Case Title: Commonwealth v. McCarthy

Citation: 

Docket Number: SJC-12750

State: massachusetts

Court: Massachusetts Supreme Court

Date: 2020-04-16T00:00:00Z

Document:
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SJC-12750 
 
COMMONWEALTH  vs.  JASON J. McCARTHY. 
 
 
 
Barnstable.     October 2, 2019. - April 16, 2020. 
 
Present (Sitting at Barnstable):  Gants, C.J., Lenk, Gaziano, 
Lowy, Budd, Cypher, & Kafker, JJ. 
 
 
Privacy.  Constitutional Law, Privacy, Search and seizure, 
Standing, Admissions and confessions, Voluntariness of 
statement.  Search and Seizure, Expectation of privacy, 
Electronic surveillance, Motor vehicle.  Practice, 
Criminal, Motion to suppress, Standing, Admissions and 
confessions, Voluntariness of statement.  Evidence, 
Admissions and confessions, Voluntariness of statement. 
 
 
 
 
Indictment found and returned in the Superior Court 
Department on August 31, 2017. 
 
 
Pretrial motions to suppress evidence were heard by Robert 
C. Rufo, J. 
 
 
An application for leave to prosecute an interlocutory 
appeal was allowed by Kafker, J., in the Supreme Judicial Court 
for the county of Suffolk, and the case was reported by him. 
 
 
 
Paul A. Bogosian for the defendant. 
 
Elizabeth A. Sweeney, Assistant District Attorney, for the 
Commonwealth. 
 
David R. Fox, for Digital Recognition Network, Inc., amicus 
curiae, submitted a brief. 
2 
 
 
Matthew Spurlock & David Rassoul Rangaviz, Committee for 
Public Counsel Services, Ashley Gorski, of New York, Jennifer 
Lynch & Andrew Crocker, of California, Jessie J. Rossman, 
Matthew R. Segal, & Nathan Freed Wessler, for American Civil 
Liberties Union & others, amici curiae, submitted a brief. 
 
 
 
GAZIANO, J.  While investigating the defendant on suspicion 
of drug distribution, police used automatic license plate 
readers (ALPRs) on the Bourne and Sagamore bridges to track his 
movements.  They accessed historical data, which revealed the 
number of times he had crossed the bridges over a three-month 
period, and also received real-time alerts, one of which led to 
his arrest.  We must determine whether the use of ALPR 
technology in this case constituted a search under the Fourth 
Amendment to the United States Constitution or under art. 14 of 
the Massachusetts Declaration of Rights. 
 
We conclude that, while the defendant has a 
constitutionally protected expectation of privacy in the whole 
of his public movements, an interest which potentially could be 
implicated by the widespread use of ALPRs, that interest is not 
invaded by the limited extent and use of ALPR data in this case. 
 
1.  Background.  We draw the following from the facts found 
by the motion judge, reserving some facts for later discussion. 
 
a.  ALPR systems.  Automatic license plate readers are 
cameras combined with software that allows them to identify and 
"read" license plates on passing vehicles.  When an ALPR 
3 
 
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.  In Massachusetts, cameras owned and 
maintained by the State police feed this information into a 
database maintained by the Executive Office of Public Safety and 
Security (EOPSS).1  At some point in 2015, the State police 
installed fixed camera readers on both sides of the Sagamore and 
Bourne bridges.  While these cameras are not infallible,2 they 
essentially create a comprehensive record of vehicles traveling 
onto or off of the Cape. 
 
ALPR systems produce two related types of information:  
real-time alerts and historical data.  First, individuals with 
user credentials can log onto the ALPR system, enter license 
plate numbers onto a "hot list," and choose users to be notified 
about any new "hits" for that plate number.  If a camera in the 
ALPR system detects a license plate that matches a number on the 
hot list, the system sends an electronic mail message or text 
                                                          
 
 
1 According to the amici, private companies also own and 
operate automatic license plate reader (ALPR) cameras and share 
that data with law enforcement, as do individual homeowners.  
Federal and State law enforcement offices, in turn, may share 
data with each other. 
 
 
2 A testifying expert identified weather conditions, warped 
or obscured plates, and particularly bad lighting conditions as 
factors that might result in the ALPR failing to read a 
particular license plate. 
4 
 
message to the specified officers.  Alert recipients receive an 
image of the plate, along with the date, time, location, and 
direction of travel.  Second, users can search by license plate 
number for any historical matches stored in the database.  EOPSS 
currently has a one-year retention policy for ALPR data.3 
 
The Barnstable police department has adopted the State 
police general order setting out various regulations for the use 
of ALPR information.  See State police General Order No. TRF-11 
(July 22, 2014) (Order TRF-11).4 
 
b.  The investigation.  Through surveillance, several 
"controlled buys," and information from four confidential 
informants, the Barnstable police developed substantial evidence 
that a codefendant in this case was distributing heroin from his 
residence.  During that surveillance, they observed a black 
Hyundai vehicle appear briefly at the codefendant's residence.  
                                                          
 
 
3 Aside from any changes to retention policy or failure to 
implement purging according to the policy, electronic mail 
messages sent after a real-time alert may be retained longer 
than one year, indeed indefinitely, on the recipient's server, 
as was the case here. 
 
 
4 State police General Order No. TRF-11 (July 22, 2014) 
(Order TRF-11) requires, inter alia, that only trained, 
specially designated users may access the system; that the "ALPR 
System and information shall be . . . [a]ccessed and used only 
for official and legitimate law enforcement purpose"; and that 
prior to initiating a stop based on an ALPR hit or alert, the 
officer must verify visually the alphanumeric characters on the 
license plate and verify the status of the plate through one of 
various databases. 
5 
 
After further surveillance, and a tip from a confidential 
informant, police observed the defendant driving the same 
vehicle, and they began to suspect that he was supplying heroin 
to his codefendant. 
 
On February 1, 2017, Barnstable police added the license 
plate number of the black Hyundai to the ALPR hot list, and 
specified officers to be notified when it was detected crossing 
the Bourne or Sagamore bridges.  On February 8, 2017, several 
police officers received an alert that the Hyundai had been 
driven over the Sagamore Bridge onto Cape Cod.  Officers 
subsequently traveled to the codefendant's house and then 
followed him to Shallow Pond Road in Centerville.  At the same 
time, another officer found the defendant after he drove onto 
the Cape and followed him to Shallow Pond Road.  The officers 
watched the defendant and the codefendant meet, but no physical 
exchange was observed.  Both vehicles left after approximately 
thirty seconds. 
 
