suspect in the 
armed robbery.1  I disagree, however, that the court should 
 
1 I agree with the court and with Justice Wendlandt that 
reasonable suspicion in this case is not dependent on the 
collective knowledge doctrine (therefore, I would have declined 
to reach the application of the doctrine to this case and 
beyond).  At around 3:36 A.M., Doherty received a radio 
transmission indicating that there was an armed robbery of a 
gasoline station on Morrissey Boulevard in the Dorchester 
section of Boston, describing the suspect as "a Black male, late 
twenties, medium build, five foot seven, blue hoodie, blue 
jeans, on foot toward[]" a pharmacy.  Doherty was listening to 
the police department radio channel as he headed to the area and 
heard Lieutenant (then Sergeant) Daryl Dwan report that he did 
not see anyone on Morrissey Boulevard.  Canvassing the nearby 
Clam Point neighborhood, he drove through about nine additional 
streets without seeing a single person.  Approximately seven 
minutes after the dispatch, Doherty saw the defendant on a 
street close to the gasoline station and easily accessible by an 
opening in a fence or by walking along several streets.  The 
defendant is a Black male, five feet, eleven inches tall, 220 
pounds, and was thirty-two years old at the time, wearing a dark 
sweater and jeans, and was the only person on the street at 
approximately 3:30 A.M.  Even without considering the 
defendant's beard, there was reasonable suspicion to stop him.  
Commonwealth v. Evelyn, 485 Mass. 691, 704-705 (2020) (defendant 
one-half mile away from location of crime thirteen minutes after 
it occurred supported reasonable suspicion).  Contrast 
Commonwealth v. Warren, 475 Mass. 530, 535-536 (2016) (no 
reasonable suspicion where description was vague and did not 
include "any information about facial features, hairstyles, skin 
tone, height, weight, or other physical characteristics," but 
recognizing "[p]roximity is accorded greater probative value 
. . . when the distance is short and the timing is close"). 
 
Nonetheless, considering the record, it is very likely that 
Doherty heard the dispatch including the description of facial 
hair.  The description of the suspect having facial hair was 
broadcast on the department channel at around 3:38 A.M., two 
 
2 
 
dismantle the collective knowledge doctrine as it has been 
discussed and appropriately applied in cases in this 
Commonwealth for more than fifty years.  I would uphold the 
collective knowledge doctrine in situations where officers are 
engaged in a cooperative effort.  I would not dissect whether 
officers are in sufficiently "close and continuous communication 
with each other" about their "shared objective," nor would I 
examine whether the acting officer is aware "of at least some of 
the critical facts" in determining whether to aggregate their 
knowledge.  Ante at    .  I respectfully dissent. 
 
I begin my analysis by considering the theoretical 
framework in which search and seizure analysis typically has 
been conducted, whether under the Fourth Amendment to the United 
States Constitution or art. 14 of our Declaration of Rights.  
Although the discussion of the utility of the collective 
knowledge doctrine concerns each officer's subjective knowledge 
 
minutes after the first description, and at least three minutes 
before Doherty stopped the defendant.  Although Doherty agreed 
with defense counsel on cross-examination that the first 
description was the only transmittal he heard before he stopped 
the defendant, he testified on direct examination, without 
prompting, that the call was for a man "with a beard," and 
affirmed that description on cross-examination.  The motion 
judge made no finding addressing Doherty's knowledge of facial 
hair.  Commonwealth v. Jones-Pannell, 472 Mass. 429, 431 (2015) 
(appellate court may supplement motion judge's findings of fact 
with uncontroverted record evidence where judge explicitly 
credited witness's testimony and where facts do not detract from 
judge's ultimate findings). 
3 
 
when working together with others, the reasons we do not 
consider the intent or motive of individual officers apply 
equally to knowledge and are instructive.  See, e.g., 
Commonwealth v. Long, 485 Mass. 711, 724 n.9 (2020) (in 
determining whether traffic stop was racially discriminatory, 
judge may consider whether officer observed or followed vehicle 
for extended period of time or whether officer would have been 
able to note defendant's race). 
"Fourth Amendment doctrine, given force and effect by the 
exclusionary rule," is intended primarily to regulate the day-
to-day activities of police officers and should be expressed in 
readily applicable terms for implementation by law enforcement.  
Clancy, The Purpose of the Fourth Amendment and Crafting Rules 
to Implement That Purpose, 48 U. Rich. L. Rev. 479, 505 (Jan. 
2014), quoting New York v. Belton, 453 U.S. 454, 458 (1981). 
"A highly sophisticated set of rules, qualified by all 
sorts of ifs, ands, and buts and requiring the drawing of 
subtle nuances and hairline distinctions, may be the sort 
of heady stuff upon which the facile minds of lawyers and 
judges eagerly feed, but they may be literally impossible 
of application by the officer in the field." 
 
Clancy, supra, quoting Belton, supra. 
Keeping that purpose in mind, "one of the main principles 
of Fourth Amendment analysis for many years has been the 
measurement of a police officer's intent by examining the 
objective aspects of the encounter, as opposed to inquiry into 
4 
 
the officer's actual, subjective intent."  T.K. Clancy, The 
Fourth Amendment § 11.6.2.1, at 767 (3d ed. 2017).  See Brigham 
City v. Stuart, 547 U.S. 398, 404 (2006), quoting Scott v. 
United States, 436 U.S. 128, 138 (1978) ("An action is 
'reasonable' under the Fourth Amendment, regardless of the 
individual officer's state of mind, 'as long as the 
circumstances, viewed objectively, justify [the] action'" 
[emphasis added]); Indianapolis v. Edmond, 531 U.S. 32, 45 
(2000) ("individual officer's subjective intentions are 
irrelevant to the Fourth Amendment validity of a traffic stop 
that is justified objectively by probable cause to believe a 
traffic violation has occurred"); Bond v. United States, 529 
U.S. 334, 338 n.2 (2000) ("The parties properly agree that the 
subjective intent of the law enforcement officer is irrelevant 
in determining whether that officer's actions violate the Fourth 
Amendment"); Whren v. United States, 517 U.S. 806, 812-813 
(1996) (decisions released by Court "foreclose any argument that 
the constitutional reasonableness of traffic stops depends on 
the actual motivations of the individual officers involved"); 
Newton, The Real-World Fourth Amendment, 43 Hastings Const. L.Q. 
759, 770-771 (2016) ("As a general matter, courts assess whether 
the Fourth Amendment was violated in a particular case by 
applying an 'objective' standard. . . .  [T]he 'subjective' 
mental states of both the police officers and the persons they 
5 
 
interacted with are generally irrelevant to the Fourth Amendment 
analysis"); Tomkovicz, Rehnquist's Fourth:  A Portrait of the 
Justice as a Law and Order Man, 82 Miss. L.J. 359, 404-405 
(2013), quoting Graham v. Connor, 490 U.S. 386, 396-397 (1989) 
(discussing Justice Rehnquist's approach to Fourth Amendment, 
"[e]valuations of reasonableness called for 'objective' 
inquiries that pay 'careful attention to the facts and 
circumstances of each particular case'").  But see Dix, 
Subjective "Intent" as a Component of Fourth Amendment 
Reasonableness, 76 Miss. L.J. 373 (2006) (critical analysis of 
objective standard); Kinports, Criminal Procedure in 
Perspective, 98 J. Crim. L. & Criminology 71 (2007) (arguing 
Court shifts from objective to subjective tests); Raigrodski, 
Reasonableness and Objectivity:  A Feminist Discourse of the 
Fourth Amendment, 17 Tex. J. Women & L. 153 (2008) (discussing 
partiality in "objective" determinations of reasonableness); 
Kerr, The Questionable Objectivity of Fourth Amendment Law, 99 
Tex. L. Rev. 447 (Feb. 2021) (challenging true objectivity in 
Fourth Amendment doctrine as applied by Court).  "[A]lthough the 
framing-era sources did not always agree on the details of the 
criteria for regulating searches and seizures, they were united 
in seeking objective criteria to measure the propriety of 
governmental actions."  Clancy, The Framers' Intent:  John 
6 
 
Adams, His Era, and the Fourth Amendment, 86 Ind. L.J. 979, 980 
(2011). 
"Reasonableness and the balancing of interests under the 
Fourth Amendment is an objective inquiry."  1 J.W. Hall, Search 
and Seizure § 2.14 (5th ed. Supp. Oct. 2013).  This inquiry is 
fact bound, and "is measured in objective terms by examining the 
totality of the circumstances."  Id., quoting Ohio v. Robinette, 
519 U.S. 33, 39 (1996).  "[T]he calculus of reasonableness must 
embody allowance for the fact that police officers are often 
forced to make split-second judgments -- in circumstances that 
are tense, uncertain, and rapidly evolving."  Kentucky v. King, 
563 U.S. 452, 466 (2011), quoting Graham, 490 U.S. at 396-397.  
The subjective intent of the officers is generally irrelevant; 
"the only real questions are what do the objective facts show 
and is this objectively reasonable?"  Hall, supra.  See 68 Am. 
Jur. 2d Searches and Seizures § 13 (2020) ("An action is 
reasonable under the Fourth Amendment regardless of the 
individual officer's state of mind as long as the circumstances, 
viewed objectively, justify the action; the officer's subjective 
motivation is irrelevant").  Even where an officer declared at 
the hearing on a motion to suppress that the officer did not 
believe he or she had sufficient facts to amount to probable 
cause, that personal opinion is not fatal to the Commonwealth's 
7 
 
case.  2 W.R. LaFave, Search and Seizure § 3.2(b), at 46 (6th 
ed. 2020). 
"[T]he mere subjective conclusions of a police officer 
concerning the existence of probable cause is not binding 
on this court which must independently scrutinize the 
objective facts to determine the existence of probable 
cause. . . .  Moreover, since the courts have never 
hesitated to overrule an officer's determination of 
probable cause when none exists, consistency suggests that 
a court may also find probable cause in spite of an 
officer's judgment that none exists." 
 
