Filed 8/31/17

IN THE SUPREME COURT OF CALIFORNIA

AMERICAN CIVIL LIBERTIES UNION
FOUNDATION OF SOUTHERN
CALIFORNIA et al.,

)
)
)
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Petitioners,
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v.
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THE SUPERIOR COURT OF
)
LOS ANGELES COUNTY,
)
)
Respondent;
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COUNTY OF LOS ANGELES et al.,
)
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Real Parties in Interest.
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____________________________________)

S227106
Ct.App. 2/3 B259392

Los Angeles County
Super. Ct. No. BS143004

Real parties in interest, the Los Angeles Police Department (LAPD) of the
City of Los Angeles and the Los Angeles Sheriff’s Department (LASD) of the
County of Los Angeles (collectively, real parties) employ automated license plate
reader (ALPR) technology in order to locate vehicles linked to crimes under
investigation. The American Civil Liberties Union Foundation of Southern
California (ACLU) and Electronic Frontier Foundation (collectively, petitioners)
filed a request under the California Public Records Act (CPRA) for all ALPR data

 collected during a one-week period. (Gov. Code, § 6250 et seq.)1 Petitioners
sought disclosure of this ALPR data “so that the legal and policy implications of
the government’s use of ALPRs to collect vast amounts of information on almost
exclusively law-abiding [citizens of Los Angeles] may be fully and fairly
debated.”
We initially granted review to determine whether the requested ALPR data
are exempt from disclosure as falling within the CPRA provision protecting police
and state “[r]ecords of . . . investigations” under section 6254, subdivision (f)
(section 6254(f)). As relevant here, section 6254(f) protects from disclosure:
“Records of investigations conducted by . . . any state or local police agency.”2
After granting review, we requested additional briefing on a second issue:
Whether the catchall exemption in section 6255, subdivision (a) (section 6255(a))
authorizes real parties to withhold the requested ALPR data. Under section
6255(a), a public agency may “justify withholding any record by demonstrating
that on the facts of the particular case the public interest served by not disclosing
the record clearly outweighs the public interest served by disclosure of the
record.”
Petitioners conceded in the trial court that section 6254(f) protects from
disclosure the ALPR license plate scan data that matches vehicles linked to law
enforcement investigations under section 6254(f). They do not argue that real
parties’ use of the ALPR technology is unlawful. They contend only that ALPR
scan data are not exempt from disclosure under the CPRA.

1

All further statutory references are to the Government Code, unless
otherwise specified.
2
There is no dispute that ALPR data are public records (see § 6252, subd.
(e)) and no dispute that real parties are police agencies subject to the CPRA.

2

 The trial court determined that the data requested came within section
6254(f)’s “[r]ecords of . . . investigations” exemption. The court also concluded
that section 6255(a)’s catchall provision authorized real parties to withhold the
data. The Court of Appeal affirmed the judgment based on section 6254(f),
without reaching the section 6255(a) question. In light of our constitutional
obligation to broadly construe the CPRA in a manner that furthers the people’s
right of access to the conduct of governmental operations, and to narrowly
construe any exemptions (Cal. Const., art. I, § 3, subd. (b)(2)), we disagree with
the trial court and the Court of Appeal that the ALPR scan data at issue here are
subject to section 6254(f)’s exemption for records of investigations. In addition,
although we agree with the trial court that the public interest in nondisclosure of
raw ALPR scan data clearly outweighs the public interest in disclosure of such
data (§ 6255(a)), we remand for further consideration of whether the raw data may
reasonably be anonymized or redacted such that the balance of interests would
shift and disclosure of the data would be required under the CPRA.
BACKGROUND
The relevant facts are generally not in dispute. The ALPR data collection
system at issue here utilizes high-speed computer-controlled cameras mounted on
fixed structures or on patrol cars. The cameras automatically capture an image of
the license plate of each vehicle that passes through their optical range. For each
image, the ALPR system uses character recognition software and almost instantly
checks the license plate number against a list of license plate numbers that have
been associated with crimes, child abduction AMBER alerts, or outstanding
warrants. This list of license plate numbers comprises the investigative “hot list.”
When a hot list match occurs, the system alerts either officers in a patrol car or a
central dispatch unit, depending on whether the ALPR unit that detects a match is
mounted on a patrol car or a fixed structure. Most license plate numbers that
3