Police also generated a spreadsheet indicating every time 
that the Hyundai had passed over the Bourne and Sagamore bridges 
between December 1, 2016, and February 12, 2017.  The 
spreadsheet contained the dates, times, directions, and specific 
lanes that the Hyundai had traveled on the bridges.  The ALPR 
spreadsheet showed that the vehicle traveled onto Cape Cod on 
eight days in February, twenty-one days in January, and nineteen 
6 
 
days in December.  On multiple of these days, the defendant made 
more than one trip on the same day.  This appeared consistent 
with the police theory that the defendant routinely was bringing 
heroin onto the Cape for distribution by his codefendant. 
 
On February 22, 2017, Barnstable police received another 
alert that the Hyundai had traveled over the Sagamore Bridge 
onto Cape Cod.  Police again followed both the defendant and the 
codefendant as they drove to Shallow Pond Road.  The officers 
observed a meeting, but did not see an exchange of objects.  
Both vehicles departed thirty seconds later.  This time, police 
stopped both vehicles on suspicion that a drug transaction had 
taken place. 
 
After stopping the codefendant, police handcuffed him, read 
him his Miranda rights, and questioned him at the side of the 
road.  He made incriminating statements, and officers found 
heroin on his person.  Police also ordered the defendant out of 
his vehicle, handcuffed him, and read him his Miranda rights.  
The motion judge found that the defendant was under arrest at 
the moment that he was ordered out of the Hyundai and 
handcuffed. 
 
At the police station, the defendant waived his Miranda 
rights and made various incriminating statements.  Officers also 
seized two cellular telephones and United States currency from 
the defendant's person.  The defendant's brother brought more 
7 
 
money to pay the bail for the defendant, but police seized 
almost all of the cash on the belief that it was the proceeds of 
illegal drug activity. 
 
The defendant filed motions to suppress the ALPR data and 
the fruits of the arrest.  A Superior Court judge held an 
evidentiary hearing and then denied the motions.  The defendant 
then filed an application for leave to pursue an interlocutory 
appeal in the county court, pursuant to Mass. R. Crim. 
P. 15 (a) (2), as appearing in 474 Mass. 1501 (2016); the single 
justice allowed the appeal to proceed in this court. 
 
2.  Discussion.  "In reviewing a decision on a motion to 
suppress, we accept the judge's subsidiary findings absent clear 
error but conduct an independent review of [the] ultimate 
findings and conclusions of law" (quotations and citation 
omitted).  Commonwealth v. Jones-Pannell, 472 Mass. 429, 431 
(2015).  Here, reviewing the judge's conclusions of law requires 
us to determine, among other things, whether the use of ALPR 
technology by police constitutes a search under the Fourth 
Amendment or art. 14. 
 
a.  ALPRs and constitutional search protections.  Under 
both the Fourth Amendment and art. 14, a search implicates 
constitutional protections when the government "intrudes on a 
person's reasonable expectation of privacy" (citation omitted).  
Commonwealth v. Almonor, 482 Mass. 35, 40 (2019).  "An 
8 
 
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" (quotations and 
citation omitted).5  Commonwealth v. Johnson, 481 Mass. 710, 715, 
cert. denied, 140 S. Ct. 247 (2019).  See Katz v. United States, 
389 U.S. 347, 361 (1967) (Harlan, J., concurring). 
 
The constitutional jurisprudence governing the 
technological surveillance of public space has developed rapidly 
in the last decade.  To place the current situation in the 
proper context, it is necessary to review these developments and 
their underlying reasoning at some length. 
 
i.  Expectations of privacy and technology.  As this court 
and the United States Supreme Court interpret society's 
reasonable expectations of privacy over time, the courts' 
overarching goal is to "assure [the] preservation of that degree 
                                                          
 
 
5 In this case, the judge did not find explicitly that the 
defendant had manifested a subjective expectation of privacy.  
We infer from the undisputed record, however, that the defendant 
manifested a subjective expectation of privacy in his location 
by choosing to meet his codefendant in a quiet residential area.  
See Commonwealth v. Fulgiam, 477 Mass. 20, 33, cert. denied, 138 
S. Ct. 330 (2017) (concluding that subjective prong was 
satisfied based on record).  See, e.g., United States v. Moore-
Bush, 381 F. Supp. 3d 139, 143 (D. Mass. 2019) ("the Court 
infers from their choice of neighborhood that they subjectively 
expected that their and their houseguests' comings and goings 
over the course of eight months would not be surreptitiously 
surveilled"). 
9 
 
of privacy against government that existed when the Fourth 
Amendment [and art. 14 were] adopted."  Almonor, 482 Mass. at 54 
(Lenk, J., concurring), quoting Carpenter v. United States, 138 
S. Ct. 2206, 2214 (2018).  We have recognized the difficulty of 
this enterprise as developing technology places "extraordinarily 
powerful surveillance tool[s]" in the hands of police.  Almonor, 
supra at 46.  See Johnson, 481 Mass. at 716.  While 
acknowledging the usefulness of these tools for crime detection, 
"both this court and the United States Supreme Court have been 
careful to guard against the 'power of technology to shrink the 
realm of guaranteed privacy' by emphasizing that privacy rights 
'cannot be left at the mercy of advancing technology but rather 
must be preserved and protected as new technologies are adopted 
and applied by law enforcement.'"  Almonor, supra at 41, quoting 
Johnson, supra.  See Kyllo v. United States, 533 U.S. 27, 34 
(2001).  See also Olmstead v. United States, 277 U.S. 438, 473 
(1928) (Brandeis, J., dissenting) (noting that courts must be 
vigilant to guard against "[s]ubtler and more far-reaching means 
of invading privacy [that] have become available to the 
government"). 
 
Like the Supreme Court, this court is guided "by historical 
understandings of what was deemed an unreasonable search and 
seizure when [the Constitutions were] adopted."  See Almonor, 
482 Mass. at 43, citing Carpenter, 138 S. Ct. at 2214.  These 
10 
 
historical understandings include the basic purposes underlying 
the adoption of art. 14 and, later, the Fourth Amendment.  See 
Almonor, supra, quoting Jenkins v. Chief Justice of the Dist. 
Court Dep't, 416 Mass. 221, 229 (1993) ("we construe [art. 14] 
in light of the circumstances under which it was framed, the 
causes leading to its adoption, the imperfections hoped to be 
remedied, and the ends designed to be accomplished").  See also 
Carpenter, supra at 2213.  More specifically, we have recognized 
that the underlying purposes of both art. 14 and the Fourth 
Amendment are the need to "secure the privacies of life against 
arbitrary power," and to "place obstacles in the way of a too 
permeating police surveillance."  Almonor, supra at 53 (Lenk, 
J., concurring), quoting Carpenter, supra at 2214.  Both warrant 
further explanation in the context of emerging technology. 
 
