Title: Commonwealth v. Arrington
Citation: N/A
Docket Number: SJC-13499
State: Massachusetts
Issuer: Massachusetts Supreme Court
Date: February 20, 2024

NOTICE:  All slip opinions and orders are subject to formal 
revision and are superseded by the advance sheets and bound 
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error or other formal error, please notify the Reporter of 
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SJC-13499 
 
COMMONWEALTH  vs.  VICTOR ARRINGTON. 
 
 
 
Suffolk.     December 6, 2023. - February 20, 2024. 
 
Present:  Budd, C.J., Gaziano, Lowy, Kafker, Wendlandt, 
& Georges, JJ.1 
 
 
Cellular Telephone.  Practice, Criminal, Motion in limine, 
Interlocutory appeal, Appeal by Commonwealth, Presumptions 
and burden of proof.  Evidence, Expert opinion, Scientific 
test, Presumptions and burden of proof.  Witness, Expert.  
Rules of Criminal Procedure. 
 
 
 
 
Civil action commenced in the Supreme Judicial Court for 
the county of Suffolk on September 13, 2023. 
 
 
The case was reported by Kafker, J. 
 
 
Ian MacLean, Assistant District Attorney (Edmond J. Zabin, 
Assistant District Attorney, also present) for the Commonwealth. 
Michelle Menken (E. Peter Parker also present) for the 
respondent. 
The following submitted briefs for amici curiae: 
Jessica Hyde & Eoghan Casey, pro se. 
Patrick Levin, Committee for Public Counsel Services, for 
Committee for Public Counsel Services. 
Dan Loper, Karl Epps, & Steven Verronneau, pro se. 
 
1 Justice Lowy participated in the deliberation on this case 
and authored his concurrence prior to his retirement. 
 
2 
 
Jennifer Stisa Granick & Andrew Crocker, of California, 
Michael W. Price & Hannah Zhao, of New York, Jessica J. Lewis, 
Jessie J. Rossman, Daniel K. Gelb, Nathan Freed Wessler, & 
Chauncey B. Wood for American Civil Liberties Union & others. 
 
 
KAFKER, J.  The Commonwealth alleges that in March of 2015, 
the defendant, Victor Arrington, and two others broke into a 
home, killed one resident, grievously wounded another, and 
attempted to set fire to the home.2  Prosecuting the defendant 
for murder in the first degree and other crimes related to the 
home invasion,3 the Commonwealth moved in limine to permit the 
introduction at trial of frequent location history (FLH) data 
retrieved from the defendant's cell phone, an Apple iPhone 6.4  
The Commonwealth contends that expert testimony regarding the 
FLH data would establish that the defendant's cell phone was in 
the immediate vicinity of the crime scene at the time the crime 
was committed.  Because FLH data has never been admitted as 
 
2 Although this case comes to us on a reservation and report 
by a single justice of the Commonwealth's petition pursuant to 
G. L. c. 211, § 3, for convenience, we refer to Victor Arrington 
as the "defendant," rather than the "respondent." 
 
3 The defendant was also charged with home invasion, two 
counts of kidnapping, arson of a dwelling house, armed assault 
with intent to murder, and possession of a firearm without a 
license. 
 
4 FLH data are generated from location data points saved on 
an iPhone using a proprietary algorithm to identify locations 
that a user has visited several times.  See part 1.b, infra.  
The Commonwealth contends that FLH data reliably provide an 
approximate location for the cell phone for a particular time.    
3 
 
evidence in any court in the Commonwealth, or apparently in any 
other jurisdiction in the country, the trial judge held a three-
day evidentiary hearing to determine whether the Commonwealth's 
proffered expert testimony on FLH data would be permitted.  The 
trial judge denied the Commonwealth's motion, and the 
Commonwealth sought appellate review.   
As a preliminary issue, the parties disagree as to whether 
the Commonwealth may appeal from the denial of its motion to 
admit expert testimony under Mass. R. Crim. P. 15 (a) (2), as 
appearing in 474 Mass. 1501 (2016) (rule 15 [a] [2]), or whether 
its sole avenue for interlocutory review is a petition under 
G. L. c. 211, § 3.  On the merits, the Commonwealth contends 
that the trial judge abused his discretion in denying its motion 
on Daubert-Lanigan grounds.  See Daubert v. Merrell Dow Pharms., 
Inc., 509 U.S. 579, 585-595 (1993); Commonwealth v. Lanigan, 419 
Mass. 15, 25-26 (1994).  Both issues were presented to a single 
justice of this court, who reserved and reported the case to the 
full court. 
As to the procedural question, rule 15 (a) (2) does not 
give the Commonwealth the ability to apply for leave to appeal 
from the denial of a motion in limine where, as here, the 
ruling, if allowed to stand, does not, "as a practical matter, 
. . . terminate the prosecution."  Commonwealth v. Anderson, 401 
Mass. 133, 135 (1987).  Instead, in such situations, the 
4 
 
appropriate avenue for the Commonwealth to seek interlocutory 
review of a ruling on a motion in limine is through a petition 
under G. L. c. 211, § 3.  Turning to the merits of the 
Commonwealth's petition here, we discern no abuse of discretion 
by the trial judge in denying the Commonwealth's motion to admit 
the proffered expert testimony on FLH data.  Accordingly, we 
affirm.5 
1.  Background.  a.  Facts.  As trial has yet to begin, we 
summarize the evidence the Commonwealth has stated it expects to 
introduce at trial.  See Commonwealth v. Spencer, 465 Mass. 32, 
33 (2013).  We reserve certain facts for our discussion of the 
merits of the Commonwealth's motion to admit FLH evidence.   
The Commonwealth alleges that at around 10:51 A.M. on March 
31, 2015, the defendant, a cooperating witness, and Jeromie 
Johnson6 participated in a home invasion on Harvard Street in the 
Dorchester section of Boston.  Richard Long, Yvette O'Brien, and 
O'Brien's newborn son were at home at the time of the attack.  
 
5 We acknowledge the amicus briefs submitted by the American 
Civil Liberties Union, the American Civil Liberties Union of 
Massachusetts, Inc., the Massachusetts Association of Criminal 
Defense Lawyers, the National Association of Criminal Defense 
Lawyers, Inc., and the Electronic Frontier Foundation; the 
Committee for Public Council Services; Jessica Hyde and Eoghan 
Casey; and Dan Loper, Karl Epps, and Steven Verronneau. 
 