 ALPR units capture do not match the hot list and have no perceived connection to
any crimes, AMBER alerts, or outstanding warrants.3
The ALPR technology records each scanned license plate number, together
with the date, time, and location of the scan, and stores the data on confidential
computer networks. LAPD estimates that it records data from 1.2 million cars per
week. It retains license plate scan data for five years. LASD estimates that it
records between 1.7 and 1.8 million license plates per week. It retains scan data
for two years. When new investigations arise, real parties query their stored
databases to obtain any available location history of relevant vehicles. Both the
LAPD and LASD restrict database access to law enforcement.
On August 30 and September 4, 2012, petitioners sent substantially
identical requests under the CPRA to each of the real parties, seeking “records
related to those agencies’ use of ALPR technology, including ‘all ALPR data
collected or generated’ during a one-week period in August 2012, consisting of,
‘at a minimum, the license plate number, date, time, and location information of
each license plate recorded.’ ” Real parties withheld the requested plate scan data,
citing the exemption for law enforcement records of investigations under section
6254(f). Petitioners did not seek disclosure of the hot list itself or records of which
license plate numbers matched the hot list.
Petitioners’ CPRA request also sought disclosure of “any policies,
guidelines, training manuals and/or instructions on the use of ALPR technology
and the use and retention of ALPR data, including records on where the data is
stored, how long it is stored, who has access to the data, and how long they access
the data.” Real parties agreed to produce these records.
According to petitioners, “Typically, only about 0.2% of plate scans are
connected to suspected crimes or vehicle registration.”
3

4

 On May 6, 2013, petitioners filed a petition for writ of mandate in the Los
Angeles County Superior Court to compel disclosure of the requested ALPR data.
In opposing the petition, real parties cited the exemption for records of
investigation under section 6254(f) as well as the catchall public interest
exemption under section 6255(a). After a hearing, the superior court
acknowledged the intrusive nature of license plate scanning as well as its potential
for abuse. The court concluded, however, that all of the requested data were
exempt from disclosure under both sections 6254(f) and 6255(a).
Petitioners sought issuance of an extraordinary writ in the Court of Appeal.
After conducting a de novo review (§ 6259, subd. (c)), the Court of Appeal
affirmed the trial court’s judgment, holding all data exempt from disclosure under
section 6254(f). The Court of Appeal did not discuss either section 6255(a)’s
balancing test or that statute’s potential application to any of the scan data.
DISCUSSION
1. The CPRA
The Legislature enacted the CPRA in 1968. (Stats. 1968, ch. 1473, § 39, p.
2964.) It was modeled after the 1967 federal Freedom of Information Act (5
U.S.C. § 552). (Los Angeles County Bd. of Supervisors v. Superior Court (2016) 2
Cal.5th 282, 290.) The CPRA explains that “access to information concerning the
conduct of the people’s business is a fundamental and necessary right of every
person in this state.” (§ 6250.) To promote this fundamental right, the CPRA
provides that “every person has a right to inspect any public record, except as
hereafter provided.” (§ 6253, subd. (a).) “In other words, all public records are
subject to disclosure unless the Legislature has expressly provided to the
contrary.” (Williams v. Superior Court (1993) 5 Cal.4th 337, 346 (Williams).)
Proposition 59, a measure submitted to the voters in 2004, enshrined the
CPRA’s right of access in the state Constitution: “The people have the right of
5