A.  Arbitrary power.  The framers had first-hand experience 
with abuses of arbitrary power under British rule.  Our cases 
acknowledge that they wrote constitutional search protections in 
"response to the reviled 'general warrants' and 'writs of 
assistance' of the colonial era, which allowed British officers 
to rummage through homes in an unrestrained search for evidence 
of criminal activity."  See Carpenter, 138 S. Ct. at 2213, 
quoting Riley v. California, 573 U.S. 373, 403 (2014).  See also 
Commonwealth v. Blood, 400 Mass. 61, 71 (1987).  The 
surveillance implications of new technologies must be 
11 
 
scrutinized carefully, lest scientific advances give police 
surveillance powers akin to these general warrants.  Just as 
police are not permitted to rummage unrestrained through one's 
home, so too constitutional safeguards prevent warrantless 
rummaging through the complex digital trails and location 
records created merely by participating in modern society.  See, 
e.g., Almonor, 482 Mass. at 46 (police causing cellular 
telephone to reveal real-time location contravenes reasonable 
expectation of privacy); Commonwealth v. Augustine, 467 Mass. 
230, 255 (2014), S.C., 470 Mass. 837 (2015) (reasonable 
expectation of privacy exists in cellular site location 
information [CSLI]6).  See also Carpenter, supra at 2217 ("A 
person does not surrender all Fourth Amendment protection by 
venturing into the public sphere"). 
 
B.  Permeating police presence.  As the Supreme Court made 
clear in Carpenter, courts analyzing the constitutional 
implications of new surveillance technologies also should be 
guided by the founders' intention "to place obstacles in the way 
of a too permeating police surveillance."  Carpenter, 138 S. Ct. 
at 2214, quoting United States v. Di Re, 332 U.S. 581, 595 
                                                          
 
 
6 Cellular site location information "refers to a cellular 
telephone service record or records that contain information 
identifying the base station towers and sectors that receive 
transmissions from a [cellular] telephone" (citation omitted).  
Commonwealth v. Estabrook, 472 Mass. 852, 853 n.2 (2015). 
12 
 
(1948).  Specifically, both this court and the Supreme Court 
have recognized how advancing technology undercuts traditional 
checks on an overly pervasive police presence because it (1) is 
not limited by the same practical constraints that heretofore 
effectively have limited long-running surveillance, (2) proceeds 
surreptitiously, and (3) gives police access to categories of 
information previously unknowable. 
 
As Justice Alito wrote in Jones, "[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."  United States v. 
Jones, 565 U.S. 400, 429 (2012) (Alito, J., concurring).  The 
continuous, tireless, effortless, and absolute surveillance of 
the digital age contravenes expectations of privacy that are 
rooted in these historical and practical limitations.  For this 
reason, when the duration of digital surveillance drastically 
exceeds what would have been possible with traditional law 
enforcement methods, that surveillance constitutes a search 
under art. 14.  See, e.g., Augustine, 467 Mass. at 253. 
 
In addition, the surreptitious nature of digital 
surveillance removes a natural obstacle to too permeating a 
police presence by hiding the extent of that surveillance.  
Resource constraints aside, we imagine Massachusetts residents 
13 
 
would object were the police continuously to track every 
person's public movements by traditional surveillance methods, 
absent any suspicion at all.  Justice Sotomayor summed up these 
first two concerns in a discussion of global positioning system 
(GPS)7 monitoring:  "because [it] is cheap in comparison to 
conventional surveillance techniques and, by design, proceeds 
surreptitiously, it evades the ordinary checks that constrain 
abusive law enforcement practices:  'limited police resources 
and community hostility'" (citation omitted).  Jones, 565 U.S. 
at 415–416 (Sotomayor, J., concurring). 
 
Finally, new surveillance techniques risk creating too 
permeating a police presence by giving police access to "a 
category of information otherwise unknowable."  Carpenter, 138 
S. Ct. at 2218.  For example, with CSLI data "the Government can 
now travel back in time to retrace a person's whereabouts . . . 
[and] police need not even know in advance whether they want to 
follow a particular individual, or when.  Whoever the suspect 
turns out to be, he has effectively been tailed every moment of 
every day for five years . . . ."  Id.  See Augustine, 467 Mass. 
                                                          
 
 
7 A global positioning system (GPS) tracking system "allows 
police to monitor and record the location of a vehicle [or an 
individual] without the [target]'s knowledge" by ascertaining 
the target's location via communication with satellites, and 
then transmitting that location to a computer system that stores 
it electronically.  Commonwealth v. Connolly, 454 Mass. 808, 812 
(2009). 
14 
 
at 254.  Likewise, in Almonor, 482 Mass. at 46, this court 
considered the capability of police to "ping" a cellular 
telephone, causing it to reveal its real-time location data, and 
observed that "[t]his extraordinarily powerful surveillance tool 
finds no analog in the traditional surveillance methods of law 
enforcement." 
 
These historical understandings inform our analysis as we 
apply the test that originated more than fifty years ago in 
Katz, 389 U.S. at 361 (Harlan, J., concurring), to determine 
whether the collection and use of ALPR data constitutes a 
search. 
 
ii.  Searches in public.  This founding-era guidance has 
aided courts, even as technological advances in the surveillance 
of public space have posed difficult questions to courts under 
the "reasonable expectation of privacy" framework established in 
Katz.  The tension derives from two contrasting sentences 
contained in Katz itself.  First, Katz states that "[w]hat a 
person knowingly exposes to the public, even in his own home or 
office, is not a subject of Fourth Amendment protection."  Katz, 
389 U.S. at 351.  For this reason, "[w]hether an expectation of 
privacy is reasonable depends in large part upon whether that 
expectation relates to information that has been exposed to the 
public" (alteration, quotation, and citation omitted).  United 
States v. Maynard, 615 F.3d 544, 558 (D.C. Cir. 2010), aff'd in 
15 
 
part sub nom. Jones, 565 U.S. 400.  On the other hand, "[a] 
person does not surrender all Fourth Amendment protection by 
venturing into the public sphere."  Carpenter, 138 S. Ct. 
at 2217.  For "what [someone] seeks to preserve as private, even 
in an area accessible to the public, may be constitutionally 
protected."  Katz, supra.  See id. at 354 (constitutionally 
protected privacy interest in contents of telephone conversation 
made from public telephone booth).  In short, while the Fourth 
Amendment and art. 14 "protect[] people, not places," whether 
something is knowingly exposed to the public remains a 
touchstone in determining the reasonableness of a person's 
expectation of privacy.  Id. at 351.  See Augustine, 467 Mass. 
at 252; Commonwealth v. Billings, 42 Mass. App. Ct. 261, 265 
(1997) (listing constitutional nonsearches based on knowing 
exposure principle). 
 