6 Johnson was killed about a week after the home invasion at 
issue here, and thus is not a codefendant in this case. 
  
5 
 
Johnson and the defendant bound Long and O'Brien with electrical 
cords, cut Long with a knife, and shot both Long and O'Brien in 
the head.  They then set fire to the house.  Long died from his 
wounds.  O'Brien survived the gunshot wound and can describe the 
events that occurred in the apartment until she was shot in the 
head, but she is unable to identify the perpetrators.  The 
cooperating witness agreed to testify against the defendant in 
exchange for facing reduced charges.  The Commonwealth asserts 
that the cooperating witness will identify the perpetrators and 
their roles in the home invasion and associated crimes. 
The defendant allegedly drove to the crime scene in a white 
sedan rented by his girlfriend for his use.  The defendant's car 
was captured on video being driven down Blue Hill Avenue in 
Dorchester, with another car carrying Johnson and the 
cooperating witness following behind.  The defendant's car was 
next seen parked on Paxton Street near the scene of the crime.  
At 10:44 A.M., the defendant received a call from Johnson 
lasting over three minutes, and the defendant called Johnson 
several times over the next few minutes with no answer.  The 
defendant's telephone utilized a cell tower the coverage area of 
which included the crime scene for these calls.7  A video camera 
at a Department of Youth Services facility located across the 
 
7 The defendant's cell phone was seized on April 8, 2015.  
 
6 
 
street from the crime scene captured grainy video footage of two 
people approaching the victims' home at 10:51 A.M., and the same 
video camera captured footage of three people leaving at 11:20 
A.M.  The defendant's car was captured on video at 11:22 A.M. 
being driven down Blue Hill Avenue. 
b.  Frequent location history data.  When turned on, an 
iPhone generates location data points from sources such as 
global positioning system (GPS) data, nearby wireless computer 
network (Wi-Fi) access points, short-range wireless Bluetooth 
connections, and cell site location information (CSLI).  These 
location data points are stored on the iPhone's "Encrypted B" 
cache8 for between twenty-four and forty-eight hours.  In 2015, 
an algorithm on the iPhone would use these data points to create 
FLH data.9  The FLH data created by the algorithm consist of a 
 
8 A cache is "a computer memory with very short access time 
used for storage of frequently or recently used instructions or 
data."  Merriam-Webster Online Dictionary, https://www.merriam-
webster.com/dictionary/cache [https://perma.cc/FFL2-EEP7]. 
 
9 This information is referred to as "Significant Locations" 
on newer iPhone operating systems.  Documents provided to 
customers by Apple explain that "Significant Locations allows 
iPhone, iPad, Apple Watch, and iCloud to learn the places that 
are significant to a user in order to provide useful location-
related features and information in a way that Apple can't read.  
Data collected about a significant location includes the address 
the user travelled to, when they traveled there, how long they 
stayed, the amount of time spent commuting to the location, the 
method used to reach the location . . . , and the total number 
of times the user has visited that place."  
 
7 
 
longitude and latitude coordinate point and a circle around it, 
representing an amalgamation of the location data points.  The 
radius of the circle, labeled the "uncertainty" in the FLH data, 
represents the approximate area in which the cell phone was 
located.  The uncertainty radius can change from visit to visit 
to a frequent location, as can the coordinate point representing 
the center of the frequent location.  FLH data also provides an 
estimated time that the iPhone entered the location, and an 
estimated time the iPhone left the location.  The algorithm used 
to convert location data points into FLH data is proprietary, 
and thus the Commonwealth's expert did not have access to the 
algorithm itself during his testing of FLH data reliability.  
Moreover, it is unclear how the algorithm processes, or weighs, 
the different location data points generated by the iPhone. 
In 2022, a full-file system extraction was performed on the 
defendant's cell phone.  This extraction allowed the 
Commonwealth to access encrypted files on the cell phone, 
including its FLH data.10  The FLH data on the cell phone listed 
345 frequent location visits.  Of particular interest to the 
Commonwealth is frequent location no. 58.  Frequent location no. 
58 is centered on coordinates corresponding to a Harvard Street 
 
10 Although the FLH data for the date of the murder was 
available on the defendant's cell phone, the underlying location 
data that was used to produce the FLH data was no longer 
available. 
8 
 
address near the victims' home.  The uncertainty radius of 
frequent location no. 58 is forty-three meters, or 143 feet, 
which encompasses the crime scene.  The Commonwealth's proffered 
expert on FLH data, a senior crime analyst in the office of the 
district attorney for the Suffolk district (analyst), testified 
that he interpreted the FLH data retrieved from the defendant's 
cell phone to show that the phone entered the area represented 
in frequent location no. 58 at 10:36 A.M. on March 31, 2015, and 
left the area at 11:22 A.M that day.  The Commonwealth therefore 
contends that the proffered expert testimony on FLH data, if 
admitted, would corroborate the cooperating witness's testimony 
placing the defendant at the scene of the home invasion. 
c.  Procedural background.  In April 2023, the Commonwealth 
informed the judge that a Daubert-Lanigan hearing would be 
needed to determine the admissibility of FLH data evidence 
gathered from the defendant's cell phone.  In May, a Daubert-
Lanigan hearing was scheduled for July 27.  On July 26, the 
Commonwealth requested a continuance, and the hearing was 
continued to August 29.  Between June 16 and August 24, the 
analyst performed experiments on a test iPhone to determine the 
reliability of FLH data, with the majority of his experiments 
performed between August 14 and 24.  The Daubert-Lanigan hearing 
on the admissibility of FLH evidence was held on August 29, 
September 7, and September 8, ending four days before the 
9 
 
defendant's trial was scheduled to start on September 12.  The 
analyst was the only witness who testified at the hearing.   
At the evidentiary hearing, the analyst testified regarding 
his understanding of how FLH data are created.  Although the 
analyst did not have access to the algorithm that generates FLH 
data and could not testify as to how the algorithm converted 
location data inputs into FLH data, he explained the tests he 
had done to ascertain the reliability of FLH data in identifying 
where a cell phone is located at a particular time.  The analyst 
conducted tests of FLH data reliability using a "jailbroken"11 
iPhone (test iPhone) that was similar, but not identical, to the 
iPhone associated with the defendant.12  When pressed, the 
analyst acknowledged that there were likely differences in the 
FLH algorithms used by the two iPhones, and although he believed 
that any changes were not significant, he could not say for 
 
11 Jailbreaking is removing the built-in limitations from an 
electronic device, such as a cell phone.  Merriam-Webster Online 
Dictionary, https://www.merriam-webster.com/dictionary/jailbreak 
[https://perma.cc/7MR6-2LJ5].  The analyst jailbroke the iPhone 
he used to test FLH data in order to access location data that 
users normally cannot view. 
 