LaFave, supra, quoting United States ex rel. Senk v. Brierley, 
381 F. Supp. 447, 463 (M.D. Pa. 1974).  See Re, Fourth Amendment 
Fairness, 116 Mich. L. Rev. 1409, 1460 (June 2018) ("[P]olice 
can act reasonably without being motivated by the considerations 
that make their conduct reasonable. . . .  [Where there are 
reasonable grounds to act,] requiring that the officer correctly 
glean the proper basis for her actions would not afford innocent 
persons any greater protection, and insistence on police 
perfection would create windfalls for wrongdoers.  This default 
indifference to police motivation aligns with the case law, 
which focuses on objectively available reasons for action"). 
Correspondingly, in Massachusetts, "[s]ubjective intentions 
play no role" in the reasonable suspicion analysis.  J.A. 
Grasso, Jr., & C.M. McEvoy, Suppression Matters Under 
Massachusetts Law § 4-3[b] (2022 ed.).  See Commonwealth v. 
Buckley, 478 Mass. 861, 865-866 (2018) ("under the authorization 
test, a stop is reasonable under art. 14 as long as there is a 
8 
 
legal justification for it"); Commonwealth v. Cruz, 459 Mass. 
459, 462 n.7 (2011) ("The subjective intentions of police are 
irrelevant so long as their actions were objectively 
reasonable").  "Evaluating the validity of police conduct on the 
basis of objective facts and circumstances, without 
consideration of the subjective motivations underlying that 
conduct, is justified in part based on the significant 
evidentiary difficulties such an inquiry into police motives 
would often entail."  Buckley, supra at 867.  Only recently have 
we made an exception to the objective standard in search and 
seizure cases in which a defendant alleged race as the reason 
for a traffic stop based on a pretext; this exception is founded 
not on art. 14 or the Fourth Amendment, but on our equal 
protection jurisprudence set out in arts. 1 and 10 of the 
Declaration of Rights and the Fourteenth Amendment to the United 
States Constitution.  Long, 485 Mass. at 715, 729.2  The analysis 
 
2 See Long, 485 Mass. at 713 (establishing revised test for 
defendants seeking to suppress evidence obtained as result of 
racially motivated traffic stop); Commonwealth v. Lora, 451 
Mass. 425, 426 (2008) (exclusionary rule applies to evidence 
from traffic stop violative of equal protection where stop was 
product of selective enforcement based on race).  In inventory 
and special needs searches and administrative inspections, the 
Supreme Court has looked to subjective intent in analyzing the 
validity of government action.  See Brigham City, 547 U.S. at 
405, quoting Edmond, 531 U.S. at 46 ("we have held in the 
context of programmatic searches conducted without 
individualized suspicion -- such as checkpoints to combat drunk 
driving or drug trafficking -- that 'an inquiry into a 
 
9 
 
in such cases occasionally refers to an officer's intent, 
motivation, or state of mind; and in some instances, the 
officer's knowledge.  See id. at 724-725 (listing factors judges 
should consider in applying totality of circumstances test to 
determine whether traffic stop was violative of equal 
protection); Commonwealth v. White, 469 Mass. 96, 101-102 (2014) 
(officer's examination of pills transformed search from 
inventory into investigatory); Commonwealth v. Judge, 95 Mass. 
App. Ct. 103, 108 (2019) (administrative and special needs 
searches may not become pretext for investigative search).  See 
also Newton, The Real-World Fourth Amendment, supra at 771 
("There are some rare exceptions to the general 'objective' 
nature of legal analysis under the Fourth Amendment," such as 
police roadblocks). 
 
programmatic purpose' is sometimes appropriate"); Whren, 517 
U.S. at 812 ("we [have] never held, outside the context of 
inventory search or administrative inspection . . . that an 
officer's motive invalidates objectively justifiable behavior 
under the Fourth Amendment"); Florida v. Wells, 495 U.S. 1, 4 
(1990) (inventory search may not be "ruse for a general 
rummaging in order to discover incriminating evidence").  See 
also Commonwealth v. Judge, 95 Mass. App. Ct. 103, 108 (2019), 
quoting Commonwealth v. Carkhuff, 441 Mass. 122, 126 (2004) 
("Administrative and special needs searches 'must be conducted 
as part of a scheme that has as its purpose something "other 
than the gathering of evidence for criminal prosecutions"'").  
But see Commonwealth v. Feliz, 481 Mass. 689, 700 n.17 (2019), 
S.C., 486 Mass. 510 (2020) ("We have yet to justify searches of 
individuals on the basis of the special needs exception"). 
10 
 
In other words, we always have examined the totality of the 
circumstances to determine whether a search or seizure was 
reasonable.  The reason for conducting an objective analysis 
includes the recognition that the Fourth Amendment, and art. 14, 
regulate conduct rather than thoughts.  See Ashcroft v. al-Kidd, 
563 U.S. 731, 736 (2011).  "[I]njecting subjectivity into Fourth 
Amendment reasonableness would require officers to 'act on 
necessary spurs of the moment with all the knowledge and acuity 
of constitutional lawyers'" (citation omitted).  Barmore, 
Authoritarian Pretext and the Fourth Amendment, 51 Harv. C.R.-
C.L. L. Rev. 273, 297 (2016). 
Additionally, analyzing the intent behind an officer's 
actions "could cause unacceptable variation in the Fourth 
Amendment's application" where its focus on objectivity is meant 
to promote "evenhanded, uniform enforcement of the law."  
Barmore, supra at 298, quoting Ashcroft, 563 U.S. at 736.  As a 
practical matter, determining the nature of subjective motives 
underlying an individual officer's action is difficult.  See 
Brigham City, 547 U.S. at 405 ("It . . . does not matter here -- 
even if their subjective motives could be so neatly unraveled -- 
whether the officers entered the kitchen to arrest respondents 
and gather evidence against them or to assist the injured and 
prevent further violence"); Harlow v. Fitzgerald, 457 U.S. 800, 
816-817 (1982) (in discussing qualified immunity, "[j]udicial 
11 
 
inquiry into subjective motivation therefore may entail broad-
ranging discovery and deposing of numerous persons, including an 
official's professional colleagues," which may be "peculiarly 
disruptive of effective government"). 
For the same reasons, when several officers are working 
together, it will be difficult to decipher the precise knowledge 
that each individual officer had at various points in the 
investigation, whether the acting officer had knowledge of "some 
of the critical facts," and whether the communications between 
the officers were sufficiently close and continuous and touched 
on the "objective" of the police with respect to the 
investigation.  Ante at    .  Taking into consideration the 
knowledge of all the officers involved in a police action is 
consistent with an objective analysis of the totality of the 
circumstances.  See Coleman, Beyond the Four Corners:  Objective 
Good Faith Analysis or Subjective Erosion of Fourth Amendment 
Protections?, 54 Mercer L. Rev. 1719, 1724 (2003) ("the 
objective standard is framed by the officer's knowledge and 
understanding of the requirements of the Fourth Amendment. . . .  
Objective good faith, then, rests on a foundation of Fourth 
Amendment compliance, not individualized, subjective knowledge 
of facts known only to the officer"); LaFave, supra at § 9.5(a), 
at 660-661 ("Certainly it is clear beyond question that the 
'reasonable belief' required for arrest is not to be determined 
12 
 
by what the arresting officer did or did not believe, but rather 
by whether the available facts would 'warrant [an officer] of 
reasonable caution in the belief' that the person arrested had 
committed an offense. . . .  [The reasonable suspicion] test, as 
is the case with the legal standard for arrest, is purely 
objective and thus there is no requirement that an actual 
suspicion by the officer be shown" [citation omitted]); R.G. 
Stearns, Massachusetts Criminal Law:  A Prosecutor's Guide, 
Threshold Inquiries (42d ed. 2023), quoting Commonwealth v. 
Stoute, 422 Mass. 782, 790 (1996) ("facts must be assessed in 
light of the collective knowledge of the officers involved" and 
"[t]he test is an objective one, 'view[ing] the circumstances as 
a whole'").  Application of the court's new rule shifts the 
Fourth Amendment and art. 14 focus from the objective conduct of 
the police to the subjective thought process of the first 
officer to reach the suspect, and too closely examines the 
precise frequency and content of communications between officers 
cooperating in an investigation.  I would keep the existing 
doctrine in place, in which a judge need not consider the inner 
workings of the minds of each individual officer at the relevant 
time, but the collective knowledge of all officers working 
together at the time of a stop, search, or arrest.  Although I 
think that communication between officers is a good indicator 
that they are acting as a team, to inquire into the sufficiency 
13 
 
of the communications between collaborating officers in order to 
aggregate their knowledge will prove difficult for judges trying 
to apply the new rule, and for officers striving to integrate 
the court's holding into their daily practices. 
 
In United States v. Cook, 277 F.3d 82, 86 (1st Cir. 2002), 
the United States Court of Appeals for the First Circuit 
discussed the reasoning supporting the aggregation of knowledge 
among officers who are collaborating in a joint effort and held 
that the knowledge of each officer should be imputed to all 
officers jointly involved in an investigative stop.  "As the 
Supreme Court has repeatedly noted, common sense and practical 
considerations must guide judgments about the reasonableness of 
searches and seizures."  Id.  Imputing the knowledge of all the 
officers working together is practical where "[i]nvestigative 
stops generally occur in a dynamic environment marked by the 
potential for violence"; it would make little sense to base the 
legitimacy of the stop solely on the knowledge of the first 
officer to reach the suspect.  Id.  This takes into account the 
reality of many investigative stops conducted by multiple 
officers:  "rarely will [officers] have an opportunity to confer 
during the course of the stop."  Id.3 
 
3 Several jurisdictions have upheld the horizontal 
collective knowledge doctrine without requiring communication of 
specific facts among officers so long as they are working 
 
14 
 
 
together.  See United States v. Whitfield, 634 F.3d 741, 746 (3d 
Cir. 2010) ("It would make little sense to decline to apply the 
collective knowledge doctrine in a fast-paced, dynamic situation 
such as we have before us, in which the officers worked together 
as a unified and tight-knit team; indeed, it would be 
impractical to expect an officer in such a situation to 
communicate to the other officers every fact that could be 
pertinent in a subsequent reasonable suspicion analysis"); 
United States v. Nunez, 455 F.3d 1223, 1226 (11th Cir. 2006) 
(reasonable suspicion determined from "collective knowledge of 
the officers"); United States v. Ledford, 218 F.3d 684, 689 (7th 
Cir. 2000) ("Because the search was a joint endeavor, the court 
may properly consider what . . . the other officers knew [in 
addition to the officer who opened the trunk during the 
search]. . . .  Were it otherwise, the validity of such jointly 
conducted searches might turn on the fortuity of which officer 
happened to open a trunk or door, notwithstanding the fact that 
he and his colleagues were acting in concert").  But see United 
States v. Ellis, 499 F.3d 686, 690 (7th Cir. 2007) (refusing to 
impute knowledge of one officer to another to validate decision 
to enter home because they were not in communication regarding 
suspect); United States v. Roberts, 410 F. Supp. 3d 1268, 1282 
(N.D. Fla. 2019), quoting United States v. Willis, 759 F.2d 
1486, 1494 (11th Cir. 1985) ("collective knowledge doctrine 
applies to cases in which the government agents maintained 'at 
least a minimal level of communication during their 
investigation'").  See also In re M.E.B., 638 A.2d 1123, 1129-
1133 (D.C. 1993), cert. denied, 513 U.S. 883 (1994) (aggregating 
uncommunicated information between officers, holding that this 
result "recognizes that when faced with a fast moving sequence 
of events involving a number of police officers, a citizen's 
rights are protected if, at the time of the intrusion, the 
information collectively known to the police is constitutionally 
sufficient to justify that intrusion"); State v. Goff, 129 
S.W.3d 857, 863-864 (Mo. 2004) ("collective information in the 
possession of those with a nexus to the investigation can be 
considered in determining whether reasonable suspicion existed," 
rejecting defendant's "argument that each officer is required to 
repeat his or her information to the officer making the stop in 
order to make the stop a constitutional one"); State v. 
Fioravanti, 46 N.J. 109, 122 (1965), cert. denied, 384 U.S. 919 
(1966) ("Probable cause must be judged on the basis of 
[officers'] composite information, and if that knowledge in its 
totality shows probable cause, a police[ officer] who makes the 
arrest upon an ensuing order to do so, acts upon probable 
 