 access to information concerning the conduct of the people’s business, and,
therefore, the meetings of public bodies and the writings of public officials and
agencies shall be open to public scrutiny.” (Cal. Const., art. I, § 3, subd. (b)(1),
added by Prop. 59, approved by voters, Gen. Elec. (Nov. 2, 2004).) The state
Constitution implemented this right of access with the general directive that a
“statute, court rule, or other authority . . . shall be broadly construed if it furthers
the people’s right of access, and narrowly construed if it limits the right of access.”
(Cal. Const., art. I, § 3, subd. (b)(2).) Although the CPRA provides for a broad
right of access, it “recognizes that certain records should not, for reasons of
privacy, safety, and efficient governmental operation, be made public”—including
certain records of investigations exempted under section 6254(f). (Haynie v.
Superior Court (2001) 26 Cal.4th 1061, 1064 (Haynie).) We turn first to the scope
of that exemption.
2. Application of section 6254(f)
Section 6254(f) exempts from mandatory disclosure certain “[r]ecords
of . . . investigations conducted by, or records of intelligence information or
security procedures of, . . . any state or local police agency,” as well as certain
“investigatory or security files.” (§ 6254(f).) This case requires us to construe the
exemption for records of investigations, rather than investigatory files (Williams,
supra, 5 Cal.4th at p. 341) or intelligence information (American Civil Liberties
Union Foundation v. Deukmejian (1982) 32 Cal.3d 440, 443 (Deukmejian)).
Our interpretation of the phrase “[r]ecords of . . . investigations” is guided
by familiar principles of statutory interpretation, as well the “constitutional
imperative” to construe CPRA in a manner that furthers disclosure. (City of San
Jose v. Superior Court (2017) 2 Cal.5th 608, 616–617 (City of San Jose); see
Sierra Club v. Superior Court (2013) 57 Cal.4th 157, 166.) The parties point us
toward various dictionary definitions that they believe advance their positions.
6

 Real parties observe, for example, that Black’s Law Dictionary defines the term
“investigate” to mean “[t]o inquire into (a matter) systematically” or “[t]o make an
official inquiry.” (Black’s Law Dict. (9th ed. 2009), p. 902.) This definition and
the others suggested are not specific to the law enforcement or CPRA contexts,
however, and afford us only minimal guidance about the meaning of the statutory
text. It is enough to say that the definitions of which we are aware do not compel
(or even strongly suggest) an answer to the question before us. A closer
examination of the CPRA’s context, including the presumption in favor of access,
is required.
We previously construed the records of investigations exemption in Haynie,
supra, 26 Cal.4th 1061. Elgin Haynie claimed that he was injured by a Los
Angeles County Deputy Sherriff during a traffic stop and sought certain public
records regarding the incident. (Id. at p. 1065.) The sheriff’s department refused
to provide those records, instead disclosing a “ ‘summary of the event,’ ” which
asserted that the Deputy “ ‘received a call from a neighbor who saw several males
carrying guns enter an older model dark blue Ford van and travel down the road.
The deputy spotted a vehicle matching that description five minutes later and he
decided to conduct an investigation of the van.’ ” (Id. at pp. 1065–1066.) The
department asserted that the “[r]ecords of . . . investigations” exemption mooted
CPRA disclosure. (§ 6254, subd. (f).) Among other things, Haynie responded that
“ ‘records of investigations’ should be defined so as to exclude investigations that
are merely ‘routine’ or ‘everyday police activity,’ such as his traffic stop.”
(Haynie, supra, 26 Cal.4th at p. 1070.)
We disagreed. (See Haynie, supra, 26 Cal.4th at pp. 1070–1071.) In doing
so, we discussed the risk that Haynie’s proposed interpretation might pose to law
enforcement operations. “Complainants and other witnesses whose identities were
disclosed might disappear or refuse to cooperate. Suspects, who would be alerted
7

