ACLU Immigrants’ Rts. Project v. ICE

21-1233
ACLU Immigrants’ Rts. Project v. ICE
1
In the
United States Court of Appeals
for the Second Circuit
A UGUST TERM 2021
No. 21-1233
A MERICAN C IVIL L IBERTIES U NION IMMIGRANTS ’ R IGHTS PROJECT,
Plaintiff-Appellant,
v.
U NITED S TATES IMMIGRATION AND C USTOMS E NFORCEMENT,
Defendant-Appellee.
__________
ARGUED: MAY 18, 2022
D ECIDED: JANUARY 26, 2023
__________
Before: R AGGI, WESLEY , and CARNEY , Circuit Judges.
________________
In this action under the Freedom of Information Act (“FOIA”),
plaintiff appeals an award of summary judgment in the United States
District Court for the Southern District of New York (George B.
Daniels, Judge) in favor of defendant, arguing that the district court
erred in concluding that requiring defendant to substitute Unique
Identifying Numbers (“Unique IDs”) for FOIA-exempt agency Alien
Identification Numbers (“A-Numbers”) in order to afford plaintiff
access to non-exempt agency records in a person-centric manner
constituted the impermissible creation of new records. In the

-- 1 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
2
particular circumstances of this case, we reject the district court’s
conclusion. A government agency cannot make an exempt record
(here, A-Numbers), the sole “key” or “code” necessary to access non-
exempt records in a particular manner; itself use the exempt record to
obtain non-exempt records in that manner; and then invoke the
record’s exempt status to deny the public similar access to the non-
exempt records. Where an agency chooses to assign exempt records
such a code function within its computer system, FOIA’s broad
disclosure policy obligates the agency to substitute a different code in
order to afford the public non-exempt records in the same manner as
they are available to the agency. That conclusion particularly obtains
here, where the substitute code can be neutral Unique IDs consisting
of any combinations of numbers, letters, or symbols that are
meaningless in themselves and that function only to afford access to
the non-exempt records in the requested manner.
REVERSED AND R EMANDED.
_________________
NOOR Z AFAR , American Civil Liberties
Union Immigrants’ Rights Project, New
York, NY (Michael Tan; Cody Wofsy,
American Civil Liberties Union Immigrants’
Rights Project, San Francisco, CA; Carmen
G. Iguina Gonzalez, American Civil
Liberties Union Immigrants’ Rights Project,
Washington, DC, on the brief), for Plaintiff-
Appellant.
Z ACHARY B ANNON, Assistant United States
Attorney (Benjamin H. Torrance, Assistant

-- 2 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
3
United States Attorney, on the brief), for
Damian Williams, United States Attorney
for the Southern District of New York, New
York, NY, for Defendant-Appellee.
EMILY J. CREIGHTON, American Immigration
Council, Washington, DC, for Amici Curiae
The American Immigration Council,
Citizens for Responsibility and Ethics in
Washington, Emily Ryo, Ingrid Eagly, Tom
Wong, American Oversight, Open the
Government, National Immigrant Justice
Center, National Immigration Project of the
National Lawyers Guild, and Refugee and
Immigrant Center for Education and Legal
Services, in support of Plaintiff-Appellant.
D AVID G REENE , Electronic Frontier
Foundation, San Francisco, CA, for Amicus
Curiae Electronic Frontier Foundation, in
support of Plaintiff-Appellant.
MASON A. K ORTZ , Harvard Law School,
Cambridge, MA, for Amici Curiae The
Center for Investigative Reporting, The
Media Law Resource Center, Inc., and The
MuckRock Foundation, in support of
Plaintiff-Appellant.
_________________
REENA R AGGI, Circuit Judge:
Plaintiff American Civil Liberties Union Immigrants’ Rights
Project (“ACLU”) brought this Freedom of Information Act (“FOIA”)
suit in the United States District Court for the Southern District of