15 
 
This reasoning closely tracks the reasoning of the Supreme 
Court in United States v. Hensley, 469 U.S. 221, 231-232 (1985), 
in which it expanded on the collective knowledge doctrine by 
allowing reliance on a flyer or bulletin issued by another 
officer or police department to support a stop so long as the 
flyer or bulletin was issued on the basis of articulable facts 
supporting a reasonable suspicion.  In making this 
determination, the Court recognized that the rule is a matter of 
"common sense," noting "effective law enforcement cannot be 
conducted unless police officers can act on directions and 
information transmitted by one officer to another and that 
officers, who must often act swiftly, cannot be expected to 
cross-examine their fellow officers about the foundation for the 
transmitted information."  Id. at 231, quoting United States v. 
Robinson, 536 F.2d 1298, 1299 (9th Cir. 1976).  Although in 
Hensley, the Court was grappling with the vertical collective 
knowledge doctrine, aggregating the knowledge of officers acting 
 
cause"); People v. Gittens, 211 A.D.2d 242, 245-246 (N.Y. 1995) 
(knowledge of officers "working in close temporal and spatial 
proximity to one another" may be aggregated in reviewing 
propriety of action taken); Woodward v. State, 668 S.W.2d 337, 
344 (Tex. Crim. App. 1982), cert. denied, 469 U.S. 1181 (1985) 
("when there has been some cooperation between law enforcement 
agencies or between members of the same agency, the sum of the 
information known to the cooperating agencies or officers at the 
time of an arrest or search by any of the officers involved is 
to be considered in determining whether there was sufficient 
probable cause therefor"). 
16 
 
together also recognizes the need for officers to act "swiftly" 
and efficiently.  Hensley, supra. 
 
In Massachusetts, as in other jurisdictions, when analyzing 
probable cause, we look to the entire set of facts and 
circumstances within the knowledge of the police.  "[P]robable 
cause exists where, at the moment of arrest, the facts and 
circumstances within the knowledge of the police are enough to 
warrant a prudent person in believing that the individual 
arrested has committed or was committing an offense."  
Commonwealth v. Santaliz, 413 Mass. 238, 241 (1992), quoting 
Commonwealth v. Storey, 378 Mass. 312, 321 (1979), cert. denied, 
446 U.S. 955 (1980).  In discussing the collective knowledge 
doctrine, the Appeals Court has referred to Santaliz and the 
consideration of the "whole silent movie" as important to the 
probable cause determination.  Commonwealth v. Gant, 51 Mass. 
App. Ct. 314, 318 (2001) (aggregating observations of two 
separate officers to get to probable cause because "[b]oth 
officers were engaged in a cooperative effort in the 
investigation of this incident so that we may consider the 
complete picture"); Commonwealth v. Garcia, 34 Mass. App. Ct. 
386, 393 n.8 (1993) (noting collective knowledge doctrine and 
probable cause standard).  "A reviewing court may consider the 
'whole silent movie,' [Santaliz, supra at 242,] disclosed to the 
eyes of an experienced . . . investigator rather than 
17 
 
'scrutinize in isolation' each of the facts and circumstances 
known to the officers."  Gant, supra, quoting Commonwealth v. 
Kennedy, 426 Mass. 703, 708 (1998).  See Hall, supra at § 6.10 
("Probable cause is viewed objectively by reviewing courts and 
is not based on the officer's subjective belief.  If the rule 
were otherwise, the citizenry would have significantly diluted 
Fourth Amendment protection depending on whether the officer 
chose to obtain a warrant before the arrest or search based on 
subjective good faith.  Only objective facts can be effectively 
reviewed").  The court's approach requires a judge hearing 
testimony in a motion to suppress, or a reviewing court, to 
determine the extent of cooperation and communication for every 
police move.  Contrast Commonwealth v. Montoya, 464 Mass. 566, 
576 (2013) (imputing knowledge of one officer to another, 
"regardless of whether" it was communicated immediately by 
radio).4 
 
4 The facts of the present case underscore the difficulty in 
determining precisely what was communicated to each officer at 
which point during the investigation.  Determining whether each 
officer heard the communication regarding the beard before they 
approached the defendant brings the court into murky waters.  
Indeed, the motion judge avoided making any such finding.  
Although the court does not entirely discard the horizontal 
collective knowledge doctrine, the new rule still falls subject 
to this difficulty.  In order to apply the doctrine, a judge 
will have to determine whether the acting officer had "critical 
information" supporting the intrusion and discern whether that 
officer was in continuous close communication with the other 
officers (with knowledge) specifically with respect to their 
 
18 
 
Similarly, when ascertaining whether reasonable suspicion 
was sufficient, we have objectively examined the totality of the 
specific, articulable facts presented.  Commonwealth v. Meneus, 
476 Mass. 231, 235 (2017).  "The subjective intentions of police 
are irrelevant so long as their actions were objectively 
reasonable."  Cruz, 459 Mass. at 462 n.7.  It is of no matter 
whether an officer is acting in "good faith."  Commonwealth v. 
Grandison, 433 Mass. 135, 139 (2001).  See Commonwealth v. 
Gentile, 466 Mass. 817, 822 (2014).  "Reasonable suspicion is 
measured by the 'totality of the circumstances' and from the 
collective knowledge of the officers involved in the stop."  
K. Wallentine, Street Legal:  A Guide to Pre-trial Criminal 
Procedure for Police, Prosecutors, and Defenders 7 (2d ed. 
2020), quoting United States v. Sokolow, 490 U.S. 1, 2 (1989). 
With these principles in mind, aggregating the knowledge of 
officers working together in a cooperative effort in determining 
whether probable cause or reasonable suspicion was sufficient at 
the time of a stop or arrest conforms with our practice of 
analyzing a situation objectively, without regard to the 
subjective thought process of each separate officer involved.  
To confine the reasonable suspicion or probable cause analysis 
 
shared objective.  Ante at    .  This requires the judge to 
delve into the subjective thought process of not one, but 
several different officers. 
19 
 
to the facts known by the first officer to approach a suspect or 
to those known by an officer with whom he was in continuous, 
close communications with, when that officer is working 
collaboratively with additional officers, would depreciate the 
objectivity of the analysis.5 
Contrary to the defendant's assertion that Massachusetts 
dramatically has expanded and "strayed from its original 
efficiency rationale," Massachusetts applied the collective 
knowledge doctrine before the Supreme Court discussed the 
doctrine in Whiteley v. Warden, Wyo. State Penitentiary, 401 
U.S. 560, 568 (1971).  See Stearns, supra, Searches Incident to 
Arrest ("Massachusetts cases apply the collective knowledge 
 
5 I agree with the court that the inevitable discovery 
exception is not an adequate substitute for the horizontal 
collective knowledge doctrine.  Where evidence is discovered in 
a manner that would compel its exclusion at a criminal trial 
against the defendant, it may be admissible if the Commonwealth 
can show by a preponderance of the evidence "that discovery of 
the evidence by lawful means was certain as a practical matter, 
'the officers did not act in bad faith to accelerate the 
discovery of evidence, and the particular constitutional 
violation is not so severe as to require suppression.'"  
Commonwealth v. Hernandez, 473 Mass. 379, 386 (2015), quoting 
Commonwealth v. Sbordone, 424 Mass. 802, 810 (1997).  "This is a 
'demanding test.'"  Hernandez, supra, quoting Commonwealth v. 
Balicki, 436 Mass. 1, 16 (2002).  In a situation where several 
officers are working as a team in pursuit of a suspect, and one 
officer catches the suspect, it would be near impossible for the 
Commonwealth to prove that his apprehension by another of the 
officers was practically certain.  See Hurlburt v. State, 425 
P.3d 189, 194-195 (Alaska Ct. App. 2018) (discussing aggregation 
of knowledge of collaborating officers based on "inevitable 
discovery" rationale only applies to "unusual facts"). 
20 
 
doctrine in both the vertical and horizontal contexts, usually 
without drawing a formal distinction between the two").  In 
Commonwealth v. McDermott, 347 Mass. 246, 249-250 (1964), the 
court discussed an arrest pursuant to a lawful warrant.  The 
warrant permitted the arrest of any individual at a particular 
location "participating in any form of gaming," or any person 
present if gaming materials were found.  Id. at 247.  The first 
trooper on the scene saw the defendant registering bets.  Id. at 
249.  When two police lieutenants arrived, the trooper told them 
the defendant had "the stuff in his pockets."  Id. at 248.  As 
the lieutenants questioned the defendant, the trooper observed 
booking paraphernalia, notebooks, and personal belongings of the 
defendant spread out on a counter.  Id.  The lieutenants, not 
the trooper, subsequently arrested him.  Id.  The court held, 
"It is without significance that [the trooper] was not [the] one 
who made the arrest.  The three officers were engaged in a 
cooperative effort in the performance of their duty.  The 
knowledge of one was the knowledge of all."  Id. at 249.  See 
Commonwealth v. Lanoue, 356 Mass. 337, 340 (1969) ("unnecessary 
for the detaining officer to know all the information pertaining 
to the incident" because knowledge of one is knowledge of all); 
Commonwealth v. Ballou, 350 Mass. 751, 757 (1966), cert. denied, 
385 U.S. 1031 (1967) ("elementary rule of composite knowledge of 
21 
 
police officers engaged in a cooperative effort, where the 
knowledge of one may be the knowledge of all"). 
The court also has recognized certain circumstances in 
which the collective knowledge doctrine may not be applied.  In 
Commonwealth v. Hawkins, 361 Mass. 384, 385 (1972), officers 
searched the defendant's apartment pursuant to a warrant 
authorizing a search for drugs.  The officers did not find any 
drugs but did find an envelope containing United States savings 
bonds with names and addresses that did not match that of the 
defendant.  Id.  Another officer looked up the telephone number 
of one of the persons whose name and address was indicated on 
the bonds, and after a telephone conversation with the victim, 
the defendant was arrested.  Id.  Before the officer made the 
telephone call, the officers did not know that the bonds were 
stolen.  Previously, the victim had reported the stolen bonds at 
a police station; none of the searching officers was aware of 
that report.  Id. at 385-386.  The court held that the 
collective knowledge doctrine could not be applied to aggregate 
the knowledge of the officers because "the police were not aware 
of the theft reported to station 9 nor were they engaged in a 
cooperative effort with officers in connection with the stolen 
bonds who did have this knowledge."  Id. at 387. 
Where officers are not engaged in a cooperative effort, the 
court shall not apply the doctrine, thus limiting the danger of 
22 
 
unconstitutional searches and seizures.  Cf. Parsons v. United 
States, 15 A.3d 276, 279, 281 (D.C. 2011) (trial court applied 
collective knowledge doctrine improperly); Stearns, supra, 
Searches Incident to Arrest ("While the 'fellow officer' rule 
generally works to the advantage of police, it offers no 
protection when the arresting officer acts at another officer's 
deficient directions or stale or inaccurate information").  
There is no need for the creation of the complex and perplexing 
new rule that the court chooses to impose here.6  The court's 
refusal in Hawkins to apply the collective knowledge doctrine 
where officers were not engaged in a cooperative effort 
 