12 The defendant's cell phone is an iPhone 6 running the iOS 
8.1 operating system.  The analyst used an iPhone 5C running the 
iOS 8.4.1 operating system.  The analyst performed the testing 
using a different operating system from that found on the 
defendant's cell phone because the code used to jailbreak iOS 
8.4.1 is publicly available, whereas code to jailbreak iOS 8.1 
is not.  It is not clear why the analyst did not use an iPhone 6 
in his experiments.   
10 
 
sure.  The analyst conducted a total of twelve experiments using 
the test iPhone at five different locations in Boston.  
The Commonwealth also provided evidence regarding five 
locations that were identified as frequent locations on the 
defendant's cell phone.  The analyst discussed additional data 
retrieved from the defendant's cell phone that provided 
corroborating evidence that the defendant's phone was near 
locations corresponding with the frequent locations at the times 
indicated by the FLH data.  The analyst's proposed expert 
testimony would state, based on his interpretation of the FLH 
data recovered from the defendant's cell phone, that between 
10:36 A.M. and 11:22 A.M. on March 31, 2015, the defendant's 
phone was within a 143-foot radius of a Harvard Street address 
near the victims' home, an area that includes the scene of the 
crime.   
On September 11, 2023, the trial judge denied the 
Commonwealth's motion to permit the introduction of FLH evidence 
at trial.  On the same day, the Commonwealth filed a notice of 
appeal, believing that the notice of appeal would stay the trial 
court proceedings pursuant to Mass. R. Crim. P. 15 (e), as 
appearing in 474 Mass. 1501 (2016).  The defendant filed a 
response, arguing that the Commonwealth's notice of appeal did 
not automatically stay the trial court proceedings.  
Specifically, the defendant argued that the appeal procedures in 
11 
 
rule 15 were inapplicable, and that the Commonwealth's only 
avenue for interlocutory review of the denial of a motion in 
limine was a petition under G. L. c. 211, § 3, which, in turn, 
did not automatically stay the trial court proceedings.  The 
trial judge concluded that the Commonwealth's appeal was outside 
the scope of rule 15, but nonetheless stayed the proceedings to 
allow the Commonwealth to pursue relief through a G. L. c. 211, 
§ 3, petition.  A single justice of this court then extended the 
stay and subsequently reserved and reported the case to the full 
court, including both the procedural question whether this 
appeal was within the scope of rule 15 and the merits of whether 
the trial judge abused his discretion in denying the 
Commonwealth's motion to permit introduction of FLH data.  
2.  Discussion.  a.  Availability of appeal under rule 
15 (a) (2).  As a preliminary matter, we must determine whether 
the Commonwealth was entitled to appeal from the trial judge's 
ruling under rule 15 (a) (2), or whether its procedural avenue 
for relief must instead come from this court's superintendence 
powers under G. L. c. 211, § 3.  The Commonwealth contends that 
because the trial judge's ruling rejecting admission of expert 
testimony regarding FLH data had the effect of preventing the 
admission of "critical" evidence in its case against the 
defendant, the ruling is the functional equivalent of a motion 
12 
 
to suppress and thus entitles the Commonwealth to an appeal 
under rule 15 (a) (2).  We disagree.    
 
We construe our rules of procedure according to the 
ordinary canons of construction, beginning with the plain 
meaning of the text.  Commonwealth v. Wright, 479 Mass. 124, 133 
(2018).  The text of rule 15 (a) (2) provides for interlocutory 
appeal from "an order determining a motion to suppress evidence 
prior to trial."  By its express terms, rule 15 (a) (2) "does 
not encompass other interlocutory rulings, in part for sound 
reasons of judicial economy, as such 'ruling[s] [are] subject to 
change when the case unfolds.'"  See Spencer, 465 Mass. at 40 
n.11, quoting Luce v. United States, 469 U.S. 38, 41 (1984)).   
Although the text of rule 15 (a) (2) is directed only at 
motions to suppress, we have allowed a narrow exception to this 
general rule:  "if a motion to exclude all or most of the 
Commonwealth's incriminating evidence is allowed, and if, as a 
practical matter, that ruling (if permitted to stand) would 
terminate the prosecution, the Commonwealth may seek leave to 
appeal pursuant to [rule 15 (a) (2)]."  Anderson, 401 Mass. at 
135.  This narrow exception to, or more precisely, expansion of, 
rule 15 (a) (2) (Anderson expansion) recognizes that, in the 
very limited subset of cases where a ruling on a motion in 
limine to exclude evidence prevents the introduction of all or 
most of the Commonwealth's evidence, preventing the opportunity 
13 
 
for an interlocutory appeal could effectively preclude the 
Commonwealth from continuing the prosecution of serious crimes 
without any opportunity for appellate review.  See Commonwealth 
v. Ruiz, 480 Mass. 683, 692 (2018) ("important jurisprudential 
interests" are served by "the review of pretrial decisions that 
terminate criminal proceedings prior to a trial being held"). 
We have allowed this narrow expansion of the scope of rule 
15 (a) (2) because we have concluded that rule 15 (a) (2) should 
be read in the context of rule 15 as a whole, which allows 
interlocutory appeals from orders that would otherwise terminate 
a criminal proceeding.  See Mass. R. Crim. P. 15 (a) (1), as 
appearing in 474 Mass. 1501 (2016) (allowing Commonwealth to 
appeal following grant of motion to dismiss complaint or 
indictment, or from "a motion for appropriate relief" made 
pursuant to Mass. R. Crim. P. 13 [c], as appearing in 474 Mass. 
1501 [2016]); Mass. R. Crim. P. 15 (a) (3), as appearing in 476 
Mass. 1501 (2017) (Commonwealth may appeal from "a decision by a 
judge discharging a person pursuant to G. L. c. 119, § 72A").  
See also Ruiz, 480 Mass. at 692-693, quoting Burke v. 
Commonwealth, 373 Mass. 157, 160 (1977) (appeal from trial 
court's dismissal of indictment pursuant to rule 15 [a] [1] 
"allow[s] the Commonwealth to reinstitute proceedings terminated 
because of an incorrect ruling in the trial court, . . . but, on 
the other hand, . . . allow[s] [appellate courts] to affirm 
14 
 
preliminary rulings which, in effect, put an end to a particular 
prosecution"); Commonwealth v. Yelle, 390 Mass. 678, 685 (1984) 
(declining to consider pretrial motion to admit evidence as 
"motion for appropriate relief" under rule 15 [a] [1] in part 
because "[t]he allowance of a defendant's motion to admit 
evidence does not, as the allowance of a motion to suppress so 
often does in practical effect, terminate the proceedings").  
Barring appeals in such situations could "leave a class of 
cases, many of which involve serious crimes, lost either to 
further prosecution or any appellate review."  Ruiz, supra at 
693, quoting Burke, supra.  Indeed, rule 15 was adopted to 
implement G. L. c. 278, § 28E, a statute intended to allow the 
Commonwealth to appeal from rulings that would terminate 
criminal proceedings.  See Yelle, supra, citing Burke, supra at 
161 ("The Commonwealth's right to appeal from certain pretrial 
rulings under G. L. c. 278, § 28E, is based on the fact that 
those rulings preclude a public trial and entirely terminate the 
proceedings").   
The Commonwealth suggests that rule 15 (a) (2) should be 
interpreted more broadly to encompass other situations where 
"critical" evidence is excluded, even where the evidence 
excluded does not have the practical effect of terminating the 
criminal proceeding.  The Commonwealth thus proposes that, 
although the exclusion of its expert's testimony does not 
15 
 