-- 3 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
4
New York (George B. Daniels, Judge) to compel defendant, United
States Immigration and Customs Enforcement (“ICE”), to produce
agency records in the form of electronic spreadsheet data pertaining
to five stages of the immigration enforcement and deportation
process. While ICE produced 21 spreadsheets of responsive data, the
agency did not comply with ACLU’s request to replace exempt Alien
Identification Numbers (“A-Numbers”)1 on such spreadsheets with
anonymized unique identifiers (“Unique IDs”). ACLU submits that
such Unique IDs could be any combinations of numbers, letters, or
symbols that, while meaningless in themselves, would allow ACLU
to track datapoints pertaining to individual (but unidentified) aliens
across ICE databases. On March 10, 2021, the district court granted
ICE’s motion for summary judgment, ruling that ACLU’s requested
substitution effectively required ICE to create new records, something
the court was powerless to order under FOIA. See ACLU Immigrants’
Rts. Project v. ICE, No. 19-CV-7058, 2021 WL 918235 (S.D.N.Y. Mar. 10,
2021).
For the reasons stated herein, we conclude that ICE was not
entitled to summary judgment in the particular circumstances of this
case. In reaching that conclusion, we are mindful that ICE has chosen
to organize its electronic databases by immigration events (e.g.,
arrests, detentions, deportations, etc.), rather than by individual
1 “An A-Number is a unique number assigned to any alien immigrating to
the United States by the Department of Homeland Security,” of which ICE
is a part. Vassilio-Diaz Decl. ¶ 20.

-- 4 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
5
aliens.2 We are further mindful that ICE has chosen—although it was
not required—to have FOIA-exempt A-Numbers function as the sole
“key” or “code” affording access to electronic data pertaining to
individual aliens from its event-centric databases, and that ICE itself
uses A-Numbers for that purpose. Thus, by here redacting A-
Numbers from the spreadsheets it produced conveying datapoints by
event rather than by person, ICE not only shielded the FOIA-exempt
personal identifying information (“PII”) documented by the A-
Numbers, but also effectively deprived the public of access to non-
exempt records in the same person-centric manner available to the
agency. In these circumstances, we approve the substitution of
neutral Unique IDs for exempt A-Numbers. Such substitution does
not alter the content of any record, but only preserves the computer
2 On the record before us, it is not clear why ICE maintains only event-
centric electronic records. ICE has long maintained person-centric paper
records, generally referred to as Alien Files, or “A-Files.” See U.S. D EP’ T OF
HOMELAND SEC., DHS/USCIS/PIA-009(a), P RIVACY IMPACT A SSESSMENT FOR
THE CENTRAL INDEX SYSTEM (CIS) 2 (2017),
https://www.dhs.gov/sites/default/files/publications/privacy-pia-uscis-09-
a-cis-april-2017.pdf (defining Alien File as “series of records . . . which
documents the history of [a particular alien’s] interaction with DHS as
required by law”); Vassilio-Diaz Decl. ¶ 12 (acknowledging that ICE
officers can view individual’s immigration history “by consulting his or her
paper ‘Alien File’”); United States v. Noria, 945 F.3d 847, 850 n.5 (5th Cir.
2019) (“The Government creates an A-file, short for Alien File, for every
non-citizen who comes into contact with a U.S. immigration agency. A-files
contain documents relating to any and all interactions which the non-
citizen has had with immigration agencies.” (internal quotation marks
omitted)); see also United States v. Sokolov, 814 F.2d 864, 874-75 (2d Cir. 1987)
(ordering production of A-file in case challenging denaturalization).

-- 5 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
6
function necessary to afford the public access to non-exempt electronic
records in the same manner that they are available to the agency.
Accordingly, we reverse the award of summary judgment to
ICE, and we remand the case for further proceedings consistent with
this opinion.
BACKGROUND
The following facts derive largely from the sworn declaration
of Donna Vassilio-Diaz, Unit Chief of the Statistical Tracking Unit
within Enforcement and Removal Operations Law Enforcement and
Systems Analysis at ICE, submitted in support of ICE’s motion for
summary judgment, as well as from matters of which the court may
take judicial notice. In FOIA cases, we accord such declarations “a
presumption of good faith,” Carney v. DOJ, 19 F.3d 807, 812 (2d Cir.
1994) (internal quotation marks omitted), and can rely on them to
support an award of summary judgment, at least to the extent “they
are not called into question by contradictory evidence in the record or
by evidence of agency bad faith,” Grand Cent. P’ship, Inc. v. Cuomo, 166
F.3d 473, 478 (2d Cir. 1999) (internal quotation marks omitted).
I. ICE Databases
Some understanding of certain ICE databases is useful to our
discussion of the issues on appeal.
ICE’s Enforcement Integrated Database (“EID”) is the agency’s
“common database repository for all records created, updated, and
accessed by a number of software applications.“ Vassilio-Diaz Decl.
¶ 6. EID allows ICE officials, along with other law-enforcement
components of the Department of Homeland Security, “to manage

