Case Title: Commonwealth v. Perry

Citation: 

Docket Number: SJC-13144

State: massachusetts

Court: Massachusetts Supreme Court

Date: 2022-04-01T00:00:00Z

Document:
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SJC-13144 
 
COMMONWEALTH  vs.  JERRON PERRY. 
 
 
 
Suffolk.     December 8, 2021. - April 1, 2022. 
 
Present:  Budd, C.J., Gaziano, Lowy, Cypher, Kafker, Wendlandt, 
& Georges, JJ. 
 
 
Cellular Telephone.  Constitutional Law, Search and seizure, 
Privacy, Probable cause, Retroactivity of judicial holding.  
Search and Seizure, Expectation of privacy, Warrant, 
Affidavit, Probable cause.  Privacy.  Probable Cause.  
Practice, Criminal, Motion to suppress, Warrant, Affidavit, 
Retroactivity of judicial holding.  Retroactivity of 
Judicial Holding. 
 
 
 
Indictments found and returned in the Superior Court 
Department on July 12, 2019. 
 
A pretrial motion to suppress evidence was heard by Robert 
L. Ullmann, J. 
 
An application for leave to prosecute an interlocutory 
appeal was allowed by Georges, J., in the Supreme Judicial Court 
for the county of Suffolk, and the case was reported by him. 
 
 
Eric Tennen for the defendant. 
Cailin M. Campbell, Assistant District Attorney (Jennifer 
J. Hickman, Assistant District Attorney, also present) for the 
Commonwealth. 
Mason A. Kortz, for Surveillance Technology Oversight 
Project, amicus curiae, submitted a brief. 
2 
 
Brett Max Kaufman, Ashley Gorski, & Patrick Toomey, of New 
York, Jennifer Granick, Jennifer Lynch, & Andrew Crocker, of 
California, Matthew Spurlock, Committee for Public Counsel 
Services, Matthew R. Segal, Jessie J. Rossman, Jessica J. Lewis, 
Nathan Freed Wessler, & Joshua M. Daniels, for American Civil 
Liberties Union & others, amici curiae, submitted a brief. 
 
 
 
GAZIANO, J.  As law enforcement capabilities continue to 
develop in the wake of advancing technology, so too must our 
constitutional jurisprudence.  To this end, we must grapple with 
the constitutional implications of "tower dumps," a relatively 
novel law enforcement tool that provides investigators with the 
cell site location information (CSLI) for all devices that 
connected to specific cell towers during a particular time 
frame. 
 
Here, the Commonwealth obtained search warrants for seven 
tower dumps,1 corresponding to the locations of six robberies and 
an attempted robbery that resulted in a homicide, all of which 
investigators believed to have been committed by the same 
individual.  After analyzing the information contained in the 
tower dumps, investigators determined that the defendant had 
been near the scenes of two of the crimes.  The defendant 
subsequently was charged with the robberies and the homicide, 
and he moved to suppress all evidence obtained from the tower 
 
1 As is customary, each single tower dump included 
information from multiple cell towers operated by different 
cellular service providers.  See discussion, infra. 
3 
 
dumps as the fruits of an unconstitutional search.  A Superior 
Court judge denied the motion, and the defendant filed an 
application in the county court seeking leave to pursue an 
interlocutory appeal; the single justice reserved and reported 
the case to the full court. 
 
The defendant argues that the Commonwealth's use of the 
tower dumps intruded upon his reasonable expectation of privacy, 
and therefore effectuated a search under the Federal and State 
Constitutions.  He also contends that search warrants for tower 
dumps are per se unconstitutional because they necessarily lack 
particularity.  In addition, the defendant asserts that, here, 
the warrants were not supported by probable cause. 
 
We agree that the government's use of the seven tower dumps 
was an intrusion upon the defendant's reasonable expectation of 
privacy, and therefore constituted a search under art. 14 of the 
Massachusetts Declaration of Rights.  We do not agree, however, 
that warrants for tower dumps are per se unconstitutional.  
Accordingly, investigators may use tower dumps so long as they 
comply with the warrant requirements of art. 14. 
 
Here, the second of the two search warrants was 
sufficiently particular and supported by probable cause, and 
therefore the use of the information obtained from it does not 
offend the Massachusetts Declaration of Rights.  The first 
warrant, however, was not supported by probable cause, and 
4 
 
accordingly, any evidence obtained as a result of it must be 
suppressed.2 
 
1.  Background.  a.  CSLI and tower dumps.  An overview of 
the technology at issue is necessary to a discussion of the 
issues in this case.  Cellular telephones "make calls, send text 
messages and emails, and access the internet by connecting to a 
set of radio antennas called 'cell sites'" (quotation and 
citation omitted).  United States v. Thorne, 548 F. Supp. 3d 70, 
113 (D.D.C. 2021).  See Carpenter v. United States, 138 S. Ct. 
2206, 2211 (2018).  To receive cellular service, "a cellular 
telephone will connect to the cell site which provides the 
strongest signal, typically, albeit not always, the nearest 
one."  Commonwealth v. Jones, 477 Mass. 307, 313 n.11 (2017).  
"The typical cell site covers a more-or-less circular geographic 
area," with "three (or sometimes six) separate antennas pointing 
in different directions" which divide the site's radius into 
smaller, wedge-shaped sectors.  Carpenter, supra at 2225 
(Kennedy, J., dissenting). 
 
2 We acknowledge the amicus briefs submitted by the 
Surveillance Technology Oversight Project and by the American 
Civil Liberties Union, the American Civil Liberties Union of 
Massachusetts, Inc., the Committee for Public Counsel Services, 
the Electronic Frontier Foundation, and the Massachusetts 
Association of Criminal Defense Lawyers in support of the 
defendant. 
5 
 
 
Once a cellular telephone connects with a cell site (either 
to send or receive communications), the site will "generate[] a 
time-stamped record known as [CSLI]."3  Id. at 2211.  Among other 
information, this record contains the precise location of the 
cell site, as well the specific sectors that provided service to 
the cellular telephone.  See Commonwealth v. Augustine, 467 
Mass. 230, 237-238 (2014), S.C., 470 Mass. 837 and 472 Mass. 448 
(2015) (Augustine I).  When a cellular telephone establishes a 
connection with a particular sector of a cell site, it can be 
inferred that the user was located within that sector's range of 
service, or "coverage area," at the time of the connection.  
Commonwealth v. Wilkerson, 486 Mass. 159, 174 (2020).  Service 
providers retain CSLI for their own business purposes, such as 
finding weak areas of their network, but it also has proved 
useful to law enforcement in order to approximate an 
individual's location at a given time.  Carpenter, 138 S. Ct. 
at 2212. 
 
3 There are two forms of CSLI.  See Commonwealth v. 
Augustine, 467 Mass. 230, 238 & n.18 (2014), S.C., 470 Mass. 837 
and 472 Mass. 448 (2015) (Augustine I).  Telephone call CSLI is 
generated only when a cellular telephone uses cell service, such 
as by placing or receiving a call or a text message.  Id. 
at 238.  Registration CSLI, by contrast, is created without any 
action by the user, as cellular telephones "regularly identify 
themselves to the nearest cell site with the strongest signal, 
through a process known as 'registration.'"  Id. at 238 n.18.  
Only telephone call CSLI is at issue here. 
6 
 
 
The precision with which police are able to approximate an 
individual's location varies significantly.  Some CSLI only 
enables investigators to place an individual within "an area 
miles in diameter," whereas other CSLI allows investigators to 
"calculate users' locations with precision that approaches that 
of GPS.[4]"  ECPA Reform and the Revolution in Location Based 
Technologies and Services:  Hearing Before the Subcomm. on the 
Constitution, Civil Rights, and Civil Liberties of the H. Comm. 
on the Judiciary, 111th Cong., at 23, 25 (2010) (testimony of 
Professor Matt Blaze) (Blaze Testimony I).  The degree of 
precision largely depends on the size of the sector's coverage 
area and the technology in use.  See id. at 25.  The size of the 
coverage area, in turn, depends on the number of nearby cell 
sites; "[t]he greater the concentration of cell sites, the 
smaller the coverage area."  Carpenter, 138 S. Ct. at 2211.  "As 
cellular telephone use has grown, cellular service providers 
have responded by adding new cell sites to accommodate 
additional customers," resulting in increasingly precise CSLI.  
See Augustine I, 467 Mass. at 239. 
 