prevent it from introducing all or most of its incriminating 
evidence at trial, the instant appeal is properly brought under 
rule 15 (a) (2) because the expert's testimony regarding FLH 
data is "critical" to the case against the defendant.   
Because its case at trial will rely significantly on 
testimony by a cooperating witness procured in exchange for a 
reduced sentence, we agree with the Commonwealth that evidence 
corroborating the cooperating witness's testimony (and, thus, 
bolstering the credibility of that testimony) might fairly be 
described as "critical" to the prosecution's case.  Nonetheless, 
we decline the Commonwealth's invitation to expand the scope of 
rule 15 (a) (2) to include the ruling on the motion in limine in 
the instant case.  The plain text of rule 15 (a) (2) refers only 
to motions to suppress and thus sets out the general rule.  As 
discussed supra, however, the purpose of rule 15 is to provide 
an avenue for interlocutory review of rulings that would 
otherwise terminate a criminal proceeding.  Thus, the narrow 
Anderson expansion that we have allowed is consonant with this 
purpose because it expands rule 15 (a) (2) only to include 
motions in limine that exclude so much incriminating evidence 
that the motion effectively forecloses the Commonwealth's 
ability to prosecute its case at trial.  See Anderson, 401 Mass. 
at 135.   
16 
 
We have also previously observed that further expanding the 
availability of interlocutory appeals pursuant to rule 15 would 
create the potential for delay and disruption in criminal 
proceedings.  See Ruiz, 480 Mass. at 694 ("an unrestrained right 
to pretrial appeals by the Commonwealth may be burdensome on 
defendants [and the courts]"); Yelle, 390 Mass. at 687 (to allow 
Commonwealth right to interlocutory review from every adverse 
evidentiary ruling "would be to create a potential for 
disruption of every criminal trial where a disgruntled 
prosecutor could cause the stay of the proceeding, pending 
appellate review of evidentiary rulings").  See also 
Commonwealth v. Cavanaugh, 366 Mass. 277, 279 (1974) 
("interlocutory appeals and reports should not be permitted to 
become additional causes of the delays in criminal trials which 
are already too prevalent").13 
 
13 Under Mass. R. Crim. P. 15 (e), criminal proceedings are 
automatically stayed for thirty days following a ruling subject 
to rule 15's interlocutory procedures.  If, as the Commonwealth 
urges, rule 15 (a) (2) were expanded to allow appeals from 
rulings on motions in limine that exclude "critical" evidence, 
rulings on such motions would automatically stay proceedings to 
give the Commonwealth time to consider whether to appeal, which 
would invariably lead to delays in criminal proceedings.  See 
Yelle, 390 Mass. at 687.  Moreover, as in this case, there would 
likely be further delay occasioned by disagreements between the 
parties as to whether excluded evidence was "critical."  We note 
that in the present case, the trial judge decided the motion in 
limine on the admissibility of the Commonwealth's proffered 
expert testimony the day before the scheduled start of trial.  
The interlocutory appellate proceedings in this matter have thus 
occasioned significant delay to the anticipated start of trial. 
17 
 
The Commonwealth contends nonetheless that in our case law 
following Anderson, we have expanded the circumstances in which 
the Commonwealth may use rule 15 (a) (2) to appeal from motions 
in limine beyond those that effectively foreclose the 
Commonwealth's ability to prosecute its case at trial.  The 
Commonwealth's contention relies in part on this court's 
decision in Spencer, 465 Mass. 32, which it suggests stands for 
the proposition that the exclusion of "critical" evidence is 
sufficient to allow the Commonwealth to request leave to appeal 
under rule 15 (a) (2). 
In Spencer, 465 Mass. at 40, the Commonwealth filed an 
emergency petition for extraordinary relief pursuant to G. L. 
c. 211, § 3, arguing that motions in limine "sought to exclude 
most of the Commonwealth's incriminating evidence."  The 
Commonwealth represented that the evidence excluded by the 
judge's preliminary rulings was "critical to establish[ing] 
identity, motive, and consciousness of guilt."  Id. at 44.  
After presenting its arguments before a single justice, "the 
single justice granted the petition for extraordinary relief, 
ordered that proceedings in the Superior Court be stayed, and 
ordered the Commonwealth to file an interlocutory appeal" under 
rule 15 (a) (2).  Id. at 40.  "The single justice then allowed 
the appeal to proceed before this court."  Id. at 41.   
18 
 
In Spencer, the parties did not challenge the single 
justice's order to file an appeal under rule 15 (a) (2), so we 
did not address whether it was appropriate for the Commonwealth 
to proceed under rule 15.14  See id. at 40-41.  However, in 
discerning no error in the trial judge's rulings, we did 
observe, after a more thorough examination of the record, that 
"[e]ven had the judge allowed the defendant's motion to exclude 
the recordings in their entirety, the Commonwealth would still 
have ample evidence upon which to proceed to trial."  Id. at 45.  
Indeed, we expressly stated:  "Were the judge's preliminary 
rulings . . . permitted to stand, it would not as a practical 
matter [have] 'terminate[d] the prosecution.'"  Id., quoting 
Anderson, 401 Mass. at 133.  We therefore do not understand 
Spencer to be an endorsement of the proposition that the 
exclusion of "critical" evidence before a trial is sufficient 
for the Commonwealth to avail itself of an interlocutory appeal 
under rule 15 (a) (2).  Compare Spencer, supra at 43 (assertion 
 
14 Similarly, in Commonwealth v. Beausoleil, 397 Mass. 206, 
207-208 (1986), a single justice of this court chose to treat a 
petition under G. L. c. 211, § 3, challenging the exclusion of 
evidence, as an appeal from a motion to suppress under rule 
15 (a) (2).  On appeal before this court, the parties did not 
challenge the single justice's decision, so we did not address 
the issue.  See id. at 208 n.2.  To the extent our decision in 
Beausoleil has been read to support a further expansion of rule 
15 beyond the narrow Anderson expansion, such a reading is 
incorrect. The correctness of the single justice's consideration 
of the exclusion of evidence as a rule 15 motion was not raised 
and not decided.  
19 
 