 to the investigation, might flee or threaten witnesses. Citizens would be reluctant
to report suspicious activity. Evidence might be destroyed.” (Id., at pp. 1070–
1071.) We also stressed, however, that “by including ‘routine’ and ‘everyday’
within the ambit of ‘investigations’ in section 6254(f), we [did] not mean to shield
everything law enforcement officers do from disclosure. [Citation.] Often,
officers make inquiries of citizens for purposes related to crime prevention and
public safety that are unrelated to either civil or criminal investigations. The
records of investigation exempted under section 6254(f) encompass only those
investigations undertaken for the purpose of determining whether a violation of
law may occur or has occurred. If a violation or potential violation is detected, the
exemption also extends to records of investigations conducted for the purpose of
uncovering information surrounding the commission of the violation and its
agency. Here, the investigation that included the decision to stop Haynie and the
stop itself was for the purpose of discovering whether a violation of law had
occurred and, if so, the circumstances of its commission. Records relating to that
investigation are exempt from disclosure by section 6254(f).” (Haynie, supra, at
p. 1071, italics added.)
The facts of Haynie are quite unlike the facts here. Haynie concerned an
individual deputy stopping an individual driver, allegedly based on a single, close
in time tip from a neighbor. This case concerns the collection of enormous
amounts of bulk data. But Haynie at least implies that an inquiry must be
somewhat targeted at suspected violations of law (see Haynie, supra, 26 Cal.4th at
p. 1071) to qualify as an “investigation[]” under section 6254(f). The mere fact of
an inquiry is not enough.
Our case law recognizes that the CPRA should be interpreted in light of
modern technological realities. (Cf. City of San Jose, supra, 2 Cal.5th at pp. 618–
619 & fn. 4.) It is hard to imagine that the Legislature intended for the records
8

 of investigations exemption to reach the large volume of data that plate scanners
and other similar technologies now enable agencies to collect indiscriminately.
Nothing in the text or structure of the statute suggests an effort to imbue the term
with a meaning that capacious. Indeed, section 6254(f) itself authorizes disclosure
of certain portions of records of investigations, such as certain “names and
addresses of persons involved in, or witnesses other than confidential informants
to, the incident.” (Italics added.) This language suggests that the Legislature did
not contemplate “investigation” of hundreds or thousands of individuals
simultaneously—nor, more to the point, an exemption that would cover all data
collected during such a far-reaching inquiry.
Of course, the mere fact that the technology for such mass data collection
was not in use when the Legislature enacted CPRA does not answer the question
before us. As Fourth Amendment jurisprudence illustrates, a provision can apply
to new and perhaps unanticipated technologies when the purpose behind the
provision will be served. (Cf. Katz v. United States (1967) 389 U.S. 347, 353
[wiretaps of phone booths are searches for Fourth Amendment purposes because
they impinge on the privacy interests the amendment was designed to protect].)
As we recognized in Haynie, however, the animating concern behind the records
of investigations exemption appears to be that a record of investigation reveals
(and, thus, might deter) certain choices that should be kept confidential––an
informant’s choice to come forward, an investigator’s choice to focus on particular
individuals, the choice of certain investigatory methods. Such choices are far less
likely to be revealed where, as here, data are collected en masse. True, the
collection of ALPR data can shed light on certain choices, for example, that data
are being collected disproportionately in certain neighborhoods. But this kind of
revelation seems far less likely to compromise current or future law enforcement,
and thus far less likely to prompt the concerns animating section 6254(f).
9

 Not only are the concerns underlying the exemption only weakly implicated
by the disclosure of the ALPR data, but broadly exempting the data would inflict a
far greater blow to the public interest in disclosure than does exempting records
concerning more traditional investigations. For example, if all that mattered were
whether an agency sought to collect information in connection with a crime (as
opposed to no crime at all), real parties could reduce the hot list to a single license
plate number, scan literally every plate in Los Angeles, and be able to assert that
all of the data collected were exempt from CPRA disclosure as an “investigation”
regarding that single plate. In light of CPRA’s purpose of providing access to
information regarding government activities, we doubt that the records
of investigations exemption was intended to stretch that far.
Perhaps the most critical point, however, is one that the Court of Appeal
did not mention: Our constitution requires that CPRA exemptions be narrowly
construed, including the exemption for “[r]ecords of . . . investigations.”
(§ 6254(f).) Even before Proposition 59 was enacted, we recognized that not
every inquiry is an “investigation” in the relevant sense. (See Haynie, supra, 26
Cal.4th at pp. 1070-1071.)
Accordingly, we hold that real parties’ process of ALPR scanning does not
produce records of investigations, because the scans are not conducted as part of a
targeted inquiry into any particular crime or crimes. The scans are conducted with
an expectation that the vast majority of the data collected will prove irrelevant for
law enforcement purposes. We recognize that it may not always be an easy task to
identify the line between traditional “investigation” and the sort of “bulk”
collection at issue here. But wherever the line may ultimately fall, it is at least
clear that real parties’ ALPR process falls on the bulk collection side of it.
Nor does the act of querying the database for information on particular
vehicles transform existing ALPR scan records into exempt “[r]ecords of . . .
10