CSLI also is more precise if the cell site uses newer, more 
advanced technology.  In areas such as Boston that use what is 
referred to as "small cell" technology, CSLI can identify an 
 
 
4 Global positioning system. 
7 
 
individual's location precisely, down to the specific floor of a 
particular building.  See State v. Earls, 214 N.J. 564, 578 
(2013), quoting Blaze Testimony I, supra at 25.  See also 
National League of Cities, Small Cell Wireless Technology in 
Cities, at 8-9 (2018) (discussing Boston's use of small cell 
technology).5  This technology is becoming increasingly 
ubiquitous; "[b]y some estimates, the number of these small-
scale cellular base stations equaled or outstripped the number 
of conventional cells in the [United States] in 2010, and their 
deployment continues to grow at a very fast rate."  ECPA, Part 
2:  Geolocation Privacy and Surveillance:  Hearing Before the 
Subcomm. on Crime, Terrorism, and Homeland Security of the H. 
Comm. on the Judiciary, 113th Cong., at 55 (2013) (testimony of 
Professor Matt Blaze). 
 
In conducting a criminal investigation, law enforcement 
officers may obtain targeted CSLI, which provides a log of every 
cell site to which an individual cellular telephone has 
connected within a given time frame, thus enabling investigators 
retroactively to reconstruct an individual's movements over 
time.  See Augustine I, 467 Mass. at 239.  A tower dump, by 
contrast, provides officers with CSLI from every device that 
connected to a particular cell site within a specified period; 
 
5 Available at https://www.nlc.org/wp-content/uploads/2018 
/08/CS_SmallCell_MAG_FINAL.pdf [https://perma.cc/8CKW-KJZ8]. 
8 
 
allowing law enforcement to infer that the owners of those 
devices most likely were present in that site's coverage area 
during that time.  See Carpenter, 138 S. Ct. at 2220 (tower dump 
is "a download of information on all the devices that connected 
to a particular cell site during a particular interval").  Tower 
dumps have proved particularly useful in investigating serial 
crimes, because they enable investigators to isolate individual 
devices that were near the scene of multiple offenses.  See 
Owsley, The Fourth Amendment Implications of the Government's 
Use of Cell Tower Dumps in Its Electronic Surveillance, 16 U. 
Pa. J. Const. L. 1, 6 (2013). 
 
b.  Factual background.  On September 22, September 27, 
September 28, October 4, October 25, and October 31, 2018, 
clerks at six stores in Boston, Canton, and Cambridge were 
robbed at gunpoint by an unidentified perpetrator.  On 
October 6, 2018, an unidentified individual shot and killed a 
store clerk in Boston during an attempted robbery.  Almost all 
of the stores were convenience stores or gasoline stations, and 
one sold cellular telephones.  Because each of the robberies was 
perpetrated in a comparable manner by a man fitting a similar 
description, police suspected that the same person had been 
responsible for all seven incidents.  Based on surveillance 
footage and witness statements, investigators also believed that 
9 
 
the perpetrator was at least occasionally assisted by a 
coventurer who acted as a getaway driver. 
Boston police detectives worked together with agents from 
the Federal Bureau of Investigation (FBI) to identify a suspect.  
They sought to do so by cross-referencing a series of tower 
dumps in order to determine if any device had been near the 
scenes of two or more of the incidents.  To this end, on 
October 26, 2018, an agent with the FBI obtained a search 
warrant from a Federal magistrate judge, see 18 U.S.C. § 2703, 
for tower dumps corresponding to the robberies in Boston, 
Canton, and Cambridge on September 22, September 27, 
September 28, and October 4, 2018 (first warrant).  The first 
warrant required four service providers with one or more cell 
sites near the scenes of the robberies to produce the tower 
dumps.  For each date, the tower dump was to include the CSLI 
for all cellular telephones that had connected to any cell site 
providing cellular service to the address where the robbery 
occurred, within a fifteen-minute period surrounding the time of 
the incident. 
 
On January 30, 2019, a Boston police detective sought and 
obtained a search warrant from a judge in the Boston Municipal 
Court, see G. L. c. 276, §§ 1-7, for tower dumps corresponding 
to the robberies in Boston and Canton on October 25 and 
October 31, 2018, as well as the attempted robbery and homicide 
10 
 
in Boston on October 6, 2018 (second warrant).  The application 
for this second warrant did not reference or otherwise rely upon 
any evidence obtained from execution of the first warrant.  The 
second warrant required the same four service providers to 
produce the tower dumps.  For each date, the tower dump was to 
include CSLI for all cellular telephones that had connected to 
any cell site serving the address where the crime occurred, 
within a forty-minute period around the time of each incident. 
 
Both warrants sought the same categories of information.  
For each cellular telephone that connected to the relevant cell 
site, the providers were required to furnish (1) the location 
and sector of the cell site providing service; (2) the telephone 
number and unique identifier,6 either of which could be used to 
identify the owner of the telephone; (3) the type of 
communication initiated or received when the connection 
occurred; (4) the telephone number of the device initiating the 
communication (known as the "source number"); (5) the telephone 
number of the device receiving the communication (the 
 
6 A "unique identifier" is a distinctive series of numbers 
that cellular service providers use to identify a device or its 
user.  See Citizen Lab of the Munk School of Global Affairs at 
the University of Toronto, The Many Identifiers in Our Pockets:  
A Primer on Mobile Privacy and Security (May 13, 2015), 
https://citizenlab.ca/wp-content/uploads/2015/05/The-Many-
Identifiers-in-Our-Pockets-A-primer-on-mobile-privacy-and-
security-_reportPDF.pdf [https://perma.cc/55P6-G43X]. 
11 
 
"destination number"); and (6) the date, time, and duration of 
each communication. 
 
Collectively, execution of the search warrants produced 
information on over 50,000 unique telephone numbers.  
Investigators then cross-referenced the data from each tower 
dump in an effort to identify any telephone numbers that 
appeared in two or more of the tower dumps, and discovered that 
a particular telephone number appeared in the tower dump 
corresponding to the homicide on October 6, 2018, as well as the 
tower dump corresponding to the robbery on October 31, 2018.  
Investigators determined, by searching a police database, that 
this number belonged to the defendant.7  They also learned that, 
at around the time of the shooting on October 6, 2018, the 
defendant's telephone had been in communication with another 
device, which they suspected to have belonged to the getaway 
driver.  Investigators were able to determine the identity of 
the suspected coventurer, as well as the fact that his cellular 
telephone number appeared in the tower dumps corresponding to 
the robberies on September 22, October 6, and October 31, 2018. 
 
7 Following an unrelated traffic accident, the defendant 
previously had provided his telephone number to police. 
 
12 
 
 
Based on this, investigators identified the defendant as a 
suspect in six of the incidents, including the homicide.8  The 
defendant was indicted on a charge of murder in the first 
degree, G. L. c. 265, § 1; attempted masked armed robbery, G. L. 
c. 274, § 6; five counts of masked armed robbery, G. L. c. 265, 
§ 17; and six counts of unlawful possession of a firearm, G. L. 
c. 269, § 10 (a).  He moved to suppress all of the evidence 
obtained as a result of the tower dumps, on the ground that it 
was the fruit of an unconstitutional search. 
 
Following a nonevidentiary hearing, a Superior Court judge 
denied the motion.  The judge concluded that the defendant had a 
reasonable expectation of privacy in his CSLI, and therefore had 
standing to challenge the purported search.  Nonetheless, 
because the search warrants had been supported by probable 
cause, the judge decided that the CSLI, and the evidence 
subsequently derived from it, had been obtained lawfully.  The 
judge found that both search warrants were sufficiently 
particular and limited in scope, and rejected the defendant's 
argument that they amounted to "overbroad, unparticularized 
general warrants."  The defendant then sought leave to pursue an 
 
8 After having obtained the first warrant, but before 
applying for the second warrant, the Commonwealth decided that 
it could not "definitively" determine that the perpetrator who 
carried out the other offenses was responsible for the robbery 
on September 28, 2018. 
13 
 
interlocutory appeal in the county court.  A single justice of 
this court allowed the application and reserved and reported the 
matter to the full court. 
 