"that the excluded recordings comprise[d] 'most of the 
Commonwealth's evidence' . . . [did] not withstand close 
scrutiny of the record"), with Anderson, supra at 135 ("if a 
motion to exclude all or most of the Commonwealth's 
incriminating evidence is allowed, and if, as a practical 
matter, that ruling [if permitted to stand] would terminate the 
prosecution, the Commonwealth may seek leave to appeal pursuant 
to [rule 15 (a) (2)]").  Rather, in Spencer, supra at 43-44, we 
implicitly disapproved of the Commonwealth having the 
opportunity for an interlocutory appeal under rule 15 (a) (2) 
where excluded evidence did not effectively terminate the 
prosecution.  We therefore clarify here that any reading of 
Spencer suggesting that the exclusion of "critical" evidence 
alone is sufficient to allow the Commonwealth to apply for leave 
to appeal under rule 15 (a) (2) is incorrect.  See Anderson, 
supra; Mass. R. Crim. P. 15 (a) (2).15 
 
15 Our discussion of rule 15 (a) (2) in Commonwealth v. 
Fontanez, 482 Mass. 22 (2019), and the cases cited therein, 
similarly does not support the Commonwealth's reading of rule 
15.  See id. at 23 n.1, 26 (Commonwealth could have filed for 
leave to appeal under rule 15 [a] [2] where "the judge's 
decision to exclude the now deceased victim's testimony 
effectively foreclose[d] the Commonwealth's ability to prosecute 
a serious crime").  See also Commonwealth v. Arrington, 455 
Mass. 437, 437-438 (2009) (Commonwealth appealed under rule 
15 [a] [2] from order excluding prior recorded testimony of 
deceased victim, only eyewitness to crime); Commonwealth v. 
Gonsalves, 445 Mass. 1, 15 (2005), cert. denied, 548 U.S. 926 
(2006), abrogated on other grounds as recognized by Commonwealth 
v. Rand, 487 Mass. 811, 825 n.14 (2021) (judge's order excluding 
20 
 
 
In the present case, it is undisputed that the FLH data 
evidence does not constitute "all or most of the Commonwealth's 
incriminating evidence."  See Anderson, 401 Mass. at 135.  
Indeed, the Commonwealth plans to have eyewitness testimony from 
its cooperating witness placing the defendant at the scene of 
the crime and describing his role in the murder and other 
crimes.  The Commonwealth also intends to introduce video 
recordings showing that a vehicle matching the description of 
the vehicle rented for the defendant was in the area of the 
victims' home prior to the crime and left the area after three 
figures were recorded leaving the crime scene.  Furthermore, 
CSLI data will show that the defendant's cell phone was in the 
area of the victim's home during the relevant time frame as 
well.  Because this case does not involve the determination of a 
motion to suppress, and because the exclusion of the FLH data 
will not, as a practical matter, terminate the Commonwealth's 
prosecution, the instant appeal is outside the scope of rule 
15 (a) (2) and the narrow expansion of the scope of rule 
15 (a) (2) beyond motions to suppress established in Anderson.  
See id.  We therefore hold that the proper route for this appeal 
was a petition for extraordinary relief under G. L. c. 211, § 3. 
 
testimony by victim to police officers where victim was only 
eyewitness to crime "effectively prevent[ed] the Commonwealth's 
case against the defendant from proceeding").  
21 
 
 
Because this case was reserved and reported by the single 
justice, we need not decide whether the case meets the standard 
for relief under G. L. c. 211, § 3.  See Commonwealth v. 
Whitfield, 492 Mass. 61, 67 n.9 (2023) ("Where the single 
justice has exercised . . . discretion to reserve and report the 
matter, we proceed to adjudicate the merits").  See also 
Commonwealth v. Lucas, 472 Mass. 387, 390 (2015), quoting Burke, 
373 Mass. at 159 ("where, as here, a single justice of this 
court reserves and reports an interlocutory matter to this 
court, we grant the litigant full appellate review").  However, 
we reemphasize that G. L. c. 211, § 3, "is not a means for 
second guessing a trial judge's evidentiary rulings."  Anderson, 
401 Mass. at 134, quoting Yelle, 390 Mass. at 687.  Thus, even 
if the Commonwealth has no other means to seek review of a trial 
court's ruling on a motion in limine, that does not render 
review under G. L. c. 211, § 3, automatic.  See Commonwealth v. 
Fontanez, 482 Mass. 22, 25 (2019); Yelle, supra at 685-686.  
Rather, to obtain review of such rulings pursuant to G. L. 
c. 211, § 3, the Commonwealth "must still demonstrate to the 
single justice that its petition presents the type of 
exceptional matter that requires the court's extraordinary 
intervention."  Fontanez, supra.   
b.  Admissibility of FLH data.  Turning to the merits of 
the Commonwealth's appeal, we consider whether the trial judge 
22 
 
abused his discretion in denying the Commonwealth's motion to 
permit expert testimony on FLH data.  See Commonwealth v. Davis, 
487 Mass. 448, 455 (2021), S.C., 491 Mass. 1011 (2023).  We 
conclude that he did not and therefore affirm. 
Admission of scientific or technological evidence is 
governed by what has come to be known as the Daubert-Lanigan 
standard.16  See Daubert, 509 U.S. at 585-595; Lanigan, 419 Mass. 
at 25-26.  Under the Daubert-Lanigan standard, "[t]he judge, 
acting as gatekeeper, is responsible for 'mak[ing] a preliminary 
assessment whether the theory or methodology underlying the 
proposed testimony is sufficiently reliable to reach the trier 
of fact.'"  Commonwealth v. Camblin, 478 Mass. 469, 475 (2017) 
(Camblin II), quoting Commonwealth v. Shanley, 455 Mass. 752, 
761 (2010).   
When considering a motion to introduce expert testimony, a 
judge should initially consider five nonexclusive factors in 
determining the reliability of proposed scientific evidence:  
"whether the scientific theory or process (1) has been 
generally accepted in the relevant scientific community; 
(2) has been, or can be, subjected to testing; (3) has been 
subjected to peer review and publication; (4) has an 
 
16 Although we have adopted the Daubert-Lanigan standard, 
reliability may also be established by the Frye test.  See 
Davis, 487 Mass. at 454 ("reliability can still be established 
by general acceptance alone, without regard to the other 
Daubert-Lanigan factors"); Frye v. United States, 293 F. 1013, 
1014 (D.C. Cir. 1923).  The Commonwealth does not rely on the 
Frye test to establish reliability in this case, however.   
23 
 
unacceptably high known or potential rate of error; and (5) 
is governed by recognized standards."  
  