 investigations” (§ 6254(f)). A plate scan in itself always remains a result of bulk
data collection, rather than a record of investigation, even if it has the potential to
match a future search query. The fact that a database has been searched or that a
plate in the database has been matched in a search does not increase the concerns
identified in Haynie with respect to disclosure of the database. Moreover, a
contrary rule would enable an agency to exempt such data, purportedly to advance
some more traditional “investigation,” simply by searching the entire database.
Therefore, the bulk collection of raw ALPR data here is not exempt from
disclosure under section 6254(f). We do not decide, however, whether an ALPR
record that later becomes part of a more targeted investigation might properly be
addressed under the investigatory file exemption (§ 6254(f)) which applies to
certain “materials that relate to the investigation” if there is a “concrete and
definite prospect of enforcement proceedings.” (Williams, supra, 5 Cal.4th at p.
362; compare Haynie, supra, 26 Cal.4th at pp. 1068-1069 [records of investigation
exemption does not require concrete and definite prospect of enforcement].) We
next consider whether the ALPR raw data may be withheld under section 6255(a).
3. Application of section 6255(a)
Section 6255(a)—CPRA’s catchall provision (see Los Angeles County Bd.
of Supervisors v. Superior Court, supra, 2 Cal.5th at p. 291)—permits an agency
to withhold a public record if the agency demonstrates “that on the facts of the
particular case the public interest served by not disclosing the record clearly
outweighs the public interest served by disclosure of the record.” (§ 6255(a).)
(See, e.g., Deukmejian, supra, 32 Cal.3d at pp. 452–454 [construing the
application of the catchall provision].) This “provision contemplates a case-bycase balancing process, with the burden of proof on the proponent of
nondisclosure to demonstrate a clear overbalance on the side of confidentiality.”
(Michaelis, Montanari & Johnson v. Superior Court (2006) 38 Cal.4th 1065, 1071
11

 (Michaelis).) Whether such an overbalance exists may depend on a wide variety
of considerations, including privacy (City of San Jose, supra, 2 Cal.5th at p. 626);
public safety (Long Beach Police Officers Assn. v. City of Long Beach (2014) 59
Cal.4th 59, 74 (Long Beach)); and the “expense and inconvenience involved in
segregating nonexempt from exempt information.” (Deukmejian, supra, 32 Cal.3d
at pp. 452–453). In balancing the interests for and against disclosure, we review
the public interest factors de novo but accept the trial court’s factual findings as
long as substantial evidence supports them. (Michaelis, 38 Cal.4th at p. 1072; see
CBS, Inc. v. Block (1986) 42 Cal.3d 646, 650-651 (CBS).)
The trial court determined that the balance of interests under section
6255(a) weighed clearly against disclosure of raw ALPR scan data. We agree.
The trial court further determined, however, that even anonymized or redacted
plate scan data could be withheld. Because the trial court erred in reaching this
conclusion based on the present record, and because the inquiry requires additional
factual development, we will remand for further proceedings.
a. Unaltered plate scan data
As noted, petitioners seek disclosure of unaltered plate scan data, including,
“ ‘at a minimum, the license plate number, date, time, and location information of
each license plate recorded.’ ” Petitioners contend that, among other things, these
data could reveal whether law enforcement officers are using ALPR technology to
target particular individuals, neighborhoods, or organizations. The data could also
shed light on the degree to which ALPR technology threatens individual privacy
interests.
The trial court carefully considered these interests. It also recognized,
however, that disclosing unaltered plate scan data to the public threatens
individuals’ privacy. ALPR data showing where a person was at a certain time
could potentially reveal where that person lives, works, or frequently visits.
12