6 It is worth noting that some of the cases relied on by the 
court do not require such an extensive inquiry into the level of 
communication between officers acting as a team, or the 
sufficiency of the acting officer's knowledge of critical facts 
on his or her own.  See United States v. Ibarra, 493 F.3d 526, 
530 (5th Cir. 2007) (requiring only "some degree of 
communication" between arresting officer and officer who has 
knowledge of all necessary facts); United States v. Gillette, 
245 F.3d 1032, 1034 (8th Cir.), cert. denied, 534 U.S. 982 
(2001) (requiring "some degree of communication" to ensure 
officers functioning as "search team"); State v. Breeding, 200 
So. 3d 1193, 1200 (Ala. Crim. App. 2015), quoting United States 
v. Esle, 743 F.2d 1465, 1476 (11th Cir. 1984) (look to 
collective knowledge of officers where group of officers 
conducting operation and "there is at least minimal 
communication among them").  In Gillette, where one officer 
obtained consent to search vehicles, and another acting officer 
responded to a call for backup and immediately started searching 
the vehicles without knowledge of the consent, the court held 
that "there was the requisite degree of communication" between 
the officers to render the acting officer a member of the team, 
and to uphold the search.  Id. at 1033-1034. 
23 
 
demonstrates that aggregating the knowledge of officers working 
together complies with art. 14. 
For over fifty years, Massachusetts courts consistently 
have applied this doctrine in a horizontal manner where 
appropriate.  In Commonwealth v. Wooden, 13 Mass. App. Ct. 417, 
418 (1982), three police officers -- Saunders, Williams, and 
Callanan -- were patrolling when the defendant and another man 
drew their attention.  Saunders saw that the other man had 
something in his hand that he was showing to the defendant.  Id.  
When the men noticed the unmarked cruiser in which the officers 
were riding, they hurriedly moved down the street.  Id.  
Saunders saw the man drop a manila envelope.  Id.  Williams saw 
the defendant had something clenched in his hand and appeared to 
be putting something in his pocket.  Id. 
The officers got out of the car, and Saunders opened the 
manila envelope, finding white powder in several wrapped 
packages.  Wooden, 13 Mass. App. Ct. at 418.  Saunders placed 
both the defendant and the other man under arrest.  Id.  
Searching the defendant after his arrest, Williams found packets 
of cocaine and marijuana in the defendant's pockets.  Id. at 
418-419.  The court recognized that Saunders personally did not 
know that the defendant was clenching his hand and putting 
something into his pockets.  Id. at 421 ("[I]f Williams had been 
acting alone, he could not have arrested either [party] without 
24 
 
knowledge of the contents of the discarded envelope . . . .  If 
[Saunders] act[ed] alone, he could not have arrested the 
defendant on the sole basis of the contents of the envelope 
dropped by [the other man]").  Because "Saunders and Williams 
were working in concert, and they were within an arm's reach of 
each other as well as the suspects whom they were confronting," 
the court held that the knowledge of each officer could be 
imputed to the other.  Id. at 421-422, quoting W.R. LaFave, 
Search and Seizure § 3.5 (c), at 633 (1978) ("They were 'in a 
close time-space proximity to the questioned arrest [and] 
search'"). 
In Commonwealth v. Rivet, 30 Mass. App. Ct. 973, 975 
(1991), the Appeals Court rejected an argument made by the 
defendant that knowledge of the officers should not be 
aggregated because they did not communicate the known 
information to one another.  Officers Coyle and Dawes both 
responded to a crash scene, and both determined that there was 
probable cause to arrest the defendant for operating a motor 
vehicle while under the influence of intoxicating liquor.  Id. 
at 974.  Coyle arrived first and spoke with the defendant, who 
told him that he had drunk one beer; during their conversation, 
Coyle noticed that the defendant's eyes were glassy and arrested 
him.  Id.  When Dawes arrived, approximately ten to fifteen 
minutes before the defendant's arrest, he noticed that the 
25 
 
defendant's eyes were bloodshot, there was a heavy odor of 
alcohol coming from his breath, and he had difficulty speaking.  
Id.  Before Dawes arrived, he had spoken with witnesses who had 
seen the defendant driving well over the speed limit just before 
impact.  Id.  Although the Appeals Court concluded that the 
information Coyle had on his own supported an inference of 
intoxication, the knowledge of Coyle and Dawes could be 
aggregated, recognizing that they "jointly participated in the 
accident investigation."  Id. at 975.  "Probable cause to arrest 
is determined upon an objective view of the facts."  Id.  
Applying the reasoning in Wooden, 13 Mass. App. Ct. at 421-422, 
the court upheld the arrest.  Rivet, supra.7 
More recently, in Commonwealth v. Roland R., 448 Mass. 278, 
285 (2007), the court applied the collective knowledge doctrine 
to a set of facts highlighting its importance.  The juvenile, 
entering a court house, placed his bag through an X-ray machine 
and walked through a metal detector.  Id. at 280.  When he was 
 
7 It is unclear whether the officers' knowledge in Rivet 
would be aggregated to meet the probable cause standard under 
the court's new rule.  Were Coyle and Dawes in sufficiently 
close communications about their objective?  What precise 
information was communicated from one officer to another?  
Despite the fact that both Coyle and Dawes were on the scene 
together for at least ten minutes, it is not evident whether 
their knowledge could be aggregated any longer.  See Rivet, 30 
Mass. App. Ct. at 974.  Not only is this illogical, but it is 
inconsistent with our objective approach to search and seizure 
questions. 
26 
 
told by a court officer that his bag would be searched manually, 
he stated that he did not want his bag searched and grabbed it, 
turning to leave the building.  Id.  Officer Martinez, a police 
officer assigned to the court house on that day, approached the 
juvenile on the steps of the court house after being told what 
had occurred.  Id.  The juvenile then ran from the court house, 
as Martinez yelled for him to stop and broadcast his description 
over the radio.  Id. 
Officer Conway, who was looking out a window on the second 
floor of the court house, observed Martinez chasing the 
juvenile.  Roland R., 448 Mass. at 280.  Conway joined in the 
chase of the juvenile, along with five to ten other officers, 
without knowing why the juvenile was being pursued.  Id.  After 
several minutes of chasing the juvenile, Conway caught up with 
him and handcuffed him.  Sergeant Detective Terestre, who also 
was unaware of the reason for the pursuit, gave the juvenile 
Miranda warnings and asked him why he was running.  Id.  The 
juvenile responded that he was running due to the contents of 
the bag, and on a search of the bag, Terestre found numerous 
plastic bags of marijuana.  Id.  The juvenile was arrested.  Id. 
"[T]he fact that the officers pursuing the juvenile were 
not personally aware of the circumstances leading to the chase 
is irrelevant."  Roland R., 448 Mass. at 285.  "In determining 
whether police officers have reasonable suspicion for making a 
27 
 
stop, 'the knowledge of each officer is treated as the common 
knowledge of all officers' and must be examined to determine 
whether reasonable suspicion exists."  Id., quoting Richardson 
v. Boston, 53 Mass. App. Ct. 201, 206 (2001).8 
Roland R. illustrates the value and the practicality of 
aggregating the knowledge of officers involved in a joint 
effort.  Frequently, officers must act quickly in an emergency 
situation.  Where multiple officers are on foot chasing a 
suspect, they often do not have the luxury of communicating the 
details of their knowledge leading up to the chase, or 
"continuously" communicating regarding their shared objective.  
 
8 I respectfully disagree with Justice Wendlandt that 
Roland R. depicts facts more closely tailored to the vertical 
collective knowledge doctrine, which, as she deems it, is 
synonymous with the "fellow officer" rule.  Post at    .  
Contrast Gittens, 211 A.D.2d at 245 ("A number of cases from the 
Federal courts and other State courts, as well as a leading 
treatise, have applied the fellow officer rule, which allows, in 
essence, the imputation of knowledge from one officer to 
another, to cover any number of officers working together on a 
joint assignment despite the lack of an express communication of 
information or direction to take action").  As she implicitly 
recognizes, there was no verbal command to the acting officers 
to arrest the defendant.  Post at     (acting officer acted on 
the "non-verbal instruction to assist his fellow officers").  
See Roland R., 448 Mass. at 280.  It is true that in Roland R., 
one officer held the requisite reasonable suspicion on his own.  
Id. at 284.  It is unclear whether the acting officers were 
"directed" to stop the juvenile.  See id. at 285 (not specifying 
whether Conway or Terestre heard radio call with description, or 
whether description included directive to stop juvenile).  Even 
if Roland R. did not implicate the horizontal collective 
knowledge doctrine, it illustrates the circumstances that 
demonstrate its application. 
28 
 