Commonwealth v. Powell, 450 Mass. 229, 238 (2007).  If a 
methodology has been determined to be reliable by our courts in 
the past, a judge may take judicial notice of its reliability.  
Davis, 487 Mass. at 454-455.  However, "when proposed expert 
testimony uses a new theory, or new methodology to apply an 
accepted theory, the proponent must establish its reliability 
using a Daubert-Lanigan analysis."  Id. at 455.  
Because no court in the Commonwealth has previously deemed 
FLH data to be reliable, the Commonwealth bore the burden of 
establishing the reliability of FLH data under Daubert-Lanigan 
by a preponderance of the evidence.  See Camblin II, 478 Mass. 
at 476.17  We review a trial judge's decision on a motion in 
limine to qualify or reject an expert on Daubert-Lanigan grounds 
for an abuse of discretion.  Canavan's Case, 432 Mass. 304, 312 
(2000).  See L.L. v. Commonwealth, 470 Mass. 169, 185 n.27 
(2014) (discretionary decision constitutes abuse of discretion 
where "the judge made 'a clear error in weighing' the factors 
relevant to the decision, such that the decision falls outside 
the range of reasonable alternatives" [citation omitted]).   
 
17 This also appears to be an issue of first impression, as 
we have not been presented with any cases from other 
jurisdictions addressing the reliability of FLH data. 
 
24 
 
As an initial matter, the Commonwealth argues that the 
trial judge erred in identifying the relevant field of expertise 
as cellular technology, rather than digital forensics.  It 
claims that this error evidences a misunderstanding of FLH data 
and contributed to the trial judge's erroneous conclusion that 
the analyst was not qualified to testify as an expert on FLH 
data.18  Contrary to these claims, we conclude that the trial 
judge correctly understood the analyst's testimony on FLH data, 
and the relevant required expertise, and decided the pertinent 
issue:  whether the Commonwealth had met its burden of 
establishing the reliability, under the Daubert-Lanigan 
standard, of FLH data.  Whether the relevant field of expertise 
is characterized as cellular technology or digital forensics, 
the trial judge did not abuse his discretion in determining that 
the Commonwealth had not met its burden of showing that the 
proffered expert testimony established the reliability of the 
FLH date in this case.  See Camblin II, 478 Mass. at 476.  
i.  General acceptance.  Regarding the first Daubert-
Lanigan factor, general acceptance by the relevant scientific 
community, the trial judge concluded that "[t]here [was] little 
evidence that the process of obtaining and analyzing FLH data 
 
18 Although the Commonwealth suggests that this alleged 
error constitutes an error of law, it cites to no cases in 
support of this claim. 
25 
 
has been generally accepted in the scientific community."  The 
primary evidence in support of general acceptance was the 
analyst's conclusory testimony to that effect, which, as the 
trial judge noted, was not well supported by the evidence in the 
record.  The articles submitted in evidence by the Commonwealth 
in support of the analyst's testimony largely discuss the 
technology that produces the location data points that are used 
as inputs by the FLH algorithm to output FLH data, and do not 
discuss the reliability of the FLH data themselves.  The analyst 
identified two digital forensics experts whose writing he 
claimed supported his conclusion that FLH data have been deemed 
reliable by the scientific community, but no articles by these 
authors were submitted in evidence by the Commonwealth.19  
Accordingly, the trial judge did not abuse his discretion in 
concluding that the Commonwealth failed to meet its burden of 
showing by a preponderance of the evidence that FLH data have 
been generally accepted as reliable by the scientific community.  
 
19 It is not clear why no articles by these authors were 
provided as evidence of general acceptance of FLH data.  We 
note, however, that one of the experts named by the analyst, Ian 
Whiffin, in 2021 wrote, "If I were to find encryptedB location 
data in a case which was relevant to a crime scene, while I 
wouldn't describe it as useless, I would be very wary of saying 
it's the smoking gun."  Whiffin, Harvested Locations, DoubleBlak 
Digital Forensics (Mar. 26, 2021), https://www.doubleblak.com 
/blogPost.php?k=Harvest [https://perma.cc/6QSM-LAAT].  According 
to the analyst's testimony, Encrypted B location data are the 
primary source of location data from which FLH data are 
produced.   
26 
 
See Canavan's Case, 432 Mass. at 310 (party seeking to introduce 
scientific evidence bears burden of showing reliability by 
establishing general acceptance or through other means). 
The Commonwealth also argues that because the FLH algorithm 
uses as its inputs location data sources generally regarded as 
reliable (such as GPS, CSLI, and Wi-Fi location data), the FLH 
data output by the algorithm consequently is also generally 
regarded as reliable.  This argument misunderstands the 
Commonwealth's burden.  "[W]hen proposed expert testimony uses a 
new theory, or new methodology to apply an accepted theory, the 
proponent must establish its reliability using a Daubert-Lanigan 
analysis."  Davis, 487 Mass. at 455.  See Commonwealth v. 
Camblin, 471 Mass. 639, 650 (2015), S.C., 478 Mass. 469 (2017) 
(although breathalyzer technology is generally accepted as 
reliable, where new type of breath test machine had not 
previously been tested and no court had considered the 
reliability of its source code, "the judge should have held a 
hearing to determine whether the source code and other 
challenged features . . . functioned in a manner that reliably 
produced accurate breath test results").  In other words, even 
if the inputs used by the FLH algorithm are generally deemed 
reliable, the FLH data outputs are not ipso facto reliable, 
especially where there is not scientific literature or adequate 
testing to support reliability.  See Davis, 487 Mass. at 457 
27 
 
("It is not sufficient to show merely that GPS technology is, in 
general, reliable without making any showing pertaining to the 
reliability of a particular model of a device" using GPS 
technology).   
ii.  Testing.  As to the second Daubert-Lanigan factor, 
whether the technology can be or has been tested, the trial 
judge did not abuse his discretion in holding that there was not 
sufficient testing to establish the reliability of FLH data.  
The trial judge found that the analyst's experiments with FLH 
data had a small sample size.20  To test the reliability of FLH 
data, the analyst jailbroke an iPhone 5C, which allowed him 
access to information that is ordinarily encrypted and 
inaccessible to an iPhone user.  He brought the jailbroken 
iPhone to five different locations, examined the underlying 
location data points gathered by the iPhone at those locations 
from sources such as CSLI, Wi-Fi, and GPS, and compared these 
underlying location data points to the FLH data outputs produced 
on those locations.  The analyst visited each of the five 
locations two or three times, for a total of twelve 
 
20 The Commonwealth correctly points out that the judge 
misstated the number of tests performed on the test iPhone.  The 
judge stated that there were ten experiments done by the 
analyst, while the analyst testified that he performed twelve 
tests of FLH data reliability at a total of five locations.  
 