2.  Discussion.  a.  Standard of review.  Ordinarily, "[i]n 
reviewing a decision on a motion to suppress, 'we accept the 
judge's subsidiary findings of fact absent clear error but 
conduct an independent review of [the] ultimate findings and 
conclusions of law" (quotation omitted).  Commonwealth v. Ramos, 
470 Mass. 740, 742 (2015), quoting Commonwealth v. Colon, 449 
Mass. 207, 214, cert. denied, 552 U.S. 1079 (2007).  Where, as 
here, the judge's findings are based exclusively on documentary 
evidence, we review the judge's findings of fact, as well as his 
or her conclusions of law, de novo.  See Commonwealth v. 
Johnson, 481 Mass. 710, 714, cert. denied, 140 S. Ct. 247 
(2019). 
 
b.  Whether a search occurred.  i.  Legal standards.  The 
Fourth Amendment to the United States Constitution and art. 14 
protect the right to be free from unreasonable searches.9  See 
 
9 State constitutional rules "do[] not constrain Federal 
authorities unless they operate as part of an 'essentially' 
State investigation."  Commonwealth v. Brown, 456 Mass. 708, 713 
(2010), S.C., 466 Mass. 1007 (2013).  An investigation is 
essentially a State investigation where, for example, the 
purpose of the investigation was to bring State charges, State 
officials retained significant authority over the investigation, 
or the State's involvement was otherwise so substantial that it 
"negate[d] the essentially Federal nature of the investigation."  
Commonwealth v. Gonzalez, 426 Mass. 313, 317-318 (1997).  The 
14 
 
Commonwealth v. Feliz, 486 Mass. 510, 514 (2020).  Of course, 
for those protections to be applicable, "the Commonwealth's 
conduct must constitute a search in the constitutional sense."  
See Johnson, 481 Mass. at 715.  Such a search occurs "when the 
government's conduct intrudes on a person's reasonable 
expectation of privacy."10  Augustine I, 467 Mass. at 241.  "An 
individual has a reasonable expectation of privacy where (i) the 
individual has 'manifested a subjective expectation of privacy 
in the object of the search,' and (ii) 'society is willing to 
recognize that expectation as reasonable.'"  Johnson, supra, 
quoting Augustine I, supra at 242. 
 
In applying this test to technological surveillance, we 
must be careful to "assure[] preservation of that degree of 
privacy against government that existed when the Fourth 
Amendment was adopted."  Carpenter, 138 S. Ct. at 2214, quoting 
Kyllo v. United States, 533 U.S. 27, 34 (2001).  In practice, 
doing so is anything but a simple exercise; advancements in 
 
Commonwealth does not dispute that the investigation in this 
case was essentially a State investigation.  Accordingly, the 
Federal agents involved in the investigation were constrained by 
the State Constitution.  See Commonwealth v. Jarabek, 384 Mass. 
293, 297 (1981). 
 
10 Because the defendant does not contend that the 
government "physically intrud[ed] on a constitutionally 
protected area," we do not consider whether a physical search 
occurred.  See Commonwealth v. Johnson, 481 Mass. 710, 715, 
cert. denied, 140 S. Ct. 247 (2019), quoting Grady v. North 
Carolina, 575 U.S. 306, 309 (2015). 
15 
 
technology have resulted in a quantity and quality of 
surveillance that never could have been imagined, let alone 
realized, at the time of the founding.  See United States v. 
Jones, 565 U.S. 400, 420 (2012) (Alito, J., concurring in the 
judgment).  Thus, while we have "acknowledged the usefulness of 
these tools in crime detection," we also have "caution[ed] 
against allowing the 'power of technology to shrink the realm of 
guaranteed privacy.'"  Commonwealth v. Henley, 488 Mass. 95, 109 
(2021).  See Commonwealth v. Blood, 400 Mass. 61, 69 (1987), 
quoting Lopez v. United States, 373 U.S. 427, 469 (1963) 
(Brennan, J., dissenting) ("[i]t must be plain that electronic 
surveillance imports a peculiarly severe danger to the liberties 
of the person"). 
 
To this end, where police use technology to engage in long-
term surveillance, we have analyzed their actions in the 
aggregate.  We first did so with respect to CSLI in Augustine I, 
467 Mass. at 253.  There, we held that the government 
effectuated a search when it used targeted CSLI to obtain a list 
of every cell site to which the defendant's cellular telephone 
had connected over a two-week period.  Id. at 254-255.  In so 
holding, we considered the "cumulative nature of the information 
collected"; that is, rather than evaluating whether the 
defendant had a reasonable expectation of privacy in each 
isolated cell site connection, we evaluated whether the 
16 
 
defendant had such a reasonable expectation in the two weeks of 
CSLI as a whole.  Id. at 253-255. 
 
The aggregation principle we used in Augustine I developed 
into what is now known as the mosaic theory.  See Commonwealth 
v. McCarthy, 484 Mass. 493, 503 (2020).  "The mosaic theory 
requires that we consider the governmental action as a whole and 
evaluate the collected data when aggregated."  Henley, 488 Mass. 
at 109.  Thus, rather than "asking if a particular act is a 
search, the mosaic theory asks whether a series of acts that 
[may not be] searches in isolation amount to a search when 
considered as a group."  Kerr, The Mosaic Theory of the Fourth 
Amendment, 111 Mich. L. Rev. 311, 320 (2012).  Because "the 
whole reveals far more than the sum of the parts," a series of 
acts may be a search even where each step in isolation is not.  
McCarthy, supra at 504.  See District of Columbia v. Wesby, 138 
S. Ct. 577, 588 (2018).  "As the analogy goes, the color of a 
single stone depicts little, but by stepping back one can see a 
complete mosaic."  McCarthy, supra.  See United States v. 
Tuggle, 4 F.4th 505, 517 (7th Cir. 2021), cert. denied, 142 S. 
Ct. 1107 (2022), quoting Kugler & Strahilevitz, Actual 
Expectations of Privacy, Fourth Amendment Doctrine, and the 
Mosaic Theory, 2015 Sup. Ct. Rev. 205, 205 (2015) ("the mosaic 
theory attempts to capture the idea that the 'government can 
17 
 
learn more from a given slice of information if it can put that 
information in the context of a broader pattern, a mosaic'"). 
 
In determining whether a series of acts constitutes a 
search under the mosaic theory, courts have considered "whether 
the surveillance was so targeted and extensive that the data it 
generated, in the aggregate, exposed otherwise unknowable 
details of a person's life."  Commonwealth v. Mora, 485 Mass. 
360, 373 (2020).  See Carpenter, 138 S. Ct. at 2217-2218 
("Mapping a cell phone's location [using targeted CSLI] over the 
course of 127 days" constituted search because it revealed "an 
intimate window into a person's life" that could not be obtained 
using traditional surveillance); United States v. Wilford, 961 
F. Supp. 2d 740, 771 (D. Md. 2013), aff'd, 689 Fed. Appx. 727 
(4th Cir. 2017), cert. denied, 138 S. Ct. 2707 (2018), quoting 
United States v. Graham, 846 F. Supp. 2d 384, 401-403 (D. Md. 
2012), aff'd, 824 F.3d 421 (4th Cir. 2016), cert. denied, 138 S. 
Ct. 2700 (2018) (mosaic theory turns on whether "discrete acts 
of surveillance . . . in the aggregate . . . 'paint an "intimate 
picture"' of a defendant's life"). 
 
To answer this question, our limited precedent to date 
primarily has focused on three general concerns:  the extent to 
which the surveillance reveals the whole of an individual's 
public movements; the character of the information obtained; and 
whether the surveillance could have been achieved using 
18 
 
traditional law enforcement techniques.  See Henley, 488 Mass. 
at 113; Mora, 485 Mass. at 373-374; McCarthy, 484 Mass. at 506, 
508-509; Augustine I, 467 Mass. at 248, 253.  The same concerns 
have animated the Federal cases that have addressed the issue.  
See Carpenter, 138 S. Ct. at 2217-2218 (targeted CSLI provides 
"an all-encompassing record of the holder's whereabouts" and 
therefore reveals "an intimate window into a person's life" that 
could not have been obtained under traditional surveillance).  
See, e.g., United States v. Trice, 966 F.3d 506, 518 (6th Cir. 
2020), cert. denied, 141 S. Ct. 1395 (2021), quoting Carpenter, 
supra (in evaluating duration of surveillance, considering 
whether it "provided law enforcement with information that was 
'otherwise unknowable,'" and "provided an 'intimate window into 
a person's life'").  See also Leaders of a Beautiful Struggle v. 
Baltimore Police Dep't, 2 F.4th 330, 342-343 (4th Cir. 2021) 
(electronic aerial surveillance violates reasonable expectation 
of privacy because it "yield[s] 'a wealth of detail'" that 
"surpassed ordinary expectations of law enforcement's capacity 
and provided enough information to deduce details from the whole 
of individuals' movements" [citation omitted]); State v. Jones, 
2017 S.D. 59, ¶¶ 29, 31, 36, cert. denied, 138 S. Ct. 1011 
(2018) (search occurred where surveillance that "allowed law 
enforcement to enhance their senses" revealed "the aggregate of 
all of [the defendant's] coming and going from the home," thus 
19 
 
providing investigators with "a mosaic of intimate details of 
[the defendant's] private life and associations"). 
 
Whether surveillance reveals the whole of a defendant's 
movements turns on the duration of the surveillance, as well as 
its degree of comprehensiveness.  See, e.g., Augustine I, 467 
Mass. at 254.  Long-term surveillance raises particular concerns 
because it uncovers "types of information not revealed by short-
term surveillance, such as what a person does repeatedly, what 
he does not do, and what he does ensemble," United States v. 
Maynard, 615 F.3d 544, 562 (D.C. Cir. 2010), aff'd, 564 U.S. 
1036 (2011), thus providing "an intimate window into a person's 
life" as it existed throughout the duration of the surveillance, 
Carpenter, 138 S. Ct. at 2217.  Such a pattern of activity is 
far more revealing than details from isolated incidents.  See 
Mora, 485 Mass. at 375-376.  "The difference is not one of 
degree but of kind, for no single journey reveals the habits and 
patterns that mark the distinction between a day in the life and 
a way of life . . . ."  Maynard, supra.  By way of illustration, 
a single trip to the liquor store reveals little about an 
individual, but daily trips over the course of a month reveal 
much more. 
 