 ALPR data could also be used to identify people whom the police frequently
encounter, such as witnesses or suspects under investigation (albeit to a lesser
extent than in the type of situation at issue in Haynie). In short, as the trial court
observed, “Members of the public would be justifiably concerned about LAPD or
LASD releasing information regarding the specific locations of their vehicles on
specific dates and times to anyone.” Although we acknowledge that revealing raw
ALPR data would be helpful in determining the extent to which ALPR technology
threatens privacy, the act of revealing the data would itself jeopardize the privacy
of everyone associated with a scanned plate. Given that real parties each conduct
more than one million scans per week, this threat to privacy is significant. We
therefore conclude that the public interest in preventing such disclosure “clearly
outweighs the public interest served by disclosure of” these records. (§ 6255(a).)4
b. Anonymized or redacted plate scan data
The trial court also considered whether the balance of interests at stake
might be altered if ALPR data were anonymized: “for example plate ‘G5123AP’
could have a random number ‘1111111’ assigned to it.” The court assumed for
argument’s sake that this possibility was “both workable and inexpensive.” It
rejected the possibility that anonymization of the ALPR data would alter the
balance of interests, reasoning that anonymization “would address the individual
privacy concerns, but it would not address the impact on law enforcement
investigation.” We conclude that the trial court placed too much weight on the

4

Recently enacted Civil Code section 1798.90.5 et seq. does not mention the
CPRA, and we do not decide its substantive application here except to note that it
prohibits public agencies from selling, sharing, or transferring ALPR data “except
to another public agency, and only as otherwise permitted by law.” (Id.,
§ 1798.90.52, subd. (a), added by Stats. 2015, ch. 532, § 3, eff. Jan. 1, 2016.) The
statute imposes civil fines for its violations. (Ibid.)

13

 mere possibility that law enforcement efforts would be frustrated. Because this
issue appears to require further factual development, however, we decline to
resolve it in the first instance.
The trial court’s concerns about interference with law enforcement were
multifaceted. The court initially concluded that even if ALPR data were
anonymized before release, “[a] criminal could still use [that] data to follow law
enforcement patrol patterns and still could locate a particular randomized plate at a
particular location on specific days and times.”
The trial court appears to have placed significant weight on the possibility
that a criminal could use ALPR data to identify law enforcement patrol patterns.
The court did so based on the declaration of LAPD Sergeant Daniel Gomez. In
pertinent part, Sergeant Gomez claimed that an individual requesting ALPR data
“could use the data to try and identify patterns of a particular vehicle.” (Italics
added.) However, Sergeant Gomez also seemed to cast doubt on the likelihood
that an individual could do so successfully, explaining that “[u]nlike law
enforcement that uses additional departmental resources to validate captured
[A]LPR information, a private person would be basing their assumptions solely on
the data created by the [A]LPR system . . . .” Nevertheless, we will assume, as the
trial court found, that a person could at least roughly infer patrol patterns from a
week’s worth of plate scan data.
The problem with this aspect of the trial court’s analysis is that, even
assuming patrol patterns can be inferred from ALPR data, there is little reason to
believe that this possibility points meaningfully toward “a clear overbalance on the
side of confidentiality” with respect to all the records sought. (Michaelis, supra,
38 Cal.4th at p. 1071.) For one thing, fixed ALPR scanners are just that—fixed—
so concerns about patrol patterns are inapplicable to the data they collect. For
another, the record does not appear to indicate that knowledge of where law
14