-- 6 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
7
cases from the time of an alien’s arrest, in-processing, or placement
into removal proceedings, through the final case disposition.” Id.
EID, however, does not store data on a person-centric basis; rather, it
stores data in an event-centric manner. Thus, when a particular
enforcement event occurs, ICE officers enter it into EID where it is
stored with data recording similar events rather than with data
pertaining to the same alien. Nevertheless, ICE software does permit
the agency to retrieve EID data on a person-centric basis. Specifically,
with an appropriate identifier—here the alien’s A-Number—ICE can
search on an ad hoc basis for all events pertaining to that particular
alien.
Another ICE database, the Integrated Decision Support System
(“IIDS”), contains a subset of data from EID, maintained in “distinct
data sets[,] which capture populations of aliens at various points in
the removal lifecycle.” Id. ¶ 12. Thus, it too is event-centric, with data
pertaining to categories of events, e.g., removals, detentions,
administrative arrests, stored separately within IIDS. Updated
regularly, IIDS functions as a “snapshot” of EID. Id. ¶¶ 9, 11. ICE
queries IIDS to create reports for external stakeholders and to respond
to requests for information, including FOIA requests.
Alien-risk-classification-assessment data and bond data are
stored differently. The former are stored in the Risk Classification
Assessment module of ICE’s Enforcement Case Tracking System,

-- 7 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
8
which is stored in EID but not in IIDS. The latter are housed in a
separate database called the Bond Management Information System.3
II. ACLU’s FOIA Request
On October 3, 2018, ACLU submitted a FOIA request to ICE for
“electronic spreadsheet data,” i.e., “data in a spreadsheet format” for
five categories of information, each pertaining to a stage of the
deportation process: (1) initial apprehensions, (2) risk classification
assessments, (3) detentions, (4) removals, and (5) immigration bonds.
FOIA Request from David Hausman, ACLU to ICE 1 (Oct. 3, 2018)
(“ACLU FOIA Request”). ACLU’s request also denoted specific fields
of data sought for each category—e.g., “Gender,” “Birth Date,” “Entry
Date”—modeling its request in part on spreadsheet data that ICE had
produced in response to prior FOIA requests. Id. at 2.
In its request, ACLU instructed ICE that there should be “a row
in the spreadsheet for each individual or case.” Id. at 1. Further, and
as relevant here, ACLU instructed ICE that, in deleting exempt A-
Numbers from the spreadsheet, the agency should substitute
anonymized Unique IDs for each unit of observation because such a
substitution is necessary to allow ACLU to track individual (but
unidentified) aliens across the five different categories of data.4
3 Notwithstanding these differences among ICE databases, we refer to them
collectively throughout this opinion except where a particular database is
relevant to the point being discussed.
4 Toward this end, ACLU requested that each data set contain a Unique ID
field and that Unique IDs be consistent across the spreadsheets pertaining
to each category of information. It appears that federal and state

-- 8 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
9
III. District Court Proceedings
A. ACLU’s Complaint
On July 29, 2019, ACLU brought this court action charging ICE
with failing timely to search its records and to produce responsive
documents as required by FOIA. Reiterating its request for “five
categories of ‘spreadsheet data’” and again specifying the particular
data fields requested for each category, ACLU emphasized that it
largely sought “records that [ICE] ha[d] previously disclosed under
the FOIA.” Compl. ¶¶ 7-8. ACLU asserted that its FOIA request was
critical to informing the public about the government’s then-
operative immigration-enforcement policies and to understanding
changes in those policies.
government agencies frequently use Unique IDs or other anonymized
identifiers in producing records in other contexts. See, e.g., Raj Chetty et al.,
Race and Economic Opportunity in the United States: An Intergenerational
Perspective, 135 Q.J. ECON. 711, 724-25 (2020) (describing researchers’ use of
“unique person identifier . . . assigned by Census Bureau staff” to link
Census data with data from federal income tax returns otherwise “stripped
of personally identifiable information”); Judith Scott-Clayton & Basit Zafar,
Financial Aid, Debt Management, and Socioeconomic Outcomes: Post-College
Effects of Merit-Based Aid, 170 J. P UB . ECON. 68, 70 (2019) (describing how
“random scrambled identifier” in state agency data permitted that data to
be linked with data from private company and from Federal Reserve Bank
of New York); Loryana L. Vie et al., The Person-Event Data Environment:
Leveraging Big Data for Studies of Psychological Strengths in Soldiers, FRONTIERS
P SYCH ., Dec. 2013, at 2 (describing Defense Department’s Person-Event
Data Environment, which replaces social security numbers with random
strings of numbers, thereby “reduc[ing] the risk of an individual being
identified” by researchers “while maintaining enough information for
standard analysis”).