A record is considered to be comprehensive if it has 
sufficiently voluminous and detailed information from which 
investigators can derive a relatively complete picture of an 
20 
 
individual's "comings and goings" over time, even if there are 
gaps in the record.  See Carpenter, 138 S. Ct. at 2219.  For 
example, in Augustine I, 467 Mass. at 254-255, we determined 
that the defendant had a reasonable expectation of privacy in 
the whole of his public movements, as revealed by targeted CSLI 
from a single cellular telephone that had accompanied him during 
a two-week trip, despite the fact that his location was only 
revealed when he made or received a telephone call.  See Jones, 
565 U.S. at 404 (electronic tracking of particular vehicle's 
location provided investigators with whole of defendant's 
movements, even though tracking only revealed defendant's 
location while in vehicle); Leaders of a Beautiful Struggle, 2 
F.4th at 342-343 (rejecting argument that "gaps in the data" 
nullified reasonable expectation of privacy in public 
movements).  Even where a record does not include each and every 
one of a defendant's movements, "the likelihood a stranger would 
observe all those movements is not just remote, it is 
essentially nil.  It is one thing for a passerby to observe or 
even to follow someone during a single journey as he goes to the 
market or returns home from work.  It is another thing entirely 
for that stranger to pick up the scent again the next day and 
the day after that, week in and week out, dogging his prey until 
he has identified all the places, people, amusements, and chores 
21 
 
that make up that person's hitherto private routine."  McCarthy, 
484 Mass. at 504, quoting Maynard, 615 F.3d at 560. 
 
We also have considered the extent to which the 
surveillance, even if less comprehensive, tended to reveal 
highly intimate or personal details.  See, e.g., Mora, 485 Mass. 
at 370-372.  Because "art. 14 protects against warrantless 
intrusion into private places," we have expressed particular 
concern over surveillance that reveals individuals in private 
settings.  See, e.g., Augustine I, 467 Mass. at 253 ("we cannot 
ignore the probability that, as CSLI becomes more precise, 
cellular telephone users will be tracked in constitutionally 
protected areas").  Such surveillance permits investigators to 
infer whether and when an individual is in constitutionally 
sensitive areas, such as the home or a place of worship.  See 
Commonwealth v. Yusuf, 488 Mass. 379, 386 (2021), quoting 
Caniglia v. Strom, 141 S. Ct. 1596, 1599 (2021) ("The very core 
of [the constitutional] guarantee is the right of a man to 
retreat into his own home and there be free from unreasonable 
governmental intrusion" [alterations in original]).  Once 
investigators obtain such information, they are able to piece 
together "a highly detailed profile, not simply of where we go, 
but by easy inference, of our associations -- political, 
religious, amicable and amorous, to name only a few -- and the 
pattern of our professional and avocational pursuits.'"  
22 
 
McCarthy, 484 Mass. at 504-505, quoting Commonwealth v. 
Connolly, 454 Mass. 808, 834 (2009) (Gants, J., concurring), 
cert. denied, 574 U.S. 1085 (2015). 
 
This information is private and personal even when 
anonymized, but it provides a much richer profile of an 
individual if it is linked to his or her identity.  See United 
States Dep't of State v. Ray, 502 U.S. 164, 176 (1991) 
("Although disclosure of [certain] personal information 
constitutes only a de minimis invasion of privacy when the 
identities of the [individuals] are unknown, the invasion of 
privacy becomes significant when the personal information is 
linked to particular [individuals]").  There is, after all, a 
significant difference between knowing that an anonymized 
somebody was at a specific political rally and knowing that 
"John Smith" was at that rally.  See Globe Newspaper Co. v. 
Boston Retirement Bd., 388 Mass. 427, 435 n.14 (1983) 
(anonymized information "which did not allow the identification 
of any individual" was not "of a personal nature"). 
 
Providing law enforcement with such personal information is 
of particular concern because it risks chilling the 
associational and expressive freedoms that our State and Federal 
Constitutions strive to protect.  See Jones, 565 U.S. at 416 
(Sotomayor, J., concurring) ("Awareness that the government may 
be watching chills associational and expressive freedoms"); 
23 
 
United States v. Moore-Bush, 381 F. Supp. 3d 139, 148 (D. Mass. 
2019) (long-term surveillance "risks chilling core First 
Amendment activities").  Privacy in one's associations, whether 
political, religious, or simply amicable, plays a crucial role 
in maintaining our democracy, and therefore is protected under 
art. 14.  See, e.g., National Ass'n for the Advancement of 
Colored People v. Alabama, 357 U.S. 449, 462 (1958) (recognizing 
"the vital relationship between freedom to associate and privacy 
in one's associations"); Blood, 400 Mass. at 69 (art. 14 
protects "the right to be known to others and to know them, and 
thus to be whole as a free member of a free society"). 
 
We also have considered whether the electronic surveillance 
generated a category or quantity of information that could not 
have been obtained using traditional law enforcement tools.  
See, e.g., McCarthy, 484 Mass. at 500.  To this end, we have 
examined whether the surveillance allowed the government to 
"track and reconstruct a person's past movements, a category of 
information that never would be available through the use of 
traditional law enforcement tools of investigation" (emphasis in 
original).  See Augustine I, 467 Mass. at 254.  Even where the 
surveillance at issue theoretically could have been accomplished 
using traditional surveillance methods, we have taken into 
account whether those methods would have been prohibitively 
expensive or otherwise impracticable.  See, e.g., McCarthy, 
24 
 
supra at 499-500, quoting Jones, 565 U.S. at 429 (Alito, J., 
concurring) ("[I]n the pre-computer age, the greatest 
protections of privacy were neither constitutional nor 
statutory, but practical.  Traditional surveillance for any 
extended period of time was difficult and costly and therefore 
rarely undertaken").  Because "[h]umans are imperfect note-
takers and not all blessed with photographic memory," 
traditional surveillance often cannot achieve the same level of 
volume, detail, and precision as electronic surveillance.  
Moore-Bush, 381 F. Supp. 3d at 149.  Moreover, as it is 
"unlikely that investigators could . . . maintain[] in-person 
observation over the course of multiple months without [their 
targets] becoming aware of their presence," technological 
surveillance that proceeds surreptitiously empowers 
investigators to engage in long-term, secret surveillance that 
would not otherwise be possible.  See Mora, 485 Mass. at 374. 
 
While these factors have emerged as preeminent in the few 
cases in which we have applied the mosaic theory to date, we 
emphasize that the question whether electronic surveillance 
exposes otherwise unknowable details of a person's life must be 
answered in light of the totality of the circumstances in each 
case.  Accordingly, these factors are not exhaustive, and no one 
factor is determinative.  A few examples are illustrative. 
25 
 
 
In McCarthy, 484 Mass. at 508-509, for instance, we decided 
that police did not intrude on a defendant's reasonable 
expectation of privacy where they used information obtained from 
four automatic license plate readers (ALPRs),11 in fixed 
positions on either side of two bridges, to determine when, over 
a period of months, a defendant crossed the bridges.  We 
recognized that the ALPRs provided police with surveillance 
capabilities that exceeded what would have been possible using 
traditional law enforcement techniques, but nonetheless reasoned 
that the limited number of ALPRs, positioned on public highways 
leading to and from the Cape Cod peninsula, did not "allow the 
Commonwealth to monitor the whole of the defendant's public 
movements" or otherwise "reveal 'the privacies of life.'"  Id. 
at 509, quoting Carpenter, 138 S. Ct. at 2217.  We noted, 
however, that even a limited number of ALPRs located near 
"constitutionally sensitive locations," such as the home or a 
place of worship, could intrude upon a reasonable expectation of 
privacy because they "reveal more of an individual's life and 
associations."  McCarthy, supra at 506. 
 