  
28 
 
experiments.21  Despite his testing, the analyst did not know the 
algorithm used in creating FLH data and did not know how various 
factors were weighed to create FLH data outputs.  The analyst 
also could not explain how the uncertainty radius for a frequent 
location was determined.  He was able to identify that the 
uncertainty radius and center coordinate point for a frequent 
location could change with each visit to that location, but he 
was unable to explain why the uncertainty radius for a frequent 
location changed or whether data from previous visits 
contributed to how FLH data changed after a subsequent visit to 
the location.  Moreover, while the FLH data for some locations 
included a "confidence level," the analyst could not explain 
what the confidence level meant, why some locations had a 
confidence level and others did not, or how the confidence level 
was calculated.   
The Commonwealth also argues that the trial judge abused 
his discretion by failing to make findings regarding evidence 
that certain frequent location visits identified on the 
 
21 It appears from the record that the analyst performed 
this testing specifically in preparation to testify in these 
proceedings, which warrants closer examination of his expert 
testimony and the validity of these tests.  See Commonwealth v. 
Rintala, 488 Mass. 421, 438 (2021), quoting Johnson v. Manitowoc 
Boom Trucks, Inc., 484 F.3d 426, 434 (6th Cir. 2007) ("judges 
should closely scrutinize expert testimony where the testimony 
is 'prepared solely for purposes of litigation, as opposed to 
testimony flowing naturally from an expert's line of scientific 
research or technical work'"). 
29 
 
defendant's cell phone were corroborated by other data on the 
phone.  The Commonwealth asserts that the data corroborating the 
frequent location data bolsters the analyst's testing as 
evidence that FLH data are reliable.  For example, the analyst 
testified that frequent location no. 73 on the defendant's cell 
phone corresponded to a location at a mall in Newton.  The FLH 
data suggested that the cell phone was at frequent location no. 
73 from 7:26 P.M. to 7:32 P.M. on March 29, 2015, two days 
before the murder.  The uncertainty radius for frequent location 
no. 73 was ninety-one meters, meaning the FLH data represented 
that the cell phone was likely within a ninety-one meter radius 
of the determined center point for location no. 73.  Two images 
recovered from the defendant's cell phone were taken at 7:31 
P.M. and 7:32 P.M. on March 29, and appear to have been taken in 
the northwest corner of the mall parking garage.  The 
Commonwealth suggests that the pictures corroborate the 
reliability of frequent location no. 73 because they place the 
defendant near the location during the relevant time.  The 
analyst testified regarding four other frequent locations 
extracted from the defendant's cell phone that were corroborated 
either by pictures taken on the phone indicating it was in the 
area of the frequent location during the relevant time period, 
or by data showing the phone connected to Wi-Fi networks 
30 
 
associated with a location while the FLH data indicated the 
phone was at the location.22 
Although the trial judge did not make any findings 
regarding the corroborated frequent location evidence presented 
by the Commonwealth, judges are not required to make explicit 
findings on all the evidence presented at a hearing.  See 
Commonwealth v. Tremblay, 480 Mass. 645, 660 (2018) (although 
judges have obligation to make adequate findings, "motion judges 
need not making findings with respect to every piece of evidence 
in the record, irrespective of pertinence").  Although it would 
have been preferable for the judge to make explicit findings 
regarding the corroborated frequent locations, it was not error 
 
22 The evidence did not always unambiguously indicate the 
reliability of the FLH data.  On cross-examination, the analyst 
admitted that the pictures taken in the mall parking garage 
appear to have been taken 272 feet outside the uncertainty 
radius for frequent location no. 73.  The analyst later 
explained that because frequent location no. 73 had been visited 
fourteen times, the center point and uncertainty radius for the 
location could have shifted over time.   
 
The analyst also provided testimony regarding frequent 
location no. 122, which roughly corresponded to the location of 
an apartment complex in Randolph.  The analyst testified that 
the FLH data for frequent location no. 122 showed that the 
defendant's cell phone entered the frequent location at 10:55 
P.M. on March 25, 2015, and left the location at 6:45 A.M. the 
next morning.  The defendant's cell phone connected to Wi-Fi 
networks also associated with the Randolph apartment complex at 
11:17 P.M. on March 25, 2015, as well as 6:45 A.M. on March 26.  
The FLH data would thus suggest that the cell phone left the 
apartment complex the same minute that it connected to a Wi-Fi 
network at the complex on the morning of March 26. 
 
31 
 
for him to omit them from his ruling.23  Even if evidence of the 
five corroborated locations are considered alongside the twelve 
experiments conducted by the analyst, it was well within the 
trial judge's discretion to hold that the Commonwealth had not 
met its burden of showing that FLH data had been sufficiently 
tested to show its reliability.  See Commonwealth v. Rintala, 
488 Mass. 421, 440-441 (2021) (testing was insufficient and 
expert opinion was therefore unreliable where six experiments 
were not repeated or validated).  See also National Research 
Council, Strengthening Forensic Science in the United States:  A 
Path Forward 112 (2009) ("Typically, experiments or observations 
must be conducted over a broad range of conditions before the 
roles of specific factors, patterns, or variables can be 
understood").24 
 
23 We also note that the trial judge had only four days to 
decide the motion to admit FLH data, in part because it appears 
the Commonwealth was unprepared in July 2023 when the hearing 
was originally scheduled to take place.  The time pressure may 
have contributed to the judge's decision not to widen his scope 
of analysis to include explicit findings on the corroborating 
FLH data evidence. 
 
24 State v. Pierce, 222 A.3d 582 (Del. Super. Ct. 2019), 
aff'd, 236 A.3d 307 (Del. 2020), provides an apt comparison.  In 
Pierce, prosecutors sought to admit "Google Wi-Fi location data" 
sent between a cell phone running the Android operating system 
and Google.  Id. at 583.  To support the reliability of the Wi-
Fi location data, an engineer with twenty years of experience 
working at Oracle, a major software firm, testified.  Id. at 
588.  The engineer constructed a "test rig" device containing 
twenty cell phones "which operate[d] as a 'man-in-the-middle' 
exploit to observe the signals sent by the devices to Google."  
32 
 
iii.  Other Daubert-Lanigan factors.  Finally, we consider 
whether the trial judge abused his discretion in his discussion 
of the other Daubert-Lanigan factors:  whether FLH data evidence 
"(3) has been subjected to peer review and publication; (4) has 
an unacceptably high known or potential rate of error; and (5) 
is governed by recognized standards."  Davis, 487 Mass. at 454, 
quoting Powell, 450 Mass. at 238.  It is undisputed that the 
testing of FLH data performed by the analyst was neither peer-
reviewed nor published.  In terms of other publications, the 
trial judge found that the articles and materials submitted by 
 