-- 9 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
10
B. ICE’s Production
On September 30, 2019, ICE responded to ACLU’s FOIA
request by producing 21 Microsoft Excel spreadsheets, containing 40
tabs of data. This equated to eight spreadsheet tabs of data for each
of the five categories of information sought, containing between 2,000
and 1,000,000 rows of data per year. ACLU viewed this production
as only partially responsive to its request because, although
spreadsheets for four of the five categories of data included a column
for “A-Numbers,” the A-Numbers themselves were redacted and
replaced, not with the requested Unique IDs, but with repeated
abbreviated citations to the two FOIA exemptions supporting
redaction, specifically, 5 U.S.C. § 552(b)(6) and § 552(b)(7)(C),5 a
substitution that did not permit person-centric tracking.
On March 30, 2020, the district court so ordered the parties’
partial stipulation of settlement. Therein, ACLU waived any
challenge to ICE’s invocation of the FOIA privacy exemptions to
withhold A-Numbers from the produced spreadsheets. At the same
time, however, the parties stipulated that on the open question of
5 These subsections exempt “personnel and medical files and similar files
the disclosure of which would constitute a clearly unwarranted invasion of
personal privacy,” 5 U.S.C. § 552(b)(6); and “records or information
compiled for law enforcement purposes” that “could reasonably be
expected to constitute an unwarranted invasion of personal privacy,” id.
§ 552(b)(7)(C).

-- 10 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
11
whether ICE was required to substitute Unique IDs for the redacted
A-Numbers, they would file cross-motions for summary judgment.6
C. Summary Judgment
In its motion for summary judgment, ICE conceded that an A-
Number is “[t]he only piece of information stored in a row of IIDS
data that connects an entry to an individual uniquely.” Vassilio-Diaz
Decl. ¶ 20. Notwithstanding, ICE submitted that, because A-
Numbers are exempt as PII, and because the substitution of such
numbers with Unique IDs would require the creation of new
records—an obligation not imposed by FOIA—ICE’s production to
ACLU without Unique IDs had satisfied its FOIA obligations.
Further, ICE professed not to have a computer program by which it
could create person-centric reports of electronic data, “i.e., with each
row corresponding to an individual and showing that individual’s
removals, detentions, etc.” Id. ¶ 12.7
In its cross-motion, ACLU submitted that its Unique ID request
effectively sought only a means to track for itself individual aliens
throughout the various events reflected in the produced
spreadsheets. ACLU characterized the connections it sought to
identify among such events as “Relational Information,” which it
6 The stipulation acknowledged that ACLU reserved the right to argue for
“alternative means for tracking persons within and across the categories of
data.” Stipulation & Order ¶ 3, ACLU Immigrants’ Rts. Project v. ICE, 2021
WL 918235 (No. 19-CV-7058), ECF No. 29.
7 At oral argument, ICE’s counsel suggested that the agency might be able
to produce such person-centric reports, a point we discuss further infra at
38-39.