11 "Automatic license plate readers are cameras combined 
with software that allows them to identify and 'read' license 
plates on passing vehicles.  When an ALPR identifies a license 
plate, it records a photograph of the plate, the system's 
interpretation of the license plate number, and other data, such 
as the date, time, location, direction of travel, and travel 
lane."  Commonwealth v. McCarthy, 484 Mass. 493, 494 (2020). 
26 
 
 
Thus, where surveillance falls short of revealing the whole 
of an individual's movements, it nonetheless may constitute a 
search when it reveals highly intimate details that practically 
would not have been obtainable using traditional surveillance.  
See Mora, 485 Mass. at 369.  In Mora, supra at 375-376, we 
decided that police had effectuated a search by installing and 
monitoring two pole cameras pointed at the defendants' 
residences.  The cameras revealed when the defendants were at 
home, when they received visitors, and who those visitors were, 
and therefore did not reveal the whole of the defendants' 
movements.  See id. at 371-372.  Nonetheless, we concluded that 
the cameras intruded upon the defendants' reasonable 
expectations of privacy because the information revealed by the 
surveillance provided investigators with highly intimate details 
of the defendants' lives that could not have been obtained using 
traditional surveillance methods.  See id. at 374, quoting 
Jones, 565 U.S. at 420 n.3 (Alito, J., concurring) ("replicating 
pole camera surveillance 'would have required either a very 
large [pole], a very tiny constable, or both'"). 
 
ii.  Application.  Here, we must determine whether the 
government's actions with respect to the seven tower dumps, in 
the aggregate, intruded upon the defendant's reasonable 
expectation of privacy by providing investigators with otherwise 
27 
 
unknowable details of life.12  We begin by aggregating the 
several actions investigators took in acquiring and analyzing 
the defendant's CSLI.  See Henley, 488 Mass. at 113.  
Investigators first obtained seven tower dumps, spanning seven 
different days over the course of slightly more than one month; 
each tower dump was limited in time to the period immediately 
before and after the specific robbery for which the CSLI was 
sought.  Investigators then cross-referenced the information 
obtained from the tower dumps to isolate particular telephone 
numbers that appeared at more than one location.  Thereafter, 
investigators analyzed the CSLI associated with those telephone 
numbers, among them the defendant's telephone number, to 
determine (1) the approximate location of the connecting 
cellular telephone, (2) the identity of the telephone's user, 
and (3) the identity of the person with whom the user was 
communicating. 
 
These actions, viewed in their entirety, provided 
investigators with information of a highly personal and private 
 
12 The Commonwealth does not dispute that the defendant 
manifested a subjective expectation of privacy in his CSLI 
records.  The defendant submitted an affidavit averring that he 
never affirmatively permitted law enforcement officers to access 
his CSLI.  See Augustine I, 467 Mass. at 255 & n.38 (subjective 
expectation of privacy was satisfied where defendant averred 
that he "never permit[ed] the police or other law enforcement 
officials access to his telephone records").  Accordingly, we 
focus on the reasonableness of the defendant's subjective 
expectation. 
28 
 
nature.  Because tower dumps locate individuals when they are in 
private settings just as easily as when they are in public 
settings, they have "the potential to track a cellular telephone 
user's location in constitutionally protected areas."  
Augustine I, 467 Mass. at 249.  Moreover, tower dumps enable 
investigators to infer the identity of the individual with whom 
the user of a particular device was communicating at the moment 
the device connected to the cell site, and therefore provide 
investigators with significant insight into the individual's 
associations. 
 
An owner's location and associations are tied to his or her 
telephone number and unique identifier, which, here, were used 
to discern the defendant's identity and that of his suspected 
accomplice.  Moreover, because investigators obtained seven 
tower dumps spanning seven distinct dates over the course of 
more than one month, they also were able to piece together a 
pattern of behavior, that is, not only where an individual was 
and with whom he or she associated on one occasion, but also 
where the individual had been and with whom the individual had 
associated on multiple different occasions. 
 
The collective whole of this personal and private 
information would have been impossible to obtain through the use 
of traditional surveillance techniques.  The government learned 
the defendant's comings and goings during a period of time 
29 
 
before he was a suspect, something that could not have been 
achieved through visual surveillance.  See Augustine I, 467 
Mass. at 254.  Indeed, the sheer volume of information 
investigators obtained from the tower dumps would have been 
impossible to gather using traditional surveillance.  See id.  
There is no historic analogue for the ability effortlessly to 
compile and document the locations, identities, and associations 
of tens of thousands of individuals, just in case one might be 
implicated in a criminal act.13  Even if such a feat were 
possible, it certainly would be impossible to execute 
surreptitiously; yet, here, investigators were able to compile 
and catalogue the locations of more than 50,000 individuals at 
varying points over more than one month, without any one of them 
ever knowing that he or she was the target of police 
surveillance. 
 
In light of these factors, and in the totality of the 
circumstances, the collection and subsequent analysis of the 
seven tower dumps at issue here provided investigators with 
 
13 Traffic cameras might provide the closest analogue, 
insofar as they can reveal the retrospective location of 
potentially a substantial number of people.  Traffic cameras, 
however, only locate a person in public areas, whereas tower 
dumps provide information about public and private locations.  
Moreover, while traffic cameras may reveal an individual's 
physical features, tower dumps enable investigators to determine 
a person's precise identity using his or her telephone number or 
unique identifier. 
30 
 
highly personal and previously unknowable details of the 
defendant's life.  Accordingly, the Commonwealth's use of the 
seven tower dumps intruded upon the defendant's reasonable 
expectation of privacy. 
 
The Commonwealth contends that the government's actions 
here should not be considered a search because the seven tower 
dumps only produced, in total, three hours of CSLI.  In support 
of its position, the Commonwealth points to Commonwealth v. 
Estabrook, 472 Mass. 852, 858 (2015), where the court held that 
no search takes place when police obtain six or fewer hours of 
targeted CSLI, giving them a list of each cell site with which 
an identified cellular telephone has connected during that 
period.  We reasoned that, although government collection and 
use of targeted CSLI over a longer period of time intrudes upon 
an individual's reasonable expectation of privacy, location 
information covering six hours or less is too brief in duration 
to do so.  Id. 
 
While Estabrook, 472 Mass. at 855, involved targeted CSLI, 
its reasoning also is applicable to tower dumps.  Given that 
tower dumps reveal an individual's locations at discrete moments 
in time, the individual privacy interests implicated by tower 
dumps are akin to those implicated by targeted CSLI.14  Compare 
 
14 The defendant argues that there is a heightened privacy 
interest in the context of tower dumps because they provide CSLI 
31 
 
McCarthy, 484 Mass. at 509 (no reasonable expectation of privacy 
in location of individual's vehicle, as revealed by limited 
number of cameras in particular public location, at specific 
point in time), with Commonwealth v. Rousseau, 465 Mass. 372, 
382 (2013) (reasonable expectation of privacy in entirety of 
vehicle's movements over thirty-one days).  The court's holding 
in Estabrook, supra at 858, is inapplicable here; the holding 
permits a warrantless search of up to six continuous hours of 
CSLI, where, here, the government obtained small increments of 
CSLI, each falling on a separate day.  The rationale in 
Estabrook was that analyzing six hours or less of telephone call 
CSLI could not be a search "because the duration is too brief to 
implicate the person's reasonable privacy interest."  See id., 
quoting Augustine I, 467 Mass. at 254.  While the court has 
determined that analyzing six continuous hours of CSLI does not 
intrude upon a reasonable expectation of privacy, analyzing 
small increments of CSLI over the course of several days does.  
Whereas the former reveals at most one-quarter of one day's 
 
on "potentially thousands of innocent persons."  The rights 
secured by art. 14, however, "are specific to the individual."  
Commonwealth v. Delgado-Rivera, 487 Mass. 551, 554 (2021), cert. 
denied, 142 S. Ct. 908 (2022).  Thus, in determining whether a 
search occurred, we focus exclusively on the defendant's privacy 
interests, and cannot consider the privacy interests of others.  
See id. at 556, 564 (defendant could not rely on codefendant's 
reasonable expectation of privacy in cellular telephone in 
establishing that search occurred). 
32 
 
activities, the latter reveals a pattern of activity, which 
implicates comparatively greater privacy interests.  See Mora, 
485 Mass. at 375-376.  Accordingly, although Estabrook, supra, 
enables the Commonwealth to obtain one or more tower dumps 
spanning six hours or less without a warrant, it provides no 
refuge where, as here, the tower dumps span multiple days. 
 
c.  Whether the Commonwealth's acquisition of the tower 
dumps was constitutionally infirm.  Because the Commonwealth's 
actions constituted a search, we must determine whether its 
conduct in effectuating that search was reasonable. 
 