A.  What is knowingly exposed.  Under this doctrine, police 
observation of the exterior of an automobile is not a search 
because it is "knowingly exposed."  See New York v. Class, 475 
U.S. 106, 114 (1986) ("The exterior of a car, of course, is 
thrust into the public eye, and thus to examine it does not 
constitute a 'search'").  In Massachusetts, this reasoning 
extends quite naturally to license plates.  In Commonwealth v. 
Starr, 55 Mass. App. Ct. 590, 591 (2001), a police officer saw a 
license plate on an automobile, located the plate number in a 
16 
 
police database, and stopped the vehicle because the plates were 
registered to a different vehicle.  Relying on the knowing 
exposure principle of Katz, the court held that the defendant 
had no reasonable expectation of privacy that would prevent an 
officer from examining his license plate.  Starr, supra at 593-
594.8 
 
In United States v. Knotts, 460 U.S. 276, 285 (1983), the 
Supreme Court applied the logic of "what is knowingly exposed" 
to sanction the warrantless use of a radio "beeper"9 to assist 
police in tracking a vehicle on a single journey. 
"A person traveling in an automobile on public 
thoroughfares has no reasonable expectation of privacy 
in his movements from one place to another.  When [the 
codefendant] traveled over the public streets he 
voluntarily conveyed to anyone who wanted to look the 
fact that he was traveling over particular roads in a 
particular direction, the fact of whatever stops he 
made, and the fact of his final destination when he 
exited from public roads onto private property." 
Id. at 281–282.  In so holding, the Knotts Court dismissed the 
defendant's claim that, should he lose his case, "twenty-four 
                                                          
 
 
8 Massachusetts requires that license plates be "displayed 
conspicuously," G. L. c. 90, § 6, and the failure to do so can 
result in fines or imprisonment, see G. L. c. 90, § 23.  These 
requirements support the contention that there is no objectively 
reasonable expectation of privacy in a license plate number, the 
very purpose of which is to identify the vehicle to the 
government. 
 
 
9 "A beeper is a radio transmitter, usually battery 
operated, which emits periodic signals that can be picked up by 
a radio receiver."  United States v. Knotts, 460 U.S. 276, 277 
(1983). 
17 
 
hour surveillance of any citizen of this country will be 
possible, without judicial knowledge or supervision."  Id. 
at 283.  The court went on to note, however, that "if such 
dragnet-type law enforcement practices as respondent envisions 
should eventually occur, there will be time enough then to 
determine whether different constitutional principles may be 
applicable."  Id. at 284. 
 
In this distinction, we recognize precisely the question 
posed by this case:  whether Knotts, Starr, and the "knowing 
exposure" principle of Katz control, as the Commonwealth 
contends, or whether different constitutional principles apply, 
as the defendant argues.  To answer, we must look to those cases 
of emerging surveillance technology where we indeed have 
determined that different constitutional principles govern. 
 
B.  Mosaic theory.  When new technologies drastically 
expand police surveillance of public space, both the United 
States Supreme Court and this court have recognized a privacy 
interest in the whole of one's public movements.  See Carpenter, 
138 S. Ct. at 2217 ("individuals have a reasonable expectation 
of privacy in the whole of their physical movements"); Johnson, 
481 Mass. at 716; Augustine, 467 Mass. at 248-249; Commonwealth 
v. Rousseau, 465 Mass. 372, 382 (2013). 
 
The question first emerged in the context of a GPS device 
affixed to a suspect's vehicle.  We ultimately concluded, 
18 
 
consistent with Supreme Court precedent, that "the government's 
contemporaneous electronic monitoring of one's comings and 
goings in public places invades one's reasonable expectation of 
privacy."  Rousseau, 465 Mass. at 382.  Next, in cases 
addressing police access to CSLI, both this court and the 
Supreme Court reaffirmed the same principle -- that it is 
objectively reasonable for individuals to expect to be free from 
sustained electronic monitoring of their public movements.  See 
Augustine, 467 Mass. at 247-248.  See also Carpenter, 138 S. Ct. 
at 2219. 
 
Both courts reached these conclusions, in part, by 
distinguishing the relatively primitive beeper used in Knotts 
from the encyclopedic, effortless collection of CSLI and GPS 
data.  See Augustine, 467 Mass. at 252 ("There is no real 
question that the government, without securing a warrant, may 
use electronic devices to monitor an individual's movements in 
public to the extent that the same result could be achieved 
through visual surveillance" [emphasis added]).  See also 
Carpenter, 138 S. Ct. at 2215, 2218 (distinguishing 
"rudimentary" beeper used in Knotts to track single "discrete 
automotive journey" from use of CSLI, which achieves "near 
perfect surveillance, as if [the government] had attached an 
ankle monitor to the phone's user"). 
19 
 
 
Essentially, these cases articulate an aggregation 
principle for the technological surveillance of public conduct, 
sometimes referred to as the mosaic theory.10  When collected for 
a long enough period, "the cumulative nature of the information 
collected implicates a privacy interest on the part of the 
individual who is the target of the tracking."  Augustine, 467 
Mass. at 253.  See Jones, 565 U.S. at 416 (Sotomayor, J., 
concurring) ("when considering the existence of a reasonable 
societal expectation of privacy in the sum of one's public 
movements . . . I would ask whether people reasonably expect 
that their movements will be recorded and aggregated in a manner 
that enables the Government to ascertain, more or less at will, 
their political and religious beliefs, sexual habits, and so on" 
[emphasis added]).  A recent case in the United States District 
Court for the District of Massachusetts summarized the idea 
succinctly:  "Although these activities, taken one by one, may 
not give rise to a reasonable expectation of privacy . . . , the 
                                                          
 
 
10 See, e.g., Kerr, The Mosaic Theory of the Fourth 
Amendment, 111 Mich. L. Rev. 311, 320 (2012) ("The mosaic theory 
requires courts to apply the Fourth Amendment search doctrine to 
government conduct as a collective whole rather than in isolated 
steps.  Instead of asking if a particular act is a search, the 
mosaic theory asks whether a series of acts that are not 
searches in isolation amount to a search when considered as a 
group.  The mosaic theory is therefore premised on aggregation:  
it considers whether a set of nonsearches aggregated together 
amount to a search because their collection and subsequent 
analysis creates a revealing mosaic"). 
20 
 
Court aggregates their sum total for its analysis."  United 
States v. Moore-Bush, 381 F. Supp. 3d 139, 149 (D. Mass. 2019).  
As the analogy goes, the color of a single stone depicts little, 
but by stepping back one can see a complete mosaic. 
 