 enforcement officers were during a particular week is a reliable guide to where
they will be at some precise moment in the future. The trial court did not find, for
example, that real parties conduct law enforcement in the same way that they
might operate a bus service—moving from point to point at particular times on
particular days, never deviating to attend to other business or emergencies. We
are not aware of substantial evidence that would have supported such a finding.
Likewise, the court did not determine how often any such routes change, nor
whether the addition of new mobile scanners would make it challenging to infer
that the absence of a patrol route in the past meant the absence of a patrol route in
the future.
The trial court’s judgment appears to rest on an additional error. The court
concluded that “an officer may make a hot list inquiry into the ALPR system and
receive a hit at any time, thereby converting a non-specific scan to evidence in an
individualized investigation. Segregation of records in a fluid computerized
environment is virtually impossible.” This conclusion was also based on the
declaration of Sergeant Gomez, who asserted that LAPD’s system “does not have
the capability as a native function to segregate data based on specific parameters.”
(Italics added.) At the least, the trial court was mistaken to the extent it suggested
that the burden of segregating records that might become exempt is relevant.
Section 6255(a)’s balancing analysis considers the “expense and inconvenience
involved in segregating nonexempt from exempt information.” (Deukmejian,
supra, 32 Cal.3d 440, 452–453.) If a record is not presently exempt from
disclosure, then an agency is not permitted to segregate and withhold it.
Moreover, a plate scan does not become exempt merely because it later surfaces in
a search of an ALPR database
The critical point is that a court applying section 6255(a) cannot allow
“[v]ague safety concerns” to foreclose the public’s right of access. (Long Beach,
15

 supra, 59 Cal.4th at p. 74; cf. CBS, supra, 42 Cal.3d at p. 652 [“A mere assertion
of possible endangerment does not ‘clearly outweigh’ the public interest in access
to these records.”].) The trial court appears to have placed significant weight on
speculative concerns about possible disclosure of mobile ALPR patrol patterns,
without record evidence to support its conclusions. The court erred in doing so.
Notwithstanding our disagreement with the trial court’s reasoning, we do
not have a sufficient factual record to determine whether section 6255(a)’s catchall
exemption applies. We therefore will remand for further proceedings. On
remand, the trial court should conduct a new balancing analysis—one that includes
consideration of the feasibility of, and interests implicated by, methods of
anonymization petitioners have suggested. The trial court is free to explore other
methods of anonymization and redaction as well.
Petitioners have described two anonymization procedures. The first is the
substitution method discussed above: replacing actual license plate numbers with
fictional numbers. Presumably, each plate would be assigned its own unique
(fictional) number, because assigning a random number to each scan, even if
multiple scans concern the same plate, would be no more informative than simply
removing the plate numbers altogether. In exploring this possibility, the court
should evaluate the risk that a plate number could be inferred from a fictional
number. For example, if plate number “1111111” were repeatedly scanned in
front of an office building during the day time, and an apartment building at night,
it might be possible to infer the true owner of plate “1111111” and to track their
other movements. A second method would call for disclosure of two sets of
ALPR data: one that discloses the number of times that each license plate has
been scanned, and another that contains only the time, date, and location of the
scans.

16

 With respect to the concern that patrol patterns might be discerned from the
anonymized data, petitioners suggest different ways to redact the exact date and
time of the scans, so that disclosed records would show a “heat map” of where
scans were taken during the week of data petitioners seek, without revealing as
much information about the mobile units that collected the scans or the license
plates that were subject to them. We note, however, as discussed above, that the
current record provides little, if any, support for the concern that the data would
enable private individuals to discern patrol patterns. Without such information, it
is difficult to see what public interest in nondisclosure could clearly outweigh the
public interest in disclosure of this redacted information, but we leave the issue for
the trial court to resolve.
The anonymization and redaction methods we discuss may be more feasible
than the trial court appeared to believe. Petitioners contend that, even using real
parties’ information system, it takes just “two computer clicks to export license
plate data onto a spreadsheet or other type of document, which the parties can then
modify.” Accordingly, the trial court’s analysis should go beyond whether a
method of removing exempt information is “a native function” of “[t]he system
utilized by the LAPD.” While real parties may not have designed their system to
facilitate CPRA disclosure as a “native function,” randomizing license plate
numbers or deleting columns from a spreadsheet, for example, would seem to
impose little burden. We leave the precise balance between effective
anonymization and redaction and burden to the trial court on remand. We remind
the trial court and the parties, however, that if the anonymized or redacted data are
ultimately released, the courts may exercise no restraint on how the data may be
used apart from the restrictions placed on its dissemination under Civil Code
section 1798.90.5 et seq. (See Deukmejian, supra, 32 Cal.3d at p. 451.)