Article 14 "require[s] that all searches and seizures be 
reasonable."  Commonwealth v. Alexis, 481 Mass. 91, 97 (2018).  
"Searches and seizures conducted outside the scope of a valid 
warrant are presumed to be unreasonable," and therefore 
unconstitutional.  Commonwealth v. Balicki, 436 Mass. 1, 8 
(2002).  "To be reasonable in the constitutional sense," a 
search conducted pursuant to a warrant must be supported by 
probable cause.  Commonwealth v. Neilson, 423 Mass. 75, 77 
(1996).  To comport with constitutional protections, an 
affidavit in support of a search warrant for CSLI must 
demonstrate "probable cause to believe [1] 'that a particularly 
described offense has been, is being, or is about to be 
committed, and [2] that [the CSLI being sought] will produce 
evidence of such offense or will aid in the apprehension of a 
33 
 
person who the applicant has probable cause to believe has 
committed, is committing, or is about to commit such offense'" 
(alterations in original).  Estabrook, 472 Mass. at 870, quoting 
Augustine I, 467 Mass. at 256.  Accordingly, the warrant 
affidavit must show "a sufficient nexus between the criminal 
activity for which probable cause has been established and the 
physical location of the cell phone recorded by the CSLI."  
Commonwealth v. Hobbs, 482 Mass. 538, 547 (2019).  A nexus is 
sufficient where "the information available to police 
'provide[s] a substantial basis for concluding that evidence 
connected to the crime will be found [in] the [location to be 
searched]."  See Commonwealth v. Ortiz, 487 Mass. 602, 606 
(2021), quoting Commonwealth v. Escalera, 462 Mass. 636, 642 
(2012). 
 
i.  Probable cause.  The defendant argues that the search 
of the CSLI here was unlawful because neither supporting 
affidavit established probable cause.  Specifically, he 
maintains that the search warrant affidavits did not demonstrate 
a nexus between the commission of the offenses and the CSLI to 
be searched, as the affidavits did not set forth particularized 
evidence that the perpetrator had used a cellular telephone 
during the commission of the offenses, or in the periods 
immediately before or thereafter.  Relying on Commonwealth v. 
Morin, 478 Mass. 415, 426 (2017), the defendant contends that 
34 
 
the only statements in the affidavits demonstrating that the 
perpetrator "possessed a phone during the robberies" were 
general conclusions about the ubiquity of cellular telephones, 
which cannot be used to establish probable cause.15  See id. (in 
demonstrating existence of probable cause to search contents of 
cellular telephone, "police may not rely on the general 
ubiquitous presence of cellular telephones in daily life, or an 
inference that friends or associates most often communicate by 
cellular telephone, as a substitute for particularized 
information that a specific device contains evidence of a 
crime"). 
 
As the defendant contends, to establish probable cause to 
search the contents of a cellular telephone, "it is not enough 
that the object of the search may be found in the place subject 
to search. . . .  Rather, the affidavit must demonstrate 
that . . . the items sought will be located in the particular 
data file . . . to be searched" (emphasis in original).  
Commonwealth v. Broom, 474 Mass. 486, 496 (2016).  General 
statements concerning the ubiquity of cellular telephones are 
 
15 The affidavit in support of the second warrant stated 
that "[s]mart phone/electronic device utilization is one of the 
most common activities today and the vast majority of American 
society bring their device [wherever] they go, almost by habit."  
Similarly, the affidavit in support of the first warrant stated 
that "it is very common for a person to have a cellular 
telephone with them at all times, even during and after the 
commission of a crime." 
35 
 
insufficient to establish the required nexus.  See Morin, 478 
Mass. at 426.  This "more narrow and demanding standard," 
however, is applicable to searches of cellular telephones and 
computer-like devices, see Hobbs, 482 Mass. at 547 n.11, quoting 
Commonwealth v. Holley, 478 Mass. 508, 524 (2017), and not to 
searches of CSLI.  While a search of the contents of a cellular 
telephone permits police to view "vast amounts of sensitive and 
private data," the "same concerns are not present in the context 
of CSLI, where the cell phone's location, and not its contents, 
is sought."  Hobbs, supra.  Thus, when seeking a warrant to 
search CSLI, investigators need not establish "that the 
defendant actually used or possessed his [or her] cell phone 
during the commission of the crimes" (emphasis added), which 
they would be required to do in order to search its contents.  
See id. at 546.  Rather, the nexus requirement is satisfied as 
long as there is a substantial basis to conclude that the 
defendant used his or her cellular telephone during the relevant 
time frame, such that there is probable cause to believe the 
sought after CSLI will produce evidence of the crime.  See id. 
 
Here, it is undisputed that the Commonwealth established 
probable cause to believe that the offenses described in the 
warrant had been committed.  Accordingly, we consider whether 
each warrant affidavit established a substantial basis to 
believe that a search of the requested tower dumps would produce 
36 
 
evidence of the crimes under investigation, or would aid in the 
apprehension of the perpetrator.  See Estabrook, 472 Mass. 
at 870.  Because the probable cause analysis is "fact-intensive 
and [must] be resolved on a case-by-case basis," we review each 
warrant application separately.  See Commonwealth v. Vasquez, 
482 Mass. 850, 867 (2019), S.C., 485 Mass. 405 (2020), cert. 
denied, 141 S. Ct. 2601 (2021).  We begin with the second 
warrant, in which the warrant affidavit discussed all of the 
offenses under investigation in depth, before considering the 
less-detailed first warrant.16 
 
A.  Second warrant.  The second search warrant affidavit 
described several notable similarities between the offenses.  
Each robbery, as well as the attempted robbery, was committed 
against a clerk at a store, almost always a convenience store, 
in or around Boston, sometime during the period between dusk and 
dark.  The perpetrator always brandished a black semiautomatic 
pistol, which he held in his right hand.  Witnesses consistently 
described the perpetrator as a light-skinned Black or Hispanic 
male, approximately six feet, two inches tall, with a medium to 
thin build, dressed in a black hooded jacket, dark-colored 
 
16 The affidavit in support of the second warrant did not 
rely on any evidence obtained pursuant to the first warrant.  
Accordingly, suppression of the evidence from the first warrant 
would have no bearing on the admissibility of the evidence 
obtained pursuant to the second warrant.  See Commonwealth v. 
Tyree, 455 Mass. 676, 692 (2010). 
37 
 
pants, black gloves, black shoes, and a black or red mask.  In 
addition, on two occasions, surveillance footage showed a hole 
or a light-colored blemish on the robber's jacket.  
Collectively, this evidence provided a substantial basis to 
believe, see Escalera, 462 Mass. at 642, that the same 
individual had committed all of the offenses, see Commonwealth 
v. Marrero, 427 Mass. 65, 71-72 (1998), quoting Commonwealth v. 
Cordle, 404 Mass. 733, 740 (1989), S.C., 412 Mass. 172 (1992) 
("Although the circumstances of the . . . offenses were not 
identical, we think they were sufficiently similar to justify 
the inference that they were the product of the same mind" 
[alterations in original]). 
 
The second warrant affidavit also described evidence 
indicating that a suspected coventurer had acted as a getaway 
driver in at least three of the offenses under investigation.  
The robberies took place from two to eleven miles apart, and 
some of the locations were not near any public transportation.  
On October 4, 2018, the store clerk saw the perpetrator enter 
the passenger's side of a dark-colored sedan, without removing 
his mask, before quickly departing the scene.  On October 6, 
2018, a surveillance camera recorded video footage of a dark-
colored sedan or coupe traveling at a high rate of speed along 
the perpetrator's path of flight, as recorded by a separate 
surveillance camera.  Moreover, on October 31, 2018, police 
38 
 
canines detected the perpetrator's scent along his reported 
flight path, but the scent ended abruptly in a public area with 
no nearby public transportation, which could have indicated that 
the perpetrator entered a vehicle.  See Wilkerson, 486 Mass. 
at 172 (considering existence of and coordination with 
coventurer in finding probable cause to obtain CSLI). 
 
The search warrant affidavit also described facts 
suggesting some reason to believe that the defendant and a 
coventurer had communicated with one another from a distance, 
either prior to or after the commission of the offense.  The 
detective seeking the search warrant averred that, based on his 
experience and training, violent crimes such as those at issue 
often require some level of coordination amongst coventurers.  
See Holley, 478 Mass. at 522 (statement that particular crime 
often involves coordination among codefendants by cellular 
telephone was considered as one factor in probable cause 
analysis).  This coordination could have taken place while the 
perpetrators were apart; the robber appeared to travel some 
distance on foot prior to or after most of the robberies, and 
therefore was at least temporarily separated from the getaway 
driver.  The evidence that the perpetrator and the coventurer 
communicated from a distance, when combined with the affiant's 
statements about the over-all ubiquity of cellular telephones, 
provided reasonable grounds to believe that the robber and the 
39 
 
getaway driver had used cellular telephones to communicate.  See 
Commonwealth v. Almonor, 482 Mass. 35, 45 (2019), quoting 
Augustine I, 467 Mass. at 245-246 (cellular telephones "exist as 
'almost permanent attachments to [their users'] bodies'" and 
"physically accompany their users everywhere"). 
 