This aggregation principle or mosaic theory is wholly 
consistent with the statement in Katz, 389 U.S. at 351, that 
"[w]hat a person knowingly exposes to the public . . . is not a 
subject of Fourth Amendment protection," because the whole of 
one's movements, even if they are all individually public, are 
not knowingly exposed in the aggregate.  As the United States 
Court of Appeals for the District of Columbia Circuit explained: 
"the whole of a person's movements over the course of a 
month is not actually exposed to the public because 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 
that make up that person's hitherto private routine." 
Maynard, 615 F.3d at 560. 
 
A detailed account of a person's movements, drawn from 
electronic surveillance, encroaches upon a person's reasonable 
expectation of privacy because the whole reveals far more than 
the sum of the parts.  "The difference is not one of degree but 
of kind . . . ."  Id. at 562.  "Prolonged surveillance reveals 
types of information not revealed by short-term surveillance, 
21 
 
such as what a person does repeatedly, what he does not do, and 
what he does ensemble."  Id.  Aggregated location data reveals 
"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 of the pattern 
of our professional and avocational pursuits."  Commonwealth v. 
Connolly, 454 Mass. 808, 834 (2009) (Gants, J., concurring), 
quoting People v. Weaver, 12 N.Y.3d 433, 442 (2009). 
 
iii.  Constitutional implications of ALPRs.  With this 
theoretical foundation in mind, we turn to the central question 
of this case:  whether the use of ALPRs by the police invades an 
objective, reasonable expectation of privacy.  Or, more 
specifically, we must determine whether ALPRs produce a detailed 
enough picture of an individual's movements so as to infringe 
upon a reasonable expectation that the Commonwealth will not 
electronically monitor that person's comings and goings in 
public over a sustained period of time.  See, e.g., Augustine, 
467 Mass. at 247-248. 
 
A.  ALPRs under the mosaic theory.  In determining whether 
a reasonable expectation of privacy has been invaded, it is not 
the amount of data that the Commonwealth seeks to admit in 
evidence that counts, but, rather, the amount of data that the 
government collects or to which it gains access.  See 
Commonwealth v. Estabrook, 472 Mass. 852, 858-859 (2015), citing 
22 
 
Augustine, 467 Mass. at 254 ("in terms of reasonable expectation 
of privacy, the salient consideration is the length of time for 
which a person's CSLI is requested, not the time covered by the 
person's CSLI that the Commonwealth ultimately seeks to use as 
evidence at trial").  In Rousseau, 465 Mass. at 376, 382, we 
weighed the thirty-one days of GPS monitoring in the 
constitutional analysis, not the data that placed the vehicle 
near the suspected arsons on four specific dates.  Similarly, in 
Carpenter, 138 S. Ct. at 2212-2213, the relevant period was the 
127 days of CSLI data, not the data that placed the defendant 
near the robberies on four particular days.11  For this reason, 
our constitutional analysis ideally would consider every ALPR 
                                                          
 
 
11 Our holding in Commonwealth v. Johnson, 481 Mass. 710, 
722, cert. denied, 140 S. Ct. 247 (2019), is not to the 
contrary.  There, we determined that the imposition of GPS 
monitoring on a specific probationer was a search, but a 
reasonable one in the circumstances.  Id. at 720.  We then 
concluded that the subsequent examination of the probationer's 
location data by law enforcement was not a search, because the 
probationer had no reasonable expectation of privacy in his 
location; he knew he was wearing a GPS ankle monitor that was 
transmitting his location to the government.  See id. at 722-
725, 728.  As an ancillary rationale, we emphasized that the 
police only sought the defendant's location at the specific 
times of various robberies, thus minimizing the intrusion.  Id. 
at 727-728.  Throughout, we emphasized the importance of the 
individual's status as a probationer, contrasting his 
expectations of privacy with those of a nonprobationer.  Id. 
at 724 ("There is no question that the reasonableness of any 
expectations of privacy held by a probationer knowingly subject 
to GPS monitoring as a condition of probation is far different 
from the reasonableness of the expectations of privacy held by 
individuals who are surreptitiously tracked by law 
enforcement"). 
23 
 
record of a defendant's vehicle that had been stored and 
collected by the government up to the time of the defendant's 
arrest.  That information, however, is not in the record before 
us. 
 
With enough cameras in enough locations, the historic 
location data from an ALPR system in Massachusetts would invade 
a reasonable expectation of privacy and would constitute a 
search for constitutional purposes.  The one-year retention 
period indicated in the EOPSS retention policy certainly is long 
enough to warrant constitutional protection.  See Augustine, 467 
Mass. at 254–255 ("tracking of the defendant's movements [by 
CSLI] in the urban Boston area for two weeks was more than 
sufficient to intrude upon the defendant's expectation of 
privacy safeguarded by art. 14"); Rousseau, 465 Mass. at 382 
(thirty-one days of GPS monitoring was sufficient duration to 
conclude monitoring was search).  Like CSLI data, ALPRs allow 
the police to reconstruct people's past movements without 
knowing in advance who police are looking for, thus granting 
police access to "a category of information otherwise [and 
previously] unknowable."  See Carpenter, 138 S. Ct. at 2218.  
Like both CSLI and GPS data, ALPRs circumvent traditional 
constraints on police surveillance power by being cheap 
(relative to human surveillance) and surreptitious. 
24 
 
 
Of course, the constitutional question is not merely an 
exercise in counting cameras; the analysis should focus, 
ultimately, on the extent to which a substantial picture of the 
defendant's public movements are revealed by the surveillance.  
For that purpose, where the ALPRs are placed matters too.  ALPRs 
near constitutionally sensitive locations -- the home, a place 
of worship, etc. -- reveal more of an individual's life and 
associations than does an ALPR trained on an interstate highway.  
A network of ALPRs that surveils every residential side street 
paints a much more nuanced and invasive picture of a driver's 
life and public movements than one limited to major highways 
that open into innumerable possible destinations.  For while no 
ALPR network is likely to be as detailed in its surveillance as 
GPS or CSLI data, one well may be able to make many of the same 
inferences from ALPR data that implicate expressive and 
associative rights.12  See American Civ. Liberties Union Found. 
of S. Cal. v. Superior Court of Los Angeles County, 3 Cal. 5th 
                                                          
 
 
12 The International Association of Chiefs of Police has 
warned that collecting ALPR data from multiple sources creates 
the risk "that individuals will become more cautious in the 
exercise of their protected rights of expression, protest, 
association, and political participation because they consider 
themselves under constant surveillance."  International 
Association of Chiefs of Police, Privacy Impact Assessment 
Report for the Utilization of License Plate Readers, at 13 
(Sept. 2009), https://www.theiacp.org/sites/default/files/all 
/k-m/LPR_Privacy_Impact_Assessment.pdf [https://perma.cc/M2T4 
-G5F5]. 
25 
 
1032, 1044 (2017) (ALPR data "could potentially reveal where [a] 
person lives, works, or frequently visits"). 
 