A stop should not be invalidated where there are sufficient 
facts amounting to reasonable suspicion to stop a suspect simply 
because the officer who is able to catch him or her was not 
personally aware of all the information, and where that officer 
is acting collaboratively with others who do have that 
information, either in total or in part, but who did not have 
the time to repeatedly communicate with the acting officer. 
Continuing to apply the doctrine, in Commonwealth v. Quinn, 
68 Mass. App. Ct. 476, 480 (2007), the Appeals Court imputed the 
knowledge of one officer to another where they were acting in a 
cooperative effort to investigate a break-in at a gasoline 
station in the early hours of the morning.  Officers Harvey and 
Graham were the first to arrive at the gasoline station.  Id. at 
477.  Harvey observed that the front door was "smashed," and 
Graham radioed that there had been a break-in.  Id.  Both 
officers saw two fresh sets of footprints in the snow leading 
both toward and away from the gasoline station, which led to 
fresh tire tracks heading toward a nearby highway.  Id.  Harvey 
communicated this information over the radio.  Id.  Officer 
Donahue, who was advised of the break-in but did not hear the 
report of fresh tire tracks, drove south on the highway and then 
doubled back, seeing a car heading away from the gasoline 
station toward a rotary.  Id. at 478.  After radioing to the 
other officers and confirming that no cars passed their 
29 
 
location, he ultimately was able to catch up to the car and stop 
it.  Id.  Donahue observed shards of glass, a baseball bat 
covered with shards of glass, and a fresh cut on the driver's 
hand; he arrested both occupants of the car.  Id. 
The Appeals Court imputed the knowledge of Harvey regarding 
the fresh tire tracks and footprints to Donahue.  Quinn, 68 
Mass. App. Ct. at 480.  "The officers were engaged in a 
cooperative effort to investigate the break-in at the gasoline 
station, so 'it is unnecessary for the detaining officer to know 
all the information pertaining to the incident. . . .  [T]he 
knowledge of one [police officer] . . . [is] the knowledge of 
all.'"  Id. at 480-481, quoting Commonwealth v. Zirpolo, 37 
Mass. App. Ct. 307, 311 (1994).9 
Additionally, in Montoya, 464 Mass. at 576, the court 
imputed the knowledge of one officer to another in holding that 
police had probable cause to arrest the defendant.  Troopers 
Porter and Saunders were conducting surveillance in the parking 
lot of a grocery store in separate, unmarked cars.  Id. at 569.  
Porter saw a pickup truck and sedan parked with the drivers' 
windows facing each other and the drivers "hanging out of the 
 
9 Again, under the new rule, it is likely that this 
information would not be aggregated.  Was Donahue's radio 
communication regarding passing cars enough to constitute 
"continuous" communication between himself and Harvey and Graham 
in order to aggregate their knowledge?  The abstract nature of 
this new rule will make it exceedingly difficult to apply. 
30 
 
windows" and conversing.  Id.  Saunders saw the driver of the 
sedan pass something to the driver of the truck, and Saunders 
radioed this information to Porter.  Id.  Porter approached the 
truck and saw the driver inhaling a substance through a glass 
tube, and Porter informed Saunders about this observation over 
the radio.  Id.  Saunders then stopped the sedan and arrested 
the defendant, who was the driver.  Id.  The court "impute[d] 
. . . to Saunders the knowledge of the buyer's admission to 
Porter that he had just purchased the drugs, regardless of 
whether that admission was immediately communicated by police 
radio."  Id. at 576, citing Roland R., 448 Mass. at 285. 
Beyond the cases discussed supra, there are numerous other 
Massachusetts opinions in which this court or the Appeals Court 
either mentioned the collective knowledge doctrine or applied it 
in a reasonable suspicion or probable cause context, without 
relying on the content or extent of the communications between 
the officers involved or the sufficiency of the "critical" facts 
known to the acting officer.  See Commonwealth v. Gullick, 386 
Mass. 278, 283 (1982), S.C., 462 Mass. 1011 (2012) ("Troopers 
Johnson, Ellis, and Mackin were engaged in a cooperative effort 
in the investigation of this incident.  We therefore evaluate 
probable cause on the basis of the collective information of all 
the officers"); Commonwealth v. Riggins, 366 Mass. 81, 88 (1974) 
("Where a cooperative effort is involved, facts within the 
31 
 
knowledge of one police officer have been relied on to justify 
the conduct of another"); Commonwealth v. Chaisson, 358 Mass. 
587, 590 (1971) ("The police were engaged in a cooperative 
effort in radio-equipped cars.  Hence the knowledge of one 
officer is imputed to all officers"); Commonwealth v. Dyette, 87 
Mass. App. Ct. 548, 555 n.10 (2015) ("The former municipal 
police officer's knowledge of municipal trespass ordinances may 
be imputed to his fellow officers"); Commonwealth v. Perez, 80 
Mass. App. Ct. 271, 274 (2011) ("The knowledge of one officer is 
part of 'the collective information' of other officers engaged 
in the same cooperative effort" [citation omitted]); 
Commonwealth v. Kotlyarevskiy, 59 Mass. App. Ct. 240, 243 (2003) 
("Where, as here, the arresting officers are engaged in a 
cooperative effort with other officers, probable cause is 
evaluated on the basis of the collective information of all the 
officers involved"); Commonwealth v. Peters, 48 Mass. App. Ct. 
15, 18 (1999) ("These observations by [one officer], 
communicated, and even if not, imputed to [the arresting 
officer], reasonably led the officers to suspect that the 
defendant had committed a crime" [emphasis added]); Commonwealth 
v. Mendes, 46 Mass. App. Ct. 581, 589 (1999) ("The officers who 
arrested the defendant were engaged in a cooperative effort with 
the officers in the surveillance room on the ninth floor.  We 
therefore evaluate probable cause on the basis of the collective 
32 
 
information of all the officers"); Zirpolo, 37 Mass. App. Ct. at 
311 (applying collective knowledge doctrine in vertical context 
based on arrest by officer who heard radio communication 
providing probable cause); Garcia, 34 Mass. App. Ct. at 393 n.8 
("Probable cause can be based upon the collective knowledge of 
the police officers engaged in a joint effort"); Commonwealth v. 
Andrews, 34 Mass. App. Ct. 324, 327 (1993) ("collective 
knowledge of" two officers sufficient to support investigative 
stop where one officer had detailed description of suspect's 
shirt and other officer, who did not have that description, 
stopped defendant); Commonwealth v. Scott, 29 Mass. App. Ct. 
1004, 1006 (1990) ("While Officer Surridge's personal knowledge 
may not have risen to the level of probable cause, other 
officers present at the scene, also engaged in the effort to 
apprehend the suspect, possessed additional information.  
Probable cause may be based on the collective knowledge of 
police officers when they are engaged in a cooperative effort"); 
Commonwealth v. Marlborough, 21 Mass. App. Ct. 944, 945 (1985) 
("We are not concerned with the completeness of the information 
possessed by each of the officers who collaborated in the search 
and arrest.  We evaluate probable cause on the basis of the 
collective information of all the officers"); Commonwealth v. 
Carrington, 20 Mass. App. Ct. 525, 529 n.4 (1985) ("The 
Brookline, Newton and Boston officers were engaged in a 
33 
 
cooperative effort in the investigation of this incident.  When 
an arrest is made in the course of such an investigation, the 
knowledge of one police officer is attributable to all"). 
Here, the court limits the application of the collective 
knowledge doctrine in order to prevent officers from making an 
arrest "without probable cause simply because some other 
officer, somewhere, has probable cause to arrest."  Ante at    , 
quoting State v. Ochoa, 131 Ariz. 175, 177 (Ariz. Ct. App. 
1981).  The court's discussion of the concerns of jurisdictions 
that have required communication of the facts underlying 
reasonable suspicion and probable cause do not support the new 
rule enunciated here.  See ante at    .  The court cites United 
States v. Massenburg, 654 F.3d 480, 494 (4th Cir. 2011), where 
the United States Court of Appeals for the Fourth Circuit stated 
that the absence of a communication requirement could "create an 
incentive for officers to conduct searches and seizures they 
believe are likely illegal," merely "in the hopes that 
uncommunicated information existed."  See ante at    .  But the 
court fails to explain how aggregating the knowledge of officers 
working in a cooperative effort without regard to the extent or 
content of their communications or the acting officer's precise 
knowledge of critical facts, which we have done for over one-
half century, would encourage this behavior.  The court does not 
point to one case in which we have held that officers acted 
34 
 
dishonestly by trying to pool information after a stop or an 
arrest.10  Going even further, the court discusses concerns of 
"reward[ing] police officers who were acting in bad faith," 
pointing to an example of an investigatory team finding 
"sufficient probable cause or reasonable suspicion based on 
information that had been learned after the stop."  Ante at    .  
This would not occur when aggregating the knowledge of the 
officers involved in a joint effort, because the knowledge of 
the police at the time of the stop would be aggregated; 
excluding any information learned after the stop or search.  I 
find it difficult to logically reach the court's conclusion. 
I am mindful that Massachusetts has not adopted the "good 
faith" exception to the exclusionary rule for purposes of art. 
14; instead, we focus on whether violations are "substantial and 
prejudicial."  Commonwealth v. Hernandez, 456 Mass. 528, 533 
(2010).  Nonetheless, the principles underlying the exception 
illustrate why the new rule, as set out by the court, likely 
will have little to no deterrent effect.  "The primary purpose 
 
10 In Hawkins, 361 Mass. at 386, the court declined to apply 
the collective knowledge doctrine because the arresting officers 
were not engaged in a cooperative effort with those who had 
knowledge that the recovered bonds were stolen.  Even there, the 
arresting officers "admitted they had no actual knowledge that 
the bonds had been stolen until after investigating their 
ownership," foreclosing the argument that they were acting in 
"bad faith."  Id.  The court recognized that "[t]he officers 
here undoubtedly proceeded upon an honest belief that they were 
acting within the law."  Id. at 387. 
35 
 
of the exclusionary rule is to deter future police misconduct by 
barring, in a current prosecution, the admission of evidence 
that the police have obtained in violation of rights protected 
by the Federal and State Constitutions."  Commonwealth v. 
Santiago, 470 Mass. 574, 578 (2015).  "The interest in deterring 
unlawful police conduct, which is the foundation of the 
exclusionary rule," is not implicated where an officer's conduct 
is devoid of wrongdoing.  Commonwealth v. Wilkerson, 436 Mass. 
137, 142 (2002), quoting United States v. Janis, 428 U.S. 433, 
454 (1976) (where "exclusionary rule does not result in 
appreciable deterrence, then, clearly, its use . . . is 
unwarranted"). 
The typical officer is acting in good faith, quickly, and 
in concert with his fellow officers.  Requiring the officer to 
pause to assess the state of his knowledge in such circumstances 
or to assess the level and content of his communication with his 
fellow officers is an unrealistic, ineffective, and onerous 
burden.  Moreover, where exclusion has no deterrent effect, 
"admission of the evidence is unlikely to encourage violations 
of the Fourth Amendment."  Janis, 428 U.S. at 458 n.35.  See 
United States v. Ragsdale, 470 F.2d 24, 31 (5th Cir. 1972) 
("Unless we were to presume the unlikely possibility that an 
officer would be encouraged to conduct an unlawful search on the 
faint hope that his partner possessed probable cause, no proper 
36 
 
purpose of [the exclusionary] rule would be served by denying to 
justice the truth which this search disclosed").11 
Even accepting that the new rule deters some police 
misconduct, "it is apparent as a matter of logic that there is 
little if any deterrence when the rule is invoked to suppress 
evidence obtained by an officer acting in the reasonable belief 
that his conduct did not violate" constitutional protections.  
Illinois v. Gates, 462 U.S. 213, 260 (1983) (White, J., 
concurring). 
"The deterrent purpose of the exclusionary rule necessarily 
assumes that the police have engaged in willful, or at the 
very least negligent, conduct which has deprived the 
defendant of some right.  By refusing to admit evidence 
gained as a result of such conduct, the courts hope to 
instill in those particular investigating officers, or in 
their future counterparts, a greater degree of care toward 
the rights of an accused.  Where the official action was 
pursued in complete good faith, however, the deterrence 
rationale loses much of its force." 
 