Because there was reason to believe that the perpetrator 
used a cellular telephone to communicate with a coventurer 
around the time of the offenses, there also was probable cause 
to believe that either the perpetrator's telephone or the 
coventurer's telephone would have produced telephone call CSLI 
that would appear in the requested tower dumps, and likely in 
more than one of the tower dumps.  This CSLI, in turn, would 
enable investigators to isolate potential suspects by 
determining which, if any, individuals had been near the scene 
of two or more of the offenses.  See Hobbs, 482 Mass. at 546 
(location of cellular telephone as recorded by CSLI can be 
"reasonably expected to be the location of the person possessing 
the cell phone").  Accordingly, the second warrant affidavit was 
supported by probable cause. 
 
B.  First warrant.  The affidavit in support of the first 
warrant, much like the affidavit in support of the second 
warrant, outlined significant similarities amongst the offenses 
then under investigation, and therefore afforded a substantial 
basis to believe that the offenses had been committed by the 
40 
 
same individual.  Additionally, the affidavit demonstrated 
reason to believe that the perpetrator had been, at least 
occasionally, assisted by a coventurer. 
 
The first warrant affidavit did not, however, set forth any 
particularized information that the perpetrator or the 
coventurer owned a cellular telephone or communicated with one 
another from a distance.  Compare Commonwealth v. Louis, 487 
Mass. 759, 765 (2021) (evidence showed that suspect 
"communicated with another robbery suspect via cell phone on the 
date of the murder"); Hobbs, 482 Mass. at 547 (affidavit for 
targeted CSLI must show that "suspect was known to own or use a 
particular cell phone").  Moreover, the first warrant affidavit 
did not discuss the need for coventurers to communicate when 
committing a robbery, nor did it point to any evidence that the 
perpetrator and the coventurer had been separated during the 
commission of the crime such that they would have had to 
communicate from a distance. 
 
Thus, the only ground in the first affidavit upon which to 
conclude that the perpetrator had possessed or used a cellular 
telephone to aid in accomplishing the crimes was the affiant 
officer's statement that "it is very common for a person to have 
a cellular telephone with them at all times."  See Commonwealth 
v. Rosetti, 349 Mass. 626, 632 (1965) (probable cause must be 
based on particularized facts, not "simply general 
41 
 
conclusions").  Therefore, the evidence obtained pursuant to the 
first warrant must be suppressed.  See Commonwealth v. Andre, 
484 Mass. 403, 408 (2020). 
 
ii.  Particularity.17  The defendant also argues that the 
search here was unreasonable because the search warrants 
themselves lacked particularity, and therefore were 
unconstitutional general warrants.  He maintains that, if the 
search of the CSLI was a search in the constitutional sense with 
respect to him, it necessarily follows that everyone whose CSLI 
was contained in the tower dumps also was searched.  This would 
render the warrants unconstitutional general warrants because 
they permitted law enforcement to search the CSLI of third 
parties who merely were present in the vicinities of the 
offenses being investigated, without any probable cause.  In the 
defendant's view, the only way to ensure that the scope of a 
search is sufficiently narrow is to require warrants for CSLI to 
identify the targeted suspect by name or telephone number. 
 
As the defendant emphasizes, art. 14 "require[s] that a 
search warrant describe with particularity the places to be 
searched and the items to be seized."  Commonwealth v. Perkins, 
478 Mass. 97, 106 (2017).  The particularity requirement "both 
 
17 Having concluded that the first warrant was not supported 
by probable cause, we need not consider whether it lacked 
particularity. 
42 
 
defines and limits the scope of the search and seizure."  
Commonwealth v. Pope, 354 Mass. 625, 629 (1968).  "The dual 
purposes of the particularity requirement are '(1) to protect 
individuals from general searches and (2) to provide the 
Commonwealth the opportunity to demonstrate, to a reviewing 
court, that the scope of the officers' authority to search was 
properly limited.'"  Holley, 478 Mass. at 524, quoting 
Commonwealth v. Valerio, 449 Mass. 562, 566-567 (2007).  See 
Riley v. California, 573 U.S. 373, 403 (2014) (general searches 
"allowed British officers to rummage through homes in an 
unrestrained search for evidence of criminal activity").  To 
this end, a warrant must describe the object of the search with 
enough specificity that investigators can identify, with 
reasonable certainty, that which they are authorized to search, 
thus ensuring that they search only those items for which 
probable cause exists.  See Commonwealth v. Treadwell, 402 Mass. 
355, 359 (1988). 
 
The precise degree of particularity required "necessarily 
var[ies] according to the circumstances and the type of items 
involved."  See Commonwealth v. Freiberg, 405 Mass. 282, 298, 
cert. denied, 493 U.S. 940 (1989), quoting United States v. 
Johnson, 541 F.2d 1311, 1314 (8th Cir. 1976).  More generality 
may be tolerated where a more precise description would be 
impracticable.  See, e.g., Henley, 488 Mass. at 119 (warrant for 
43 
 
search of contents of cellular telephone need not particularly 
identify specific electronic file to be searched "where officers 
had no knowledge of where on the cell phone evidence might be 
located, or in what format, but specifically identified the type 
of evidence sought"); Commonwealth v. McDermott, 448 Mass. 750, 
775, cert. denied, 552 U.S. 910 (2007) (warrant permitting 
search of computer files relating to defendant's mental health 
did not lack particularity because "[t]he lack of further 
specificity was practical in the circumstances, and the mental 
health category was limited as much as possible in the 
circumstances"). 
 
We do not agree that all of the individuals whose CSLI was 
revealed by the tower dumps were subjected to a search in the 
constitutional sense.  The defendant's reasonable expectation of 
privacy was invaded not simply by law enforcement's possession 
of his anonymized CSLI, but also by the investigating officers' 
possession and analysis of that CSLI, the aggregate of which 
provided investigators with a revealing mosaic of the 
defendant's private life.  See Henley, 488 Mass. at 109 (search 
inquiry under mosaic theory focuses on "the governmental action 
as a whole").  See also Kerr, supra at 320 (search occurs where 
government "collection and subsequent analysis" of data reveals 
mosaic [emphasis added]).  A cursory examination of anonymized 
CSLI would not permit investigators to infer the identity of any 
44 
 
given individual, where within the cell site's radius that 
person had been, or with whom he or she had associated; thus, 
such an examination would not intrude upon a reasonable 
expectation of privacy.  See Andresen v. Maryland, 427 U.S. 463, 
482 n.11 (1976); McCarthy, 484 Mass. at 504.  Only those 
individuals whose CSLI was subject to further analysis -- such 
as the defendant -- were subject to a search within the meaning 
of art. 14.  The question, then, becomes whether the second 
warrant sufficiently limited the set of telephone numbers and 
their associated CSLI that investigating officers were permitted 
to analyze, and therefore to search. 
 
As the defendant maintains, the scope of the search 
authorized by the warrant, on its face, is not entirely clear.  
Under "property to be searched," the warrant lists the "records 
and information associated with the cellular telephone 
towers/sites ('Cell Towers/Sites') that provided cellular 
service" in the vicinity of the crimes during the forty-minute 
period surrounding each offense.  With respect to "particular 
items to be seized," the warrant identifies the categories of 
information that the service provider must disclose, including, 
inter alia, the telephone number of the connecting cellular 
telephone and the sector of the cell site providing service to 
each connecting telephone.  Thus, if read in isolation, the 
warrant would permit investigators to analyze, without 
45 
 
limitation, any and all CSLI in the tower dumps.  Investigators 
permissibly could select any telephone number from among the 
50,000 provided and thereafter conduct a search by determining 
the identity of that individual, his or her location, and with 
whom he or she had been communicating, all without even an iota 
of suspicion.  Judicial authorization of such "general 
exploratory rummaging" undoubtedly would violate the 
particularity requirements of art. 14.  See Balicki, 436 Mass. 
at 7. 
 