Similarly, with cameras in enough locations, the hot list 
feature could implicate constitutional search protections by 
invading a reasonable expectation of privacy in one's real-time 
location.  If deployed widely enough, ALPRs could tell police 
someone's precise, real-time location virtually any time the 
person decided to drive, thus making ALPRs the vehicular 
equivalent of a cellular telephone "ping."  See Almonor, 482 
Mass. at 55 (Lenk, J., concurring) ("When police act on real-
time information by arriving at a person's location, they signal 
to both the individual and his or her associates that the person 
is being watched. . . .  To know that the government can find 
you, anywhere, at any time is -- in a word -- 'creepy'").  Of 
course, no matter how widely ALPRs are deployed, the exigency 
exception to the warrant requirement would apply to this hot 
list feature.13 
                                                          
 
 
13 Order TRF-11 gives a nonexclusive list of reasons for 
which authorized users may manually place a license plate on a 
hot list, including "AMBER" alerts, missing child alerts, 
missing college student bulletins, and "be on the look out" 
alerts.  In these circumstances, the use of real-time alerts may 
be constitutionally permissible under the exigent circumstances 
exception to the warrant requirement.  See Riley v. California, 
573 U.S. 373, 388, 391, 402 (2014) (repeatedly noting how 
exigent circumstances exception might apply to warrant 
requirement for cellular telephone searches); Warden, Md. 
Penitentiary v. Hayden, 387 U.S. 294, 298–299 (1967) ("The 
Fourth Amendment does not require police officers to delay in 
26 
 
 
Finally, like carrying a cellular telephone, driving is an 
indispensable part of modern life, one we cannot and do not 
expect residents to forgo in order to avoid government 
surveillance. 
 
B.  Number and location of ALPR data collection points in 
this case.  On this record, however, we need not, and indeed 
cannot, determine how pervasive a system of ALPRs would have to 
be to invade a reasonable expectation of privacy.  While a 
testifying expert alluded to cameras "all over the [S]tate," the 
record is silent as to how many of these cameras currently 
exist,14 where they are located, and how many of them detected 
the defendant. 
 
Therefore, for this case, we consider the constitutional 
import of four cameras placed at two fixed locations on the ends 
of the Bourne and Sagamore bridges.  "Fourth Amendment [and art. 
14] cases must be decided on the facts of each case, not by 
extravagant generalizations.  '[W]e have never held that 
                                                          
 
the course of an investigation if to do so would gravely 
endanger their lives or the lives of others").  Similarly, the 
use of ALPRs to find a vehicle reported stolen would not be 
constitutionally impermissible, because the driver of a stolen 
vehicle does not have a reasonable expectation of privacy in the 
location of someone else's automobile. 
 
 
14 The amici submit that, in 2015, there were 168 ALPR 
cameras in operation in Massachusetts.  The information provided 
by the amici was not before the motion judge and remains 
untested by the adversarial process. 
27 
 
potential, as opposed to actual, invasions of privacy constitute 
searches for purposes of the Fourth Amendment.'"  Dow Chem. Co. 
v. United States, 476 U.S. 227, 238 n.5 (1986), quoting United 
States v. Karo, 468 U.S. 705, 712 (1984). 
 
"There is no real question that the government, without 
securing a warrant, may use electronic devices to monitor an 
individual's movements in public to the extent that the same 
result could be achieved through visual surveillance."  
Augustine, 467 Mass. at 252.  It is an entirely ordinary 
experience to drive past a police officer in a cruiser observing 
traffic on the side of the road, and, of course, an officer may 
read or write down a publicly displayed license plate number.  
See Starr, 55 Mass. App. Ct. at 594.  In this way, a single 
license plate reader is similar to traditional surveillance 
techniques.  On the other hand, four factors distinguish ALPRs 
from an officer parked on the side of the road:  (1) the policy 
of retaining the information for, at a minimum, one year; 
(2) the ability to record the license plate number of nearly 
every passing vehicle; (3) the continuous, twenty-four hour 
nature of the surveillance; and (4) the fact that the recorded 
license plate number is linked to the location of the 
observation.  These are enhancements of what reasonably might be 
expected from the police. 
28 
 
 
The limited number of cameras and their specific 
placements, however, also are relevant in determining whether 
they reveal a mosaic of location information that is 
sufficiently detailed to invade a reasonable expectation of 
privacy.  The cameras in question here gave police only the 
ability to determine whether the defendant was passing onto or 
off of the Cape at a particular moment, and when he had done so 
previously.  This limited surveillance does not allow the 
Commonwealth to monitor the whole of the defendant's public 
movements, or even his progress on a single journey.  These 
particular cameras make this case perhaps more analogous to 
CSLI, if there were only two cellular telephone towers 
collecting data.  Such a limited picture does not divulge "the 
whole of [the defendant's] physical movements," Carpenter, 138 
S. Ct. at 2217, or track enough of his comings and goings so as 
to reveal "the privacies of life."  Id., quoting Riley, 573 U.S. 
at 403.  See Boyd v. United States, 116 U.S. 616, 630 (1886). 
 
While we cannot say precisely how detailed a picture of the 
defendant's movements must be revealed to invoke constitutional 
protections, it is not that produced by four cameras at fixed 
locations on the ends of two bridges.15  Therefore, we conclude 
                                                          
 
 
15 In declining to establish a bright-line rule for when the 
use of ALPRs constitutes a search, we recognize this may bring 
some interim confusion.  We trust, however, that as our cases 
develop, this constitutional line gradually and appropriately 
29 
 
that the limited use of ALPRs in this case does not constitute a 
search within the meaning of either art. 14 or the Fourth 
Amendment.16 
 
b.  Defendant's other arguments.  We turn to the 
defendant's remaining claims.  He argues that various evidence 
should be suppressed because (1) the Barnstable police did not 
show a written policy governing ALPR use, and the State police 
ALPR policy, adopted by the Barnstable police, is deficient and 
constitutionally inadequate; (2) the use of ALPR systems 
violates 18 U.S.C. §§ 2701-2712, the Federal Stored 
Communications Act (SCA), and 18 U.S.C. §§ 2510-2523, the 
Federal Electronic Communications Privacy Act (ECPA); (3) the 
court should adopt the doctrine of target standing; and (4) the 
incriminating statements were involuntarily coerced through 
                                                          
 
will come into focus.  "The judiciary risks error by elaborating 
too fully on the Fourth Amendment [or art. 14] implications of 
emerging technology before its role in society has become 
clear."  Ontario v. Quon, 560 U.S. 746, 759 (2010). 
 