17

 CONCLUSION
We affirm the Court of Appeal judgment insofar as it exempted raw ALPR
data from CPRA disclosure. We reverse the Court of Appeal judgment insofar as
it rendered anonymized or redacted ALPR data exempt from disclosure. We
remand the action to the Court of Appeal with instructions to remand the matter to
the trial court for further proceedings under section 6255(a) that are consistent
with this opinion.
CHIN, J.
WE CONCUR:
CANTIL-SAKAUYE, C. J.
WERDEGAR, J.
CORRIGAN, J.
LIU, J.
CUÉLLAR, J.
KRUGER, J.

18

 See last page for addresses and telephone numbers for counsel who argued in Supreme Court.
Name of Opinion American Civil Liberties Union Foundation of Southern California v. Superior Court
__________________________________________________________________________________
Unpublished Opinion
Original Appeal
Original Proceeding
Review Granted XXX 236 Cal.App.4th 673
Rehearing Granted
__________________________________________________________________________________
Opinion No. S227106
Date Filed: August 31, 2017
__________________________________________________________________________________
Court: Superior
County: Los Angeles
Judge: James C. Chalfant
__________________________________________________________________________________
Counsel:
Peter Bibring and Catherine A. Wagner for Petitioner American Civil Liberties Union Foundation of
Southern California.
Jennifer Lynch for Petitioner Electronic Frontier Foundation.
Katie Townsend for the Reporters Committee for Freedom of the Press, American Society of News Editors,
Association of Alternative Newsmedia, California Newspaper Publishers Association, Californians Aware,
The Center for Investigative Reporting, First Amendment Coalition, Los Angeles Times Communications
LLC, The McClatchy Company, The National Press Club, National Press Photographers Association,
Online News Association and Society of Professional Journalists as Amici Curiae on behalf of Petitioners.
First Amendment Project, James R. Wheaton and Cherokee D.M. Melton for Northern California Chapter
of the Society of Professional Journalists as Amicus Curiae on behalf of Petitioners.
Marc Rotenberg, Alan Butler, Jeramie Scott and Aimee Thomson for Electronic Privacy Information
Center as Amicus Curiae on behalf of Petitioners.
Jason D. Russell and Richard A. Schwartz for Senator Jerry Hill as Amicus Curiae on behalf of Petitioners.
No appearance for Respondent.
Jones & Mayer, Martin J. Mayer, James R. Touchstone and Deborah Pernice-Knefel for California State
Sheriffs’ Association, California Police Chiefs’ Association and California Peace Officers’ Association as
Amici Curiae on behalf of Respondent.
Michael N. Feuer, City Attorney (Los Angeles), Carlos de La Guerra, Managing Assistant City Attorney,
Debra L. Gonzales and Amy Jo Field, Assistant City Attorneys, Lisa S. Berger and Heather L. Aubry,
Deputy City Attorneys, for Real Parties in Interest City of Los Angeles and Los Angeles Police
Department.

 Page 2 – S227106 – counsel continued
Counsel:
Collins Collins Muir + Stewart, Eric Brown, Tomas A. Guterres and James C. Jardin for Real Parties in
Interest County of Los Angeles and Los Angeles Sheriffs’ Department.
Colantuono, Highsmith & Whatley, Aleksan R. Giragosian, Michael G. Colantuono and Michael R.
Cobden for League of California Cities and California State Association of Counties as Amici Curiae on
behalf of Real Parties in Interest.

 Counsel who argued in Supreme Court (not intended for publication with opinion):
Peter Bibring
ACLU Foundation of Southern California
1313 West Eighth Street
Los Angeles, CA 90017
(213) 977-5295
Heather L. Aubry
Deputy City Attorney
200 North Main Street, Room 800
Los Angeles, CA 90012
(213) 978-6956
James C. Jardin
Collins Collins Muir + Stewart
1100 El Centro Street
South Pasadena, CA 91030
(626) 243-1100