Any deficiencies in the warrant itself, however, were 
remedied by the supporting affidavit, which adequately limited 
the scope of the search.18  See Commonwealth v. Dorelas, 473 
Mass. 496, 499 n.3 (2016) (although warrant lacked particularity 
on its face, search was permissible because affidavit limited 
scope of search).  The supporting affidavit explained that 
investigators sought to obtain the tower dumps in order "to 
identify and/or verify commonalities within [the] requested 
records."  Thus, police were permitted to isolate and analyze 
the CSLI of those telephone numbers that appeared in two or more 
 
18 A supporting affidavit can remedy a particularity defect 
in a warrant where (1) the warrant makes "specific reference to 
the affidavit" and (2) the officer who submitted the affidavit 
in support of the warrant was "one of the [officers] executing 
the warrant."  See Commonwealth v. Todisco, 363 Mass. 445, 450 
(1973).  See also E.B. Cypher, Criminal Practice and Procedure 
§ 5:101 (4th ed. 2021). 
46 
 
tower dumps, but no others.  Otherwise put, because the warrant 
authorized the search of only a narrow subset of the CSLI, for 
purposes of identifying a common suspect, it was sufficiently 
particular.19 
 
As the scope of the search was limited in this manner, that 
the warrant did not identify a suspect by name or telephone 
number did not render it insufficiently particular.  Unlike an 
arrest warrant, a search warrant "need not identify a specific 
criminal suspect -- although frequently it does."  Commonwealth 
v. Martinez, 476 Mass. 410, 419 (2017).  See Commonwealth v. 
Mora, 477 Mass. 399, 404 (2017) ("it is not necessary for the 
[warrant] application to identify a suspect").  "[S]earch 
warrants are often employed early in an investigation, perhaps 
before the identity of any likely criminal and certainly before 
all the perpetrators are or could be known."  Zurcher v. 
Stanford Daily, 436 U.S. 547, 561 (1978).  Requiring police to 
identify a presently unknown suspect by name "would unreasonably 
thwart the ability of the police to investigate a crime."  See 
 
19 The scope of the search was further limited because the 
warrant permitted investigators to obtain data only for brief 
periods of time (measured in minutes) surrounding the commission 
of the offenses.  See Commonwealth v. Hobbs, 482 Mass. 538, 546, 
549 (2019) (duration of search of targeted CSLI must be limited 
to period of time bearing sufficient nexus to crime under 
investigation); Commonwealth v. Dorelas, 473 Mass. 496, 503 
(2016) (search of electronically stored information must be 
limited to electronic files where evidence of crime "may 
reasonably be found"). 
47 
 
Freiberg, 405 Mass. at 299.  Although limiting a search of CSLI 
to an identified suspect might be the better practice where 
possible, it is not required where, as here, the suspect's 
identity is unknown and the scope of the search is appropriately 
limited through other means.  Compare id. at 299-300 (warrant 
permitting seizure of "instrument[s] used in crime" was 
sufficiently particular because "the exact characteristics of 
[the instruments] were not known to [police]" and warrant 
affidavit "made it reasonably clear that the 'instrumentalities' 
sought were related to a crime of violence"), with Commonwealth 
v. Taylor, 383 Mass. 272, 276 (1981) (warrant was not 
sufficiently particular where "the particularization was 
available but was not used in the warrant"). 
 
c.  Prospective limits on tower dump warrants.  General 
Laws c. 211, § 3, grants this court "general superintendence of 
the administration of all courts of inferior jurisdiction."  
Under this authority, we may "impose requirements (by order, 
rule or opinion) that go beyond constitutional mandates," 
Commonwealth v. O'Brien, 432 Mass. 578, 584 (2000), quoting 
Commonwealth v. Bastarache, 382 Mass. 86, 102 (1980), including 
those governing the issuance and content of warrants, see, e.g., 
Preventative Med. Assocs., Inc. v. Commonwealth, 465 Mass. 810, 
821-822 (2013); Rodriques v. Furtado, 410 Mass. 878, 888 (1991).  
Although this power "is to be used sparingly," it appropriately 
48 
 
may be exercised "in exceptional circumstances and where 
necessary to protect substantive rights in the absence of an 
alternative, effective remedy" (citation omitted).  MacDougall 
v. Commonwealth, 447 Mass. 505, 510 (2006). 
 
While the decision we reach today is grounded in individual 
rights protected by art. 14, we recognize the potential 
invasions of privacy that could befall those innocent and 
uninvolved third parties whose CSLI is revealed once an 
application for a search warrant is allowed.  See generally 
Owsley, supra at 44.  Unlike defendants in criminal cases, these 
individuals may never know that their CSLI was provided to law 
enforcement, let alone be able to exercise any sort of control 
or oversight over how their data is used.  See id. at 46.  Such 
a situation presents far too great a risk of unwarranted 
invasions of privacy, whether intentional or inadvertent, 
malicious or innocent.  Cf. Preventative Med. Assocs., Inc., 465 
Mass. at 821-822 (exercise of superintendence power was 
warranted given risk of irreparable invasion of privacy). 
 
Accordingly, in all future cases, only a judge may issue a 
search warrant for tower dumps.  See id. at 822 ("as an exercise 
of our supervisory powers, we shall require in all future cases 
that only a Superior Court judge may issue a search warrant 
seeking e-mails of a criminal defendant under indictment"); 
Rodriques, 410 Mass. at 888 ("under the exercise of our general 
49 
 
superintendence powers, we shall deem a warrant authorizing the 
search of a body cavity to be invalid unless issued by the 
authority of a judge"); G. L. c. 272, § 99 F 1 ("warrant to 
intercept wire or oral communications" must be issued by 
Superior Court judge). 
 
The warrant must include protocols for the prompt and 
permanent disposal of any and all data that does not fit within 
the object of the search following the conclusion of the 
prosecution.  See Matter of the Application of the U.S.A. for an 
Order Pursuant to 18 U.S.C. §§ 2703(c) & 2703(d) Directing AT&T, 
Spring/Nextel, T-Mobile, Metro PCS & Verizon Wireless to 
Disclose Cell Tower Log Info., 42 F. Supp. 3d 511, 519 (S.D.N.Y. 
2014) (warrant application for tower dump must "outline[] a 
protocol to address how the Government will handle the private 
information of innocent third-parties whose data is retrieved"); 
Matters of the Search of Cellular Tel. Towers, 945 F. Supp. 2d 
769, 771 (S.D. Tex. 2013) ("the Government is ordered to return 
any and all original records and copies . . . to the Provider, 
which are determined to be not relevant to the Investigative 
Agency's investigation"); Matter of the Application of the 
U.S.A. for an Order Pursuant to 18 U.S.C. § 2703(d) Directing 
Providers to Provide Historical Cell Site Location Records, 930 
F. Supp. 2d 698, 702 (S.D. Tex. 2012) (warrant for tower dump 
must include protocol for handling of "data related to innocent 
50 
 
people who are not the target of the criminal investigation").  
See also G. L. c. 276, § 3 ("all property seized [pursuant to a 
search warrant] shall be restored to the owners thereof" "[a]s 
soon as may be"). 
 
d.  Retroactivity.  Because we are announcing a 
constitutionally mandated requirement for the first time, we 
also must consider whether our holding is to be applied 
retroactively.  The retroactivity of a constitutional rule of 
criminal procedure turns on whether the rule is "new" or "old."  
Commonwealth v. Ashford, 486 Mass. 450, 457 (2020).  "[A] case 
announces a new rule if the result was not dictated by 
precedent" (emphasis in original).  Commonwealth v. Bray, 407 
Mass. 296, 301 (1990), quoting Teague v. Lane, 489 U.S. 288, 301 
(1989).  "[A] holding is not so dictated . . . unless it would 
have been 'apparent to all reasonable jurists.'"  Chaidez v. 
United States, 568 U.S. 342, 347 (2013), quoting Lambrix v. 
Singletary, 520 U.S. 518, 527-528 (1997). 
 
The rule we announce today undoubtedly is new; we are 
unaware of any existing statute or prior judicial opinion that 
would have obligated investigators to obtain a search warrant 
before acquiring or analyzing tower dumps.  See Augustine I, 467 
Mass. at 257.  Accordingly, our holding applies prospectively 
and to those cases that are active or pending on direct review 
51 
 
on the date of issuance of the rescript in this case.20  See 
Diatchenko v. District Attorney for the Suffolk Dist., 466 Mass. 
655, 664 (2013), S.C., 471 Mass. 12 (2015). 
 
3.  Conclusion.  The Commonwealth's actions in this case 
intruded upon the defendant's reasonable expectation of privacy 
and therefore effectuated a search under art. 14.  Nonetheless, 
because the second warrant was sufficiently particular and 
supported by probable cause, the evidence obtained pursuant to 
the second warrant need not be suppressed.  All evidence 
stemming from the tower dumps provided pursuant to the first 
warrant, however, must be suppressed because the warrant was not 
supported by probable cause.  Our decision is prospective, and 
also applies to those cases that are active or pending on direct 
review on the date of issuance of the rescript in this case.  
Henceforth, before acquiring and analyzing a series of tower 
dumps, the Commonwealth must obtain a warrant from a judge.  
Before issuing the requested warrant, the judge must ensure that 
 
20 New rules apply retroactively if the rule "is 
'substantive,' defining a class of conduct that cannot be deemed 
criminal, or prohibiting imposition of a type of punishment on a 
particular class of defendants" or "establishes a 'watershed' 
rule of criminal procedure that is 'implicit in the concept of 
ordered liberty,' implicating the fundamental fairness of the 
proceeding."  Augustine I, 467 Mass. at 257 n.39, quoting 
Diatchenko v. District Attorney for the Suffolk Dist., 466 Mass. 
655, 665 (2013), S.C., 471 Mass. 12 (2015). 
52 
 
it provides a protocol for the disposal of any data that falls 
outside the scope of the search. 
 
 
 
 
 
 
 
So ordered.