 
16 The defendant argues that, if the ALPR data were 
suppressed, there would have been no probable cause for his 
arrest.  Because we conclude that the use of the ALPR data was 
not a search in the constitutional sense, the data gleaned from 
the use of the ALPR properly is considered in the probable cause 
analysis.  We discern no error in the motion judge's 
determination that there was probable cause to arrest the 
defendant when the ALPR data is included in that analysis. 
30 
 
police trickery in violation of the defendant's Miranda rights.17  
We conclude that each of these arguments is without merit. 
 
i.  Role of police policies.  The defendant argues that, 
because the Barnstable police did not introduce a written policy 
governing police use of ALPR data, and because the State police 
policy, Order TRF-11, is inadequately specific, the evidence 
against him must be suppressed.  In support of this argument, 
the defendant relies on cases where we have required police to 
introduce evidence of a written policy to justify warrantless 
inventory searches or to demonstrate "that sobriety checkpoints 
be governed by standard, neutral guidelines that clearly forbid 
the arbitrary selection of vehicles to be initially stopped."  
Commonwealth v. Murphy, 454 Mass. 318, 323 (2009) (sobriety 
checkpoint guidelines).  See Commonwealth v. Bishop, 402 Mass. 
449, 451 (1988) ("art. 14 . . . requires the exclusion of 
evidence seized during an inventory search not conducted 
pursuant to standard police procedures, which procedures, from 
now on, must be in writing"). 
                                                          
 
 
17 In addition to the arguments discussed here, the 
defendant contends that the seizure of his bail money was 
unlawful.  The seizure of the defendant's bail money was not 
part of the judge's decision on the motion to suppress and 
therefore is not properly before this court.  See Mass. R. Crim. 
P. 15 (a) (2), as appearing in 474 Mass. 1501 (2016).  
Accordingly, we do not consider it. 
31 
 
 
This argument is unavailing.  These cases involve the 
reasonableness of a search or seizure conducted under specific 
exceptions to the warrant requirement, not the threshold 
constitutional question whether a search or seizure has occurred 
at all.  Detailed policy guidelines for police use of ALPRs well 
may be a "good idea," Riley, 573 U.S. at 398, but their 
existence or lack thereof does not determine the constitutional 
question. 
 
ii.  Statutory claims.  The defendant argues further that 
the government's use of ALPR data is subject to the SCA and the 
ECPA.  Neither statute, however, is applicable.18  The SCA 
prevents the government from compelling a "provider of 
electronic communication service" to produce such communications 
without following certain procedures.  See 18 U.S.C. § 2703.  
Here, the government did not compel production of electronic 
communications, but, rather, created and used them in the first 
instance.  Similarly, the ECPA regulates the interception of 
                                                          
 
 
18 The defendant's reliance on G. L. c. 214, § 1B, is 
similarly misplaced.  That statute creates a cause of action for 
tort liability to "protect[] individuals from 'disclosure of 
facts . . . that are of a highly personal or intimate nature 
when there exists no legitimate, countervailing interest.'"  Doe 
v. Brandeis Univ., 177 F. Supp. 3d 561, 616 (D. Mass. 2016), 
quoting Dasey v. Anderson, 304 F.3d 148, 153–154 (1st Cir. 
2002).  While it conceivably could support tort litigation 
against government actors (subject, of course, to sovereign 
immunity constraints), it has no application to the criminal 
suppression context. 
32 
 
wire, oral, and electronic communications.  See 18 U.S.C. 
§ 2511.  As the motion judge correctly determined, it would 
produce an absurd reading of the statute to conclude that 
officers were intercepting their own communications when 
receiving real-time alerts.  See 18 U.S.C. § 2511(2)(c) ("It 
shall not be unlawful under this chapter for a person acting 
under color of law to intercept a wire, oral, or electronic 
communication, where such person is a party to the communication 
. . .").  See also 18 U.S.C. § 2510(5)(a) (exempting any 
telephone or equipment used by law enforcement officers in 
course of their duties from types of devices that can be used to 
"intercept"). 
 
iii.  Target standing.  The defendant also argues that this 
court should adopt the doctrine of "target standing," which 
would give him standing to contest the search of his codefendant 
because he was one of that search's secondary targets.  See 
Commonwealth v. Santiago, 470 Mass. 574, 577 (2015).  It would 
allow him "to assert that a violation of the Fourth Amendment 
rights of a third party entitled him to have evidence suppressed 
at his trial."  Id.  The United States Supreme Court has 
rejected the doctrine with respect to the Fourth Amendment.  
Rakas v. Illinois, 439 U.S. 128, 132-133 (1978).  We also 
repeatedly have declined to adopt target standing under art. 14, 
but have left open the possibility of applying the doctrine in 
33 
 
cases of "distinctly egregious police conduct."  See Santiago, 
supra at 577-578.  Nothing in this record suggests "distinctly 
egregious police conduct."  Therefore, the defendant does not 
have target standing to challenge evidence seized from his 
codefendant. 
 
iv.  Miranda waiver.  The defendant argues that his waiver 
of his Miranda rights and the statements he made to police were 
involuntary because the officers repeatedly told him that he was 
not under arrest.  The tests to determine whether a Miranda 
waiver was voluntary and for the voluntariness of a statement 
are "essentially the same" (citation omitted).  Commonwealth v. 
Newson, 471 Mass. 222, 229 (2015). 
 
With respect to the Miranda issue, the motion judge found 
the following.  First, the defendant was under arrest at the 
time he was handcuffed during the roadside stop.  He properly 
and carefully was advised of his Miranda rights immediately 
after being handcuffed, and again at the police station.  He 
understood these rights both times. 
 
We agree with the motion judge that questions asked at the 
roadside and at the police station constituted custodial 
interrogation.  Considering the totality of the circumstances, 
the only factor indicating a lack of voluntariness was the 
officers' statements that the defendant was not under arrest and 
that he might avoid arrest by giving the information he 
34 
 
initially promised.  The defendant argues that the waiver and 
the statements were involuntary based on these deceptive 
representations. 
 
"[D]eception or trickery does not necessarily compel 
suppression of the confession or admission but, instead, is one 
factor to be considered in a totality of the circumstances 
analysis."  Newson, 471 Mass. at 230, quoting Commonwealth v. 
Tremblay, 460 Mass. 199, 208 (2011).  In Newson, supra, this 
court held that even if an officer engaged in deceit or trickery 
by telling a defendant that he was not under arrest, such deceit 
would not be enough to demonstrate involuntariness.  Here, the 
facts are essentially the same.  Therefore, we do not disturb 
the judge's finding that the Commonwealth proved beyond a 
reasonable doubt that the statements and the Miranda waiver were 
voluntary. 
 