United States v. Peltier, 422 U.S. 531, 539 (1975), quoting 
Michigan v. Tucker, 417 U.S. 433, 447 (1974).  See, e.g., Brown 
 
11 Where officers are frequently uninformed of a judge's 
decision or legal basis for granting a motion to suppress, the 
"'deterrent safeguard' that is supposed to be provided by . . . 
review of probable cause is imperfect."  LaFave, supra at 
§ 3.1(d), quoting Mapp v. Ohio, 367 U.S. 643 (1961).  
"Obviously, police cannot be affirmatively influenced to change 
their methods of law enforcement by the exclusion of evidence 
when there is no communication to them of why the decision was 
made."  LaFave, supra, quoting LaFave & Remington, Controlling 
the Police:  The Judge's Role in Making and Reviewing Law 
Enforcement Decisions, 63 Mich. L. Rev. 987, 1005 (1965).  The 
prosecutor is in the best position to communicate this to an 
officer. 
37 
 
v. Illinois, 422 U.S. 590, 610 (1975) (Powell, J., concurring) 
("police normally will not make an illegal arrest in the hope of 
eventually obtaining such a truly volunteered statement").  
Maintaining the collective knowledge doctrine as we have 
historically applied it will not encourage officers to act 
without the requisite suspicion, where, as here, the acting 
officer reasonably believes that he has sufficient information 
to stop a suspect.  For these reasons, the court is incorrect 
that my approach would invite "post hoc rationalizations."  Ante 
at    . 
The court's decision today overturns years of consistent 
and settled case law within Massachusetts.  Contrast 
Commonwealth v. Rossetti, 489 Mass. 589, 609 (2022) ("Where our 
. . . jurisprudence does not currently reveal any settled or 
consistent legal principles surrounding [the issue], we view our 
decision today as departing only minimally from the principle of 
stare decisis").  Because I think our steadfast application of 
the collective knowledge doctrine to officers engaged in a 
collaborative investigation is consistent with the protections 
of art. 14, I would not do so. 
Putting aside my agreement with the court that there was 
reasonable suspicion to stop the defendant without resorting to 
the collective knowledge doctrine, applying the doctrine as it 
has been applied historically, Lieutenant (then Sergeant) Daryl 
38 
 
Dwan's and Officer Luis Lopez's knowledge and observations would 
be imputed to Doherty.  All three officers were working as part 
of a joint effort to apprehend the perpetrator of the armed 
robbery that had occurred minutes prior.  Doherty was listening 
to the department radio channel, the same station on which the 
description including the beard was broadcast, on which he heard 
Dwan's updates about his observations on Morrissey Boulevard.  
After hearing that, Doherty decided to canvas the Clam Point 
area to search for the suspect.  As soon as details of the armed 
robbery were broadcast via the radio channel, Dwan began 
canvassing Morrissey Boulevard.  When Lopez heard the broadcast 
reporting the armed robbery, he began driving around the area of 
Victory Road, which he believed to be a potential flight path of 
the suspect.  Eventually, Dwan noticed the defendant, and 
approached him at the same time as Doherty.  Dwan described the 
seizure and search of the defendant's backpack as a "joint 
endeavor." 
As the court concedes, ante at    , the three officers were 
engaged in a joint effort, sparked by communications on the 
department radio channel, to discover the suspect.  Thus, "'the 
knowledge of each officer is treated as the common knowledge of 
all officers' and must be examined to determine whether 
reasonable suspicion exists."  Roland R., 448 Mass. at 285, 
quoting Richardson, 53 Mass. App. Ct. at 206.  Applying the 
39 
 
collective knowledge doctrine as it should be applied, in my 
view, further bolsters reasonable suspicion. 
Inserting a requirement that the officers be in "close and 
continuous" communications with each other about a joint 
objective and that the acting officer must have knowledge of at 
least some of the critical facts eviscerates the horizontal 
collective knowledge doctrine as it has been applied by 
Massachusetts courts for over one-half century and replaces it 
with a convoluted test that is problematic in its application.  
Because I think that our jurisprudence regarding the collective 
knowledge doctrine is supported by the general objectivity with 
which we approach search and seizure law under art. 14, and by 
practical considerations, I would not upend it. 
 
I concur with the court's finding of reasonable suspicion, 
but I respectfully dissent from the decision of the court 
regarding the retreat from the collective knowledge doctrine. 
 
 
WENDLANDT, J. (concurring).  We are called in this case, as 
the United States Supreme Court was called in Terry v. Ohio, 392 
U.S. 1, 4 (1968), to address "serious questions concerning the 
role of the Fourth Amendment [to the United States Constitution 
and art. 14 of the Massachusetts Declaration of Rights] in the 
confrontation on the street between a[n individual] and the 
police[ officer] investigating suspicious circumstances."  In 
Terry, the Court carved "a narrowly drawn authority" to permit 
an officer to conduct a limited stop and patfrisk of an 
individual based on reasonable suspicion -- a showing less than 
that required to establish probable cause for a warrant.  Id. at 
27.  This strictly circumscribed permission was designed to give 
the officer on the scene "an escalating set of flexible 
responses, graduated in relation to the amount of information" 
possessed by the officer, during the "rapidly unfolding and 
often dangerous situations" the officer faces, especially in the 
nation's cities.  Id. at 10. 
 
In detailing this narrow ground for a stop, the Court 
emphatically rejected the notion that the stop did not implicate 
core constitutional concerns; "[i]t must be recognized that 
whenever a police officer accosts an individual and restrains 
his freedom to walk away, he has 'seized' that person" in a 
constitutional sense.  Id. at 16.  A stop and subsequent 
patfrisk of an individual "is a serious intrusion upon the 
2 
 
 
 
sanctity of the person, which may inflict great indignity and 
arouse strong resentment, and it is not to be undertaken 
lightly."  Id. at 17.  Nonetheless, the Court recognized the 
need to provide a level of flexibility to police activities, 
which entail "necessarily swift action predicated upon the on-
the-spot observations of the officer on the beat" (emphasis 
added).  Id. at 20. 
 
Balancing the nature of the invasion and the needs of law 
enforcement officers to act upon the information they are 
receiving in real time, the Court set forth the following 
objective test to permit a warrantless stop:  whether "the facts 
available to the officer at the moment of the seizure . . . 
[would] 'warrant a [person] of reasonable caution in the 
belief'" that a crime had been, was being, or was about to be 
committed (emphasis added).  Id. at 21-22.  In defining the 
reasonable suspicion test, the Court noted that "[a]nything less 
would invite intrusions upon constitutionally guaranteed rights 
based on nothing more substantial than inarticulate hunches" 
(emphasis added); and it remarked that a test based on good 
faith alone would subject the people to the discretion of the 
police, largely causing the constitutional protections to 
"evaporate."  Id. at 22.  The genesis of this narrow police 
authorization and the balance upon which it rests counsel that 
3 
 
 
 
we reject the so-called horizontal collective knowledge doctrine 
in all its varied forms. 
 
The court today charts a different path, and there is some 
good news and some bad.  First, the good news:  the court 
rejects what it terms the "minority view" of the "horizontal 
collective knowledge doctrine."  Ante at    .  Under this legal 
regime, the officer on the beat who detains you, pats you down, 
and invades your personal autonomy by sliding hands up, down and 
across your body in an ostensible search for weapons is not 
considered to be acting as an individual human being.  Instead, 
the officer is part of "the" police -- a conceptual collective 
"organism" apparently composed of a database of inculpatory 
information about which the individual officer is entirely 
ignorant at the time he or she stops and frisks you.  The 
officer's conduct is justified if somewhere in the dark recesses 
of "the" police databank there exists information that can be 
cobbled together post hoc to form the bare minimal showing 
required for reasonable suspicion.  The court rightly rejects 
this police encounter of the third kind, and that is good news. 
 
Now, the bad news:  the court adopts what it terms the 
"second approach" of the "horizontal collective knowledge" 
doctrine.  Ante at    .  Under this new order, the individual 
officer is not part of a faceless, amorphous collective.  
Instead, he or she is part of a "team" -- a finite set of 
4 
 
 
 
officers "in close and continuous communication" with a "shared 
objective."  Ante at    .  The court adopts this version of the 
horizontal collective knowledge doctrine, reasoning that, 
despite all the advances in communications and surveillance 
technology since Terry was decided, officers who are working as 
a team on a shared mission and who are in constant contact 
apparently can communicate "critical" facts but cannot be 
expected to communicate the minimal information required for 
reasonable suspicion.  The stop and patfrisk are justified after 
the fact if the facts constituting reasonable suspicion, while 
uncommunicated, were known to one or more of the officers on the 
team –- in short, an officer on the beat can detain and pat 
frisk you based on a hunch, in the hopes that afterward fellow 
officers can fill in the missing gaps in the reasonable 
suspicion calculus. 
 
In assessing the merits of the court's approach, it is 
important to remember that reasonable suspicion is, by design, 
not a high hurdle; it is something less than probable cause.  It 
can be based on information as to which the acting officer has 
personal knowledge -- information based on the officer's own 
observations gathered through the use of his or her own senses.  
It can also be grounded in information acquired from third 
parties or other sources of reliable information, whether from 
911 calls, police dispatchers, police bulletins, confidential 
5 
 
 
 
informants, or fellow officers.  And the acting officer may draw 
reasonable inferences and pull on his or her years of experience 
in assessing the evolving situation. 
 
Holding a law enforcement officer to this bare minimal 
standard even when he or she is working jointly with others 
before permitting the officer to intrude on the sanctity of the 
person does not ignore, as the court surmises, the "practical 
reality of effective law enforcement."  Ante at    .  Indeed, it 
was the recognition of the realities of fast-paced, on the 
street encounters that was the genesis of the reasonable 
suspicion standard -– a standard that represents the Court's 
careful calibration between the nature of the invasion of the 
rights of the individual, on the one hand, and the undeniable 
needs of law enforcement to urgently respond to suspected 
criminal activity and potentially dangerous situations, on the 
other.  The Court in Terry set a constitutional floor –- a 
baseline that we certainly should not (and in my view cannot) 
abandon under the auspices of art. 14 of our State Constitution. 
 