-- 11 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
12
maintained was itself an agency “record” insofar as it conveyed
“information on the relationships between [event] records, which
discloses an individual’s interactions with ICE during the deportation
process.” Mem. of Law in Supp. of Pl.’s Cross-Mot. for Summ. J. at 1,
ACLU Immigrants’ Rts. Project v. ICE, 2021 WL 918235 (No. 19-CV-
7058), ECF No. 34; see also id. at 2 (arguing that “information conveyed
by a record” is itself a “record” under FOIA). ACLU also maintained
that insofar as A-Numbers convey Relational Information as well as
exempt PII, the substitution of Unique IDs for A-Numbers was
necessary here to allow the latter to be shielded without
impermissibly hiding the former. Id. at 2-3, 20-22.8
8 Before the district court, ACLU also argued that substituting Unique IDs
for A-Numbers finds support in FOIA’s requirement that agencies produce
records in “any form or format requested . . . if the record is readily
reproducible by the agency in that form or format.” Id. at 14 (emphasis
omitted) (quoting 5 U.S.C. § 552(a)(3)(B)). Although ACLU does not
specifically challenge the district court’s rejection of that argument, it does
cite § 552(a)(3)(B) in discussing the statutory scheme as a whole. See
Appellant Br. at 12-13. Moreover, one amicus argues that § 552(a)(3)(B)
supports reversal. See Br. of Amicus Curiae Electronic Frontier Foundation
at 24-26. Thus, we discuss § 552(a)(3)(B), infra at 25-30, consistent with our
obligation to consider “the broader context of the statute as a whole” when
interpreting FOIA. Seife v. FDA, 43 F.4th 231, 239 (2d Cir. 2022); see also
Kamen v. Kemper Fin. Servs., Inc., 500 U.S. 90, 99 (1991) (instructing that
“court is not limited to the particular legal theories advanced by the parties,
but rather retains the independent power to identify and apply the proper
construction of governing law”); Hankins v. Lyght, 441 F.3d 96, 104 (2d Cir.
2006) (applying Kamen to consider statutory language not relied on by party
because “[w]e are required to interpret federal statutes as they are
written”).

-- 12 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
13
On March 10, 2021, the district court granted summary
judgment in favor of ICE and denied summary judgment to ACLU.
In explaining its ruling, the district court held that replacing A-
Numbers with Unique IDs would have the agency create “new
record[s],” which FOIA did not require. ACLU Immigrants’ Rts.
Project v. ICE, 2021 WL 918235, at *5. The district court observed that
Relational Information was not itself documented in any ICE
databases or datapoints but, rather, was a “conceptual abstraction[]”
not disclosable under FOIA. Id.; see also id. at *6 (stating that “agency
is not obligated to produce information in the abstract” or to segregate
and produce “meaning of every datapoint” (internal quotation marks
omitted)).
ACLU timely appealed.
DISCUSSION
We review de novo a district court’s grant of summary judgment
in a FOIA action, “including the threshold determination of whether
the requested records are ‘agency records’ eligible for disclosure
under the statute.” Behar v. DHS, 39 F.4th 81, 88 (2d Cir. 2022). A
district court may award summary judgment on the basis of agency
declarations if the declarations “describe the justifications for
nondisclosure with reasonably specific detail, demonstrate that the
information withheld logically falls within the claimed exemption,
and are not controverted by either contrary evidence in the record or
by evidence of agency bad faith.” Knight First Amend. Inst. at Columbia
Univ. v. USCIS, 30 F.4th 318, 327 (2d Cir. 2022) (internal quotation
marks omitted). When an agency has satisfied its “burden of showing
that its search was adequate and that any withheld [records] fall

-- 13 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
14
within an exemption to the FOIA,” a plaintiff seeking to avoid an
award of summary judgment to the government must show either
bad faith sufficient to “impugn the agency’s affidavits” or “provide
some tangible evidence that an exemption claimed by the agency
should not apply or summary judgment is otherwise inappropriate.”
Carney v. DOJ, 19 F.3d at 812. In this case, the parties do not dispute
that A-Numbers are agency records, exempt from FOIA production
insofar as they convey PII. See supra at 10. The only issue in dispute
is whether ICE was required to substitute Unique IDs for deleted A-
Numbers in producing the otherwise non-exempt records responsive
to ACLU’s FOIA request.
I. The FOIA Mandate to Disclose Agency Records
A. The Original FOIA Mandate
First enacted in 1966, FOIA mandates that “each [federal]
agency, upon any request for records which (i) reasonably describes
such records and (ii) is made in accordance with published rules . . . ,
shall make the records promptly available to any person.” 5 U.S.C.
§ 552(a)(3)(A) (emphases added). As this court has long recognized,
this is “a broadly conceived statute whose overriding aim is
disclosure.” FLRA v. U.S. Dep’t of Veterans Affs., 958 F.2d 503, 505 (2d
Cir. 1992); see N.Y. Times Co. v. DOJ, 939 F.3d 479, 488 (2d Cir. 2019)
(“FOIA ‘adopts as its most basic premise a policy strongly favoring
public disclosure of information in the possession of federal
agencies.’” (quoting Halpern v. FBI, 181 F.3d 279, 286 (2d Cir. 1999))).
Nevertheless, as the highlighted text makes plain, and as the Supreme
Court has confirmed, the mandated disclosure pertains not to
information generally but, rather, to agency “records” in particular.