3.  Conclusion.  While we recognize that the widespread use 
of ALPRs in the Commonwealth could implicate constitutional 
protections against unreasonable searches, the limited use of 
the technology in this case does not. 
Order denying motions to 
  suppress affirmed. 
 
 
 
 
GANTS, C.J. (concurring).  I agree with the court that, if 
the State police had obtained historical locational data 
regarding the defendant's vehicle from enough automatic license 
plate readers (ALRPs) in enough locations, the mosaic that such 
collection would create of the defendant's movements "would 
invade a reasonable expectation of privacy and would constitute 
a search for constitutional purposes."  Ante at    .  I also 
agree with the court that the locational information regarding 
the defendant that was obtained from four ALPRs at two fixed 
locations on two bridges falls short of creating the type of 
mosaic that would constitute a search within the meaning of 
either art. 14 of the Massachusetts Declaration of Rights or the 
Fourth Amendment to the United States Constitution.  And I agree 
that the court is correct to forbear from declaring in this case 
"precisely how detailed a picture of the defendant's movements 
must be revealed to invoke constitutional protections."  Id. 
at    .  I write separately not to attempt to answer how 
detailed the picture must be but to suggest an analytical 
framework that might prove useful in future cases. 
 
It is important to recognize that this is the first case we 
have encountered where the State police are collecting and 
storing a vast amount of locational data, from which they 
potentially might conduct a targeted search of locational 
information for a particular person or vehicle without probable 
2 
 
 
cause and without court authorization.  Cellular telephone 
companies possess even more locational data that can track the 
movements of a cellular telephone (and thus the person in 
possession of it), but law enforcement may obtain that 
information from these companies only through a search warrant 
or court order. 
 
Under our case law, a search warrant based on probable 
cause is required for law enforcement to obtain more than six 
hours of historical telephone call cellular site location 
information (CSLI) regarding a particular individual.  See 
Commonwealth v. Estabrook, 472 Mass. 852, 854 (2015); 
Commonwealth v. Augustine, 467 Mass. 230, 255 (2014), S.C., 470 
Mass. 837 (2015).  A court order under 18 U.S.C. § 2703 based on 
"specific and articulable facts" that show "reasonable grounds 
to believe" that the records "are relevant and material to an 
ongoing criminal investigation" suffices under art. 14 to obtain 
six hours or less of CSLI regarding a particular individual.  
See Estabrook, supra at 855 n.4, 858.  If a law enforcement 
agency possessed comparable historical locational data that 
could produce a mosaic of an individual's movements equivalent 
to that produced by CSLI, whether because it purchased bulk CSLI 
data from a vendor or because it had a vast array of ALPRs or 
surveillance cameras using facial recognition software, we would 
require law enforcement to obtain a search warrant based on 
3 
 
 
probable cause before it could retrieve the locational data for 
that mosaic regarding a targeted individual. 
 
But what if the historical locational information regarding 
a targeted individual that can be obtained from data in the 
possession of a law enforcement agency could yield a mosaic of 
location points that is less than that created by CSLI but 
greater than the four location points established in this 
record?  Pragmatically, I submit we have two alternatives.  Our 
first option is to determine based on the facts of a particular 
case when the locational mosaic of a targeted individual's 
movements crosses the threshold of the reasonable expectation of 
privacy.  A mosaic above that threshold would require a search 
warrant based on probable cause, but a mosaic below that 
threshold would not require any court authorization. 
 
Alternatively, we could strike a balance analogous to that 
struck by the United States Supreme Court in Terry v. Ohio, 392 
U.S. 1, 21 (1968), and decide that there are two locational 
mosaic thresholds:  a lesser threshold that may be permissibly 
crossed with a court order supported by an affidavit showing 
reasonable suspicion and a greater threshold that is permissibly 
crossed only with a search warrant supported by probable cause. 
The reasonable suspicion standard would require "specific and 
articulable facts" demonstrating reasonable suspicion that the 
targeted individual has committed, is committing, or will commit 
4 
 
 
a crime, see id. at 21-22, and that there are reasonable grounds 
to believe that the data obtained from the query are relevant 
and material to an investigation of the crime.  The reasonable 
suspicion standard is different from and more exacting than the 
standard required under 18 U.S.C. § 2703 to obtain six hours or 
less of CSLI, which requires only "specific and articulable 
facts" that show "reasonable grounds to believe" that the 
records "are relevant and material to an ongoing criminal 
investigation." 
 
This second alternative would mean that law enforcement 
agencies would need to obtain court authorization more often 
before retrieving targeted individual historical locational 
information in their possession because queries that would not 
require a showing of probable cause might still require a 
showing of reasonable suspicion.  But the benefit to law 
enforcement would be that, if the police sought a court order 
based on reasonable suspicion and a reviewing court determined 
that the query sought locational data that could yield a mosaic 
of movement requiring a showing of probable cause, the search 
would not be found unconstitutional (and the information 
collected would not be suppressed) if the reviewing court found 
that the affidavit supported a finding of probable cause.  In 
contrast, where no court order was obtained and a reviewing 
court determined that probable cause or reasonable suspicion was 
5 
 
 
required to support the retrieval of historical locational 
information, the data retrieved from the query would have to be 
suppressed even if law enforcement could have met the applicable 
standard. 
 
Regardless of which alternative the court ultimately 
chooses, a reviewing court will need to know the extent of the 
mosaic that was possible from the retrieval of historical 
locational information regarding the movements of a targeted 
individual, because only then can the court accurately determine 
whether the threshold had been crossed.  Therefore, unless the 
law enforcement agency has sought prior court approval to search 
for particularized locational data in its possession, the agency 
will have to preserve each and every search query for the 
retrieval of historical locational information regarding a 
targeted individual.  For instance, if the State police maintain 
1,000 ALPRs at different locations throughout the Commonwealth, 
it matters whether they searched for a suspect's vehicle from 
the data yielded by all 1,000 cameras or only by four cameras, 
and it matters whether they gathered this data for one day or 
one hundred days.  And regardless of whether a court authorized 
the search, the agency must preserve the historical locational 
data regarding a particular individual that the agency retrieved 
as a result of such queries from the data in its possession, 
even when that exceeds the amount of data that the agency uses 
6 
 
 
in an investigation or at trial.  Cf. Estabrook, 472 Mass. at 
859 ("the salient consideration is the length of time for which 
a person's CSLI is requested, not the time covered by the 
person's CSLI that the Commonwealth ultimately seeks to use as 
evidence at trial").  And the agency must make this preserved 
data and search request available in discovery when sought by 
the defendant.  Only then will a court have the information it 
needs to determine whether the retrieval of locational 
information regarding a targeted individual crossed a 
constitutional threshold that requires court authorization and 
either reasonable suspicion or probable cause.