1.  Fellow officer rule.  Notably, this case does not 
concern the fellow officer rule, what the court terms the 
"vertical" collective knowledge doctrine.  Under this rule, the 
acting officer may assist a fellow officer by executing a Terry-
type stop in reliance that the directing officer had a 
constitutional basis for the stop; in such a case, whether the 
6 
 
 
 
stop passes constitutional muster will depend on whether the 
directing officer had the information constituting reasonable 
suspicion.  See United States v. Hensley, 469 U.S. 221, 231 
(1985), quoting United States v. Robinson, 536 F.2d 1298, 1299 
(9th Cir. 1976) ("effective law enforcement cannot be conducted 
unless police officers can act on directions and information 
transmitted by one officer to another and . . . officers, who 
must often act swiftly, cannot be expected to cross-examine 
their fellow officers about the foundation for the transmitted 
information"); Whiteley v. Warden, Wyo. State Penitentiary, 401 
U.S. 560, 568 (1971) ("police officers called upon to aid other 
officers in executing arrest warrants are entitled to assume 
that the officers requesting aid offered the magistrate the 
information requisite to support an independent judicial 
assessment of probable cause"). 
 
The fellow officer rule is "a matter of common sense:  the 
rule minimizes the volume of information concerning suspects 
that must be transmitted to other jurisdictions or officers and 
enables police to act promptly in reliance on information from 
another jurisdiction or officer" (alterations omitted).  United 
States v. Massenburg, 654 F.3d 480, 494 (4th Cir. 2011), quoting 
Hensley, 469 U.S. at 231.  Thus, the fellow officer rule "simply 
directs us to substitute the knowledge of the instructing 
officer or officers for the knowledge of the acting officer."  
7 
 
 
 
Massenburg, supra at 493.  See 2 W.R. LaFave, Search and Seizure 
§ 3.5(b), at 333 (6th ed. 2020) ("Thus, under the Whiteley rule 
[or, as it is sometimes termed, the 'fellow officer' rule] 
police are in a limited sense 'entitled to act' upon the 
strength of a communication through official channels directing 
or requesting than an arrest or search be made" [citations 
omitted]).1 
 
2.  Horizontal collective knowledge doctrine.  Unlike the 
fellow officer rule, which is a commonsense response to the 
oftentimes quickly unfolding events officers encounter and 
allows the acting officer to rely on the verbal (or nonverbal, 
see note 1, supra) directions relayed by fellow officers, the 
horizontal collective knowledge doctrine is anathema to the 
Fourth Amendment and art. 14.  Even under the version of the 
"second approach" to the horizontal collective knowledge 
doctrine adopted by the court, it permits an officer to stop 
(and presumably pat frisk) an individual without beforehand 
 
 
1 In Commonwealth v. Roland R., 448 Mass. 278, 280 (2007), 
for example, the acting officer stopped the juvenile after 
seeing fellow officers chasing him at the direction of an 
instructing officer, who had the requisite information 
constituting reasonable suspicion.  Although the court stated 
that its conclusion rested on the horizontal collective 
knowledge doctrine, id. at 285, the facts fall within the fellow 
officer rule -- namely, that the acting officer acted upon 
seeing the chase, a nonverbal instruction to assist his fellow 
officers, who were chasing the juvenile at the order of the 
directing officer who, in turn, had the requisite reasonable 
suspicion.  Id. at 280. 
8 
 
 
 
having information constituting reasonable suspicion and without 
any commonsense reliance on a fellow officer's directions; 
shockingly, it invites a judge to be complicit in the unraveling 
of this fundamental constitutional right.  See Terry, 392 U.S. 
at 9, quoting Union Pac. Ry. Co. v. Botsford, 141 U.S. 250, 251 
(1891) ("No right is held more sacred, or is more carefully 
guarded, by the common law, than the right of every individual 
to the possession and control of his own person, free from all 
restraint or interference of others, unless by clear and 
unquestionable authority of law"). 
 
The doctrine rests on the hope that, post hoc, a judge will 
cobble together information known to other officers on the team 
-- information as to which the acting officer is entirely 
ignorant and has no basis to believe is known to a fellow 
officer -- to constitute the minimal requirement of reasonable 
suspicion for the stop.  It is divorced entirely from the 
urgency that birthed the limited nature of the Terry-type stop 
and frisk -– namely, that the officer at the scene, the one 
facing the exigencies attendant thereto, needs to be able to 
rely on the rapidly unfolding information known to him or her as 
well as the "reasonable inferences which [the officer] is 
entitled to draw from the facts in light of his [or her] 
experience."  Terry, 392 U.S. at 27.  And it jettisons the 
careful balance struck by the Court in defining the reasonable 
9 
 
 
 
suspicion standard, between the right to be free from 
governmental restraint and the attendant serious intrusion on 
the sanctity of the person, on the one hand, and the needs of 
the law enforcement officer on the street to be able to quickly 
react to the information being received and to draw reasonable 
inferences from that information consistent with his or her 
experience, on the other.  Id. at 21-22. 
 
The few cases that provide a rationale for adopting the 
horizontal collective knowledge doctrine sacrifice this careful 
balance apparently on the same assumption driving the court's 
decision today -- namely, that officers working as a team in 
close and continuous communication can communicate some 
"critical facts," but cannot be expected communicate the minimal 
information constituting reasonable suspicion during the course 
of the fast-paced, dynamically evolving events on the ground.  
See, e.g., United States v. Cook, 277 F.3d 82, 86 (1st Cir. 
2002) ("Investigative stops generally occur in a dynamic 
environment marked by the potential for violence.  Officers who 
jointly make such stops rarely will have an opportunity to 
confer during the course of the stop").  Contrary to this 
distorted view of the balance struck by the Supreme Court in 
Terry, adherence to the reasonable suspicion standard would not 
require officers in hot pursuit of a suspect to "stop and 
confer" or to convene a "conference" while permitting the 
10 
 
 
 
suspect to flee.  Ante at    .  Obviously, officers could employ 
any and all methods of communication, including, for example, 
those used to relay the "critical facts" constituting those 
minimally required to rise to the level of reasonable suspicion.  
But if the acting officer lacks information required for 
reasonable suspicion, the officer's conduct falls below the 
Supreme Court's carefully constructed constitutional floor -- it 
is unguided by any constitutional norms.  See United States v. 
Ross, 456 U.S. 798, 824-825 (1982), quoting Mincey v. Arizona, 
437 U.S. 385, 390 (1978) ("searches conducted outside the 
judicial process, without prior approval by judge or magistrate, 
are per se unreasonable under the Fourth Amendment -- subject 
only to a few specifically established and well-delineated 
exceptions"). 
 
Perversely, because the acting officer is totally ignorant 
as to whether information constituting reasonable suspicion 
exists, the horizontal collective knowledge doctrine provides 
incentive to the acting officer to roll the dice and stop an 
individual knowing that reasonable suspicion is absent, on the 
off chance that other information unbeknownst to him or her 
might supply the gaps missing in the reasonable suspicion 
calculus.  See Massenburg, 654 F.3d at 494 (horizontal 
collective knowledge doctrine "would only create an incentive 
for officers to conduct search and seizures they believe are 
11 
 
 
 
likely illegal," which is "directly contrary to the purposes of 
longstanding Fourth Amendment jurisprudence").  In short, the 
doctrine represents the feared "[a]nything less," which the 
Supreme Court rightly predicted "would invite intrusions upon 
constitutionally guaranteed rights based on nothing more 
substantial than inarticulate hunches."  Terry, 392 U.S. at 22. 
 
Like the United States Courts of Appeals for the Second, 
Fourth, and Tenth Circuits, I can find nothing to commend the 
doctrine and accordingly reject it.  See Massenburg, 654 F.3d at 
494-495 ("Though we have studied our sister circuits' cases 
adopting an aggregation rule, we can find no convincing defense 
of it. . . .  Because we believe the aggregation rule runs 
contrary to the Supreme Court's Fourth Amendment jurisprudence, 
would seriously erode the efficacy of the exclusionary rule's 
deterrent purposes, and serves none of the legitimate ends of 
law enforcement, we reject it").  See also United States v. 
Hussain, 835 F.3d 307, 316 n.8 (2d Cir. 2016) ("Absent record 
evidence that [the first officer] communicated his suspicion or 
any relevant information to [the acting officer] before the 
latter began to conduct the protective search, we will not 
impute his knowledge or reasonable suspicion to [the acting 
officer] under the doctrine of collective knowledge. . . .  [W]e 
decline to extend the collective knowledge doctrine to cases 
where, as here, there is no evidence that an officer has 
12 
 
 
 
communicated his suspicions with the officer conducting the 
search, even when the officers are working closely together at a 
scene"); United States v. Whitley, 680 F.3d 1227, 1234 n.3 (10th 
Cir. 2012), quoting United States v. Chavez, 534 F.3d 1338, 1345 
(10th Cir. 2008), cert. denied, 555 U.S. 1121 (2009) (confirming 
requirement that individual officers "have communicated the 
information they possess individually" to arresting officer ex 
ante); United States v. Shareef, 100 F.3d 1491, 1503-1505 (10th 
Cir. 1996) (no constitutional basis for arrest where officers 
did not actually communicate information constituting probable 
cause to one another, either verbally or nonverbally, ex ante). 
 
To be sure, like the court here, ante at    , two of these 
Federal courts -- the Second and Tenth Circuits -- themselves 
use the "collective knowledge" language such as "imputed" or 
"aggregated" information in describing their approach; it is an 
unfortunate misuse of the terminology.  Instead, the courts in 
these jurisdictions conclude that the acting officer may rely on 
information communicated to him or her by other officers or 
sources and that he or she need not have personally observed the 
information; but the acting officer must have had this 
information, whether from his or her direct observations or from 
what had been communicated to him or her, ex ante, before the 
stop and patfrisk were initiated.  See Hussain, 835 F.3d at 316 
n.8; Chavez, 534 F.3d at 1345. 
13 
 
 
 
 
In other words, the rules of evidence, which generally 
limit a witness to testifying to information as to which he or 
she has personal knowledge, and which traditionally govern 
admissibility of evidence in our court rooms, do not limit the 
scope of the information an officer on the beat may rely upon in 
assessing the rapidly unfolding situation he or she encounters 
on the street.  See, e.g., Commonwealth v. Manha, 479 Mass. 44, 
47-48 (2018) (reasonable suspicion to conduct Terry-type stop 
and patfrisk based on reliable information from anonymous 911 
caller but as to which acting officer lacked personal 
knowledge); Commonwealth v. Mercado, 422 Mass. 367, 369 (1996) 
(reasonable suspicion to conduct Terry-type stop based, in part, 
on information conveyed in radio bulletin and by witness but as 
to which officer lacked personal knowledge).  See also United 
States v. Blair, 524 F.3d 740, 751 (6th Cir. 2008) (noting 
"unremarkable proposition that one officer may conduct a Terry[-
type] stop based on the information obtained from another 
officer").  Because those evidentiary rules do not govern the 
reasonable suspicion analysis, I see no need to adopt any 
version of the horizontal collective knowledge doctrine on the 
basis of their application.  See Terry, 392 U.S. at 21-22 
(officer may rely on facts sufficient to "warrant a man of 
reasonable caution in the belief" that crime had been, was 
being, or was about to be committed). 
14 
 
 
 
 
Indeed, the Cartesian terminology, in my view, is entirely 
unhelpful and has led to widespread confusion.  See ante 
at     (describing "vertical" collective knowledge doctrine; 
"first approach" to horizontal collective knowledge doctrine 
requiring ex ante communication of facts constituting reasonable 
suspicion to acting officer; exception to first approach; 
"second approach" to horizontal collective knowledge doctrine; 
"minority view" of horizontal collective knowledge doctrine; and 
numerous other variations thereof). 
 