Id. at 589.  The engineer used the test rig for a period of two 
years and analyzed communications between the cell phones in the 
test rig and Google to determine the accuracy of Wi-Fi location 
data in a variety of locations.  Id.  Additionally, the engineer 
deployed the test rig near the scene of the crime and determined 
that the density of Wi-Fi signals in the area was sufficient to 
reliably identify the location of the defendant's cell phone 
within approximately one hundred feet.  Id.  The extensive 
testing done by an experienced engineer at a major software firm 
over the course of two years is very different from the twelve 
tests conducted by the analyst, even if the corroborating FLH 
data are considered.  To be clear, we do not suggest that the 
exact credentials or testing procedures used in Pierce are what 
would be required to show that FLH data are reliable.  However, 
the comparison to Pierce illustrates that the trial judge did 
not abuse his discretion in holding that the limited testing 
done by the analyst in this case was insufficient to establish 
FLH data reliability.  We further note that the Commonwealth 
argued that the Google Wi-Fi location data found reliable in 
Pierce and the FLH data at issue here are analogous, and thus 
FLH data should be considered reliable.  We certainly cannot, on 
this record, conclude that Wi-Fi location data on the Android 
cell phone operating system are so similar to FLH data that 
Pierce somehow establishes the reliability of the FLH data at 
issue here. 
33 
 
the Commonwealth discussing the underlying technology (GPS, Wi-
Fi, and CSLI) were not "particularly instructive."  He also 
noted that there were "very few references to FLH in any of the 
papers submitted into evidence."  After a review of the articles 
referenced, we agree.  The analyst referenced other experts in 
the field of digital forensics who informed his opinion that FLH 
data are generally regarded as reliable, but no articles written 
by those experts, peer-reviewed or not, appear in the record 
produced by the Commonwealth.  Therefore, the trial judge did 
not abuse his discretion in holding that the Commonwealth had 
failed to show evidence that FLH data have been subjected to 
peer review or publication. 
The trial judge held that the fifth prong of Daubert-
Lanigan, recognized standards, was satisfied by the existence 
and admission in evidence of Federal regulations setting 
standards for analyzing cell phone location information 
generally.  See Matter of E911 Location Accuracy Requirements, 
Fourth Report and Order, 30 F.C.C.R. 1259 (2015).25  The 
Commonwealth argues on appeal that because Federal regulations 
exist for cell phone location information and were in effect at 
the time of the murder, the fourth prong, known or potential 
 
25 We note that such regulations do not address FLH data 
specifically.  We need not, however, resolve whether the fifth 
prong was factored properly to conclude that the reliability of 
FLH data was not established.   
34 
 
rate of error, must also logically be met.  The Commonwealth 
does not otherwise provide any evidence or argument as to why 
the trial judge erred in holding that it had failed to meet its 
burden on the fourth prong.  In any event, we see no abuse of 
discretion by the trial judge in holding that the fourth prong 
was not met, particularly because of the various characteristics 
of FLH data that the analyst could not explain, including the 
uncertainty radius and confidence level.  
 
For the reasons discussed, the trial judge did not abuse 
his discretion in holding the Commonwealth failed to establish 
the reliability of FLH data.  See Davis, 487 Mass. at 455.  The 
judge thus correctly denied the motion to permit the proffered 
expert testimony on FLH data evidence at trial. 
3.  Conclusion.  Because the challenged evidentiary ruling 
involved neither the determination of a motion to suppress nor 
the pretrial exclusion pursuant to a motion in limine of 
evidence that, as a practical matter, would terminate the 
Commonwealth's prosecution of the defendant, the Commonwealth's 
avenue for interlocutory review of the ruling was a petition for 
extraordinary relief under G. L. c. 211, § 3, rather than an 
interlocutory appeal under rule 15 (a) (2).  Moreover, having 
considered the merits of the Commonwealth's petition, we 
conclude that the trial judge did not abuse his discretion in 
denying the Commonwealth's motion in limine to admit the 
35 
 
proffered expert testimony regarding the FLH data.  Accordingly, 
we remand the case to the county court for entry of a judgment 
affirming the trial court judge's order and remanding the matter 
to the trial court for further proceedings consistent with this 
opinion. 
 
 
 
 
 
 
 
So ordered. 
LOWY, J. (concurring, with whom Georges, J., joins).  I 
agree with the court that Mass. R. Crim. P. 15 (a) (2), as 
appearing in 474 Mass. 1501 (2016), was not the proper avenue 
for interlocutory review of the trial judge's ruling, and that 
the trial judge did not abuse his discretion in denying the 
Commonwealth's motion in limine to admit its proffered expert 
testimony on the frequent location history (FLH) data retrieved 
from the defendant's cell phone.  I write separately to 
highlight that, although the trial judge did not abuse his 
discretion in this case in ruling that the Commonwealth failed 
to satisfy the Daubert-Lanigan standard, see Daubert v. Merrell 
Dow Pharms., Inc., 509 U.S. 579, 585-595 (1993); Commonwealth v. 
Lanigan, 419 Mass. 15, 25-26 (1994), a party may well meet its 
burden to show gatekeeper reliability of expert testimony 
regarding FLH data in another pending or future case, see Mass. 
G. Evid. §§ 104(a), 702 (2023). 
Indeed, FLH data -- like all technology -- is an area 
"where knowledge is evolving, and new understandings may be 
expected as more studies and tests are conducted."  Commonwealth 
v. Shanley, 455 Mass. 752, 763 n.15 (2010).  The Commonwealth 
failed to demonstrate here that FLH data can reliably establish 
that an iPhone was in an approximate area at an estimated time 
for several reasons, including the lack of evidence that FLH 
data has been generally accepted in the scientific community, 
2 
 
the absence of articles and peer-reviewed studies offered in 
evidence supporting the reliability of FLH data, the lack of 
information as to whether there is an unacceptably high known or 
potential rate of error for FLH data, the expert's lack of 
knowledge about the algorithm used to create FLH data, and the 
inadequacy of the expert's testing, which had a small sample 
size, was completed over a short time frame and for the purpose 
of this case, and was neither peer-reviewed nor published.  As 
more becomes known about FLH data, a party attempting to prove 
gatekeeper reliability may cure many, if not all, of the 
Commonwealth's deficiencies.  In other words, it is possible 
that a party may not need an expert from Apple to testify about 
the proprietary algorithm creating FLH data to establish 
gatekeeper reliability.  In sum, I write separately to emphasize 
that today's ruling does not dictate the result at a Daubert-
Lanigan hearing in another case based upon either existing or 
evolving technology.  Cf. Commonwealth v. Davis, 487 Mass. 448, 
457-458 (2021), S.C., 491 Mass. 1011 (2023) (Commonwealth failed 
to show that global positioning system evidence could reliably 
demonstrate speed that defendant was moving during crime and 
judge abused his discretion in admitting such evidence, but 
Commonwealth could attempt to lay proper foundation for speed 
evidence on retrial).