-- 14 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
15
Forsham v. Harris, 445 U.S. 169, 178 (1980) (stating that, although
Congress, in enacting FOIA, “undoubtedly sought to expand public
rights of access to Government information,” it “limited access to
‘agency records’” (quoting 5 U.S.C. § 552(a)(4)(B))); accord Goldgar v.
Off. of Admin., Exec. Off. of the President, 26 F.3d 32, 34 (5th Cir. 1994)
(“FOIA applies only to information in record form.”); see Yeager v.
DEA, 678 F.2d 315, 321 (D.C. Cir. 1982) (“Agencies are not . . . required
to commit to paper information that does not exist in some form as an
agency ‘record.’”).9
FOIA’s definitional section, 5 U.S.C. § 551, assigns no
specialized statutory meaning to the word “record.” Thus, we
construe the word according to its common meaning, which
references information that is written, documented, or otherwise
preserved in a tangible, perceivable, retrievable form.10 Information
9 See also Ann H. Wion, Note, The Definition of “Agency Records” Under the
Freedom of Information Act, 31 S TAN. L. R EV. 1093, 1095 (1979) (observing that
“[r]equested material does not fall within the FOIA if it is not in the form of
a ‘record’”); Stephen D. Hall, Comment, What Is a Record? Two Approaches to
the Freedom of Information Act’s Threshold Requirement, 1978 BYU L. REV. 408,
415 (stating that courts treat “term ‘record’ [as] a threshold requirement” to
FOIA production). One judge attributes the confusion that sometimes
arises in distinguishing between “information” and “records” to “the fact
that courts permit requesters to ask for general categories of information, but
agencies must release records.” Cause of Action Inst. v. DOJ, 999 F.3d 696, 705
(D.C. Cir. 2021) (Rao, J., concurring) (emphases in original).
10 See Record, BLACK ’ S LAW D ICTIONARY (11th ed. 2019) (defining “record” as
“[a] documentary account of past events, usu. designed to memorialize
those events”; “information that is inscribed on a tangible medium or that,
having been stored in an electronic or other medium, is retrievable in
perceivable form”); XIII O XFORD ENGLISH D ICTIONARY 360 (J.A. Simpson &

-- 15 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
16
that is undocumented, conceptual, or abstract is not a “record” under
FOIA. It is with this understanding of “record” that we consider
FOIA’s requirement for “full agency disclosure unless information is
exempted under clearly delineated statutory language.” Dep’t of Air
Force v. Rose, 425 U.S. 352, 360-61 (1976) (quoting S. R EP . NO . 89-813 at
3 (1965)).
There are “nine, exclusive” FOIA exemptions. American
Oversight v. DOJ, 45 F.4th 579, 587 (2d Cir. 2022); see 5 U.S.C.
§ 552(b)(1)-(9). Courts construe these exemptions narrowly, see FBI v.
Abramson, 456 U.S. 615, 630 (1982); Long v. Off. of Pers. Mgmt., 692 F.3d
185, 190 (2d Cir. 2012), and place the burden on the invoking agency
to demonstrate applicability, see Carney v. DOJ, 19 F.3d at 812.
In sum, as originally enacted, FOIA requires “virtually every
document,” i.e., record, “generated by an agency [to be made]
available to the public in one form or another,” unless an agency
clearly demonstrates that it “falls within one of the Act’s nine
exemptions.” NLRB v. Sears, Roebuck & Co., 421 U.S. 132, 136 (1975).
B. E-FOIA’s Extension of the Mandate to Electronic
Records
By the end of the Twentieth Century, Congress recognized that
“agency records” were no longer all documented on “pieces of
E.S.C. Weiner eds., 2d ed. 1989) (defining “record” as “[a]n account of some
fact or event preserved in writing or other permanent form”); WEBSTER ’ S
T HIRD NEW INTERNATIONAL D ICTIONARY 1897 (Philip Babcock Gove ed.
2002) (defining “record” as “evidence, knowledge or information
remaining in permanent form (as a relic, inscription, document)”).