The rule should be, and under Terry must be, this:  one 
officer, whether it is the officer who directs the acting 
officer to stop the suspect (i.e., the fellow officer rule, see 
discussion and note 1, supra) or the acting officer him- or 
herself, must have the information constituting reasonable 
suspicion -- whether it is information as to which the officer 
has personal knowledge or information he or she has been told -- 
before the stop and patfrisk are conducted.  This is the 
constitutional balance struck by Terry and its progeny between 
the rights of the individual to be free from unreasonable 
searches and seizures and the need to accommodate the law 
enforcement realities of the quickly unfolding events on the 
ground. 
 
Laudably, the court rejects the more extreme version of the 
horizontal collective knowledge doctrine, which treats the 
15 
 
 
 
police as an "organism" with unfettered access to a database of 
inculpatory information that can be accessed post hoc to justify 
an otherwise unconstitutional stop and patfrisk.  See Shareef, 
100 F.3d at 1504 & n.6.  The court today cabins its version of 
the horizontal collective knowledge doctrine, concluding that it 
applies only in situations where officers are involved in a 
joint investigation with a mutual purpose and objective and in 
close and continuous communication with each other about that 
objective, and the acting officer has knowledge "of at least 
some of the critical facts."  Ante at    .  But the court does 
not explain why an officer who knows the "critical" facts cannot 
be expected to know the facts constituting reasonable suspicion, 
which itself is a low bar.  See generally 4 LaFave, supra at 
§ 9.5(b) at 672-691 (comparing reasonable suspicion and probable 
cause).  Although to a lesser extent than the unbridled adoption 
of the "minority view" of the horizontal collective knowledge 
doctrine might be, the adopted approach is the proverbial 
camel's nose under the tent.  It threatens individuals with 
unconstitutional intrusions on their persons, inflicting great 
indignity and arousing strong resentment, all the while 
requiring judges to condone this behavior in connection with 
their hindsight review. 
 
3.  Inevitable discovery exception.  The court adopts its 
version of the horizontal collective knowledge doctrine 
16 
 
 
 
apparently out of the concern that rejecting the horizontal 
collective knowledge doctrine would "make[] little sense from a 
practical standpoint" because it would "[b]as[e] the legitimacy 
of the stop solely on what the officer who first approaches the 
suspect knows."  Ante at    , quoting Cook, 277 F.3d at 86.  
However, if the first officer acts too swiftly but a second 
officer has reasonable suspicion, our existing inevitable 
discovery doctrine permits the use of the evidence at trial as 
an exception to the exclusionary rule.  See United States v. 
Ragsdale, 470 F.2d 24, 30 (5th Cir. 1972) (exclusionary rule 
does not apply when search "would imminently and lawfully have 
been made and [the evidence would have been] discovered at this 
very time and place and by this team of officers" if acting 
officer had waited); United States v. Gorham, 317 F. Supp. 3d 
459, 474 (D.D.C. 2018), quoting 2 W.R. LaFave, Search and 
Seizure § 3.5(c) (5th ed. Supp. Oct. 2017) ("Unlike in the 
typical 'horizontal' collective knowledge case, Ragsdale does 
not require a post hoc aggregation of information among 
officers; rather, an officer with all the required information 
was present and 'it is clear the search would imminently and 
lawfully have been made'"). 
 
Under this long-standing doctrine: 
"if the government can prove that the evidence would have 
been obtained inevitably and, therefore, would have been 
admitted regardless of any overreaching by the police, 
17 
 
 
 
there is no rational basis to keep that evidence from the 
jury in order to ensure the fairness of the trial 
proceedings.  In that situation, the State has gained no 
advantage at trial and the defendant has suffered no 
prejudice.  Indeed, suppression of the evidence would 
operate to undermine the adversary system by putting the 
State in a worse position than it would have occupied 
without any police misconduct." 
 
Nix v. Williams, 467 U.S. 431, 447 (1984).  See id. at 448-449 
(declining to apply exclusionary rule when "volunteer search 
party would ultimately or inevitably have discovered the 
victim's body").  The doctrine provides that evidence that would 
otherwise have been excluded is admissible nonetheless if the 
Commonwealth demonstrates by a preponderance of the evidence 
"that discovery of the evidence by lawful means was certain as a 
practical matter, 'the officers did not act in bad faith to 
accelerate the discovery of evidence, and the particular 
constitutional violation is not so severe as to require 
suppression.'"  Commonwealth v. Hernandez, 473 Mass. 379, 386 
(2015), quoting Commonwealth v. Sbordone, 424 Mass. 802, 810 
(1997) (no exclusion of handgun found in course of unlawful 
search of trunk because there would have been reasonable 
suspicion after subsequent showup identification).  Thus, our 
long-standing jurisprudence based on the inevitable discovery 
doctrine provides a commonsense approach to assuage the fear 
18 
 
 
 
undergirding the court's adoption of its version of the 
horizontal collective knowledge doctrine.2 
 
4.  Reasonable suspicion.  Despite the foregoing, I concur 
in the judgment because Officer Brian Doherty had the requisite 
reasonable suspicion; I do so, however, without imputing any of 
Lieutenant (then Sergeant) Daryl Dwan's uncommunicated 
information.  In other words, Doherty, even without the 
information concerning the suspect's facial hair, had reasonable 
suspicion to stop the defendant. 
 
Briefly, at the time Doherty stopped the defendant, he knew 
that an armed robbery had been committed a little after 
3:30 A.M.  The grave nature of the crime and the imminent danger 
presented by the suspect on the loose in the neighborhood 
properly may be considered in the reasonable suspicion calculus.  
See Commonwealth v. Henley, 488 Mass. 95, 104 (2021), quoting 
Commonwealth v. Depina, 456 Mass. 238, 247 (2010) ("The gravity 
of the crime and the present danger of the circumstances may be 
considered in the reasonable suspicion calculus"); Commonwealth 
 
2 Of course, as the court notes, ante at    , the inevitable 
discovery doctrine may not apply where a second officer both has 
been unable to communicate information to the acting officer and 
is not at the scene of the stop and patfrisk.  In such a 
scenario, the acting officer lacks reasonable suspicion; we 
ought not permit him or her to get by the meager constitutional 
hurdle -- the one set by the Supreme Court in Terry as the 
constitutionally mandated minimal standard -- with a little help 
from his or her silent and distant friends. 
19 
 
 
 
v. Evelyn, 485 Mass. 691, 705 (2020) ("circumstances indicated a 
potential ongoing risk to public safety and therefore weighed in 
favor of reasonable suspicion"). 
 
Doherty also had, at a minimum, heard the first transmitted 
description of the suspect of the armed robbery as a Black man 
in his late twenties, who was between five foot seven and five 
foot eight, wearing jeans, and walking toward a pharmacy, and 
then had seen that the defendant largely matched this 
description.  See Commonwealth v. Meneus, 476 Mass. 231, 236 
(2017), quoting Commonwealth v. Lopes, 455 Mass. 147, 158 (2009) 
("We have no hard and fast rule governing the required level of 
particularity of a description; our constitutional analysis 
ultimately is practical, balancing the risk that an innocent 
person will be needlessly stopped with the risk that a guilty 
person will be allowed to escape" [alterations omitted]). 
 
Doherty also saw the defendant in close temporal and 
geographic proximity to the scene of the armed robbery, which 
had occurred just seven minutes prior to him encountering the 
defendant.  See Commonwealth v. Warren, 475 Mass. 530, 536 
(2016) ("proximity of the stop to the time and location of the 
crime is a relevant factor in the reasonable suspicion 
analysis"). 
 
It was dark and raining, and Doherty did not see anyone 
else in the area surrounding the crime scene as he canvassed 
20 
 
 
 
various streets in the area for approximately four to six 
minutes following the report of the crime.  He was aware of 
Dwan's report that Dwan was on Morrisey Boulevard and also had 
not seen anyone.  Thus, not only did the defendant fit the 
general description of the suspect, but the defendant was the 
only person near the scene of the crime within seven minutes of 
its occurrence.  See Evelyn, 485 Mass. at 704-705 (reasonable 
suspicion without any description when "officers encountered the 
defendant thirteen minutes after the shooting, one-half mile 
distant from it" on "a cold night, and the officers had not seen 
any other pedestrians on the nearby streets").  Compare Warren, 
475 Mass. at 536 (no reasonable suspicion based on general 
description for defendant found twenty-five minutes later, 
approximately one mile from scene of crime), with Henley, 488 
Mass. at 104 (reasonable suspicion based on general description 
for defendant found five minutes later, two blocks from scene of 
crime), and Depina, 456 Mass. at 246 (reasonable suspicion based 
on general description when defendant, "approximately ten 
minutes after the report of the shooting, was seen within three 
blocks of the crime scene, and he was moving away from the area 
of the shooting").  See also Warren, supra, citing Commonwealth 
v. Doocey, 56 Mass. App. Ct. 550, 555 n.8 (2002) ("Proximity is 
accorded greater probative value in the reasonable suspicion 
calculus when the distance is short and the timing is close"). 
21 
 
 
 
 
Finally, Doherty knew that the defendant was in the 
reported flight path of the suspect and that that path included 
a hole in the fence between the crime scene and the location 
where he found the defendant.  See Warren, 457 Mass. at 536-538, 
citing Commonwealth v. Foster, 48 Mass. App. Ct. 671, 672-673, 
676 (2000) (whether defendant is found in direction of flight 
path relevant to reasonable suspicion). 
 
Considering the totality of the circumstances,3 it was 
reasonable for Doherty to stop the defendant.  Accordingly, I 
concur in the judgment. 
 
 
3 Even if no one factor results in the necessary 
individualized suspicion, considered in combination, several 
factors "may allow the police to narrow the range of suspects to 
[a] particular individual[]."  Mercado, 422 Mass. at 371.  See 
id. (circumstances giving rise to reasonable suspicion must be 
such as to "distinguish [the defendant] from other persons in 
the vicinity").