-- 16 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
17
paper . . . placed in filing cabinets.” H.R. REP . NO . 104-795, at 11
(1996). A growing “volume of Federal agency records” was being
“created and retained in electronic formats.” Id. Accordingly, in 1996,
Congress enacted the Electronic Freedom of Information Act
Amendments (“E-FOIA”), Pub. L. No. 104-231, 110 Stat. 3048 (1996),
which “codified a principle already established” by federal courts, i.e.,
that “‘the full disclosure policies of the FOIA’” pertain as much to
records created or stored electronically as to those documented on
paper. Ctr. for Investigative Reporting v. DOJ, 14 F.4th 916, 938 (9th Cir.
2021) (quoting Institute for Just. v. IRS, 941 F.3d 567, 571 (9th Cir.
2019)); see S. R EP . NO. 104-272, at 29 (1996) (stating that “[a]s a general
rule, information maintained in electronic form should be no less
subject to the FOIA than information maintained in conventional
paper record form”). Toward this end, E-FOIA describes a disclosable
agency “record” as “any information that would be an agency record
subject to the requirements of [5 U.S.C. § 552] when maintained by an
agency in any format, including an electronic format.” 5 U.S.C.
§ 552(f)(2)(A).11 Thus, E-FOIA makes plain that the threshold
“record” requirement for FOIA, as well as that Act’s full-disclosure,
11 As the D.C. Circuit has observed, this language does “not broaden the
concept of an agency record”; it merely clarifies that, under FOIA, a
“record” includes documented information in all formats. Aguiar v. DEA,
992 F.3d 1108, 1111 (D.C. Cir. 2021) (quoting H.R. R EP. NO. 104-795, at 19-
20). That observation finds support in the legislative history. See, e.g., H.R.
R EP. NO. 104-795, at 19 (stating that “matter not previously subject to FOIA
when maintained in a non-electronic format is not made subject to FOIA by
this bill”).

-- 17 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
18
narrow-exemption philosophy, applies equally in the electronic and
in the physical contexts.12
As relevant here, E-FOIA further updates FOIA by adding
provisions requiring federal agencies (1) to provide a responsive
“record in any form or format requested by the person if the record is
readily reproducible by the agency in that form or format,” id.
§ 552(a)(3)(B); and (2) to make “reasonable efforts to search for the
records in electronic form or format”—defining “search” as “to
review, manually or by automated means, agency records for the
purpose of locating those records which are responsive to a request,”
id. § 552(a)(3)(C)-(D). In imposing this search requirement, Congress
specifically recognized that “[c]omputer records found in a database
rather than in a file cabinet may require the application of codes or
some form of programming to retrieve the information.” H.R. R EP .
NO . 104-795, at 22. The need to employ such codes or programming
would “not amount to the creation of records.” Id.; see Ctr. for
Investigative Reporting v. DOJ, 14 F.4th at 938 (holding that “using a
query to search for and extract a particular arrangement or subset of
data already maintained in an agency’s database does not amount to
the creation of a new record”). At the same time, however, E-FOIA,
like FOIA, requires agencies to disclose only existing records, “not [to]
create documents that do not exist.” H.R. R EP . NO . 104-795, at 22.
Thus, agencies and courts are left to the not-always-easy task of
identifying “when the manipulation of data points in an electronic
12 See generally H.R. R EP. NO. 104-795, at 20 (stating that, after E-FOIA, as
before, it is “information that passes the threshold test of being an agency
record” that is subject to disclosure “[n]o matter how it is preserved”
(emphasis added)).

-- 18 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
19
database . . . crosses the all-important line between searching a
database, on the one hand, and either creating a record or conducting
research in a database on the other.” National Sec. Couns. v. CIA, 898
F. Supp. 2d 233, 270-71 (D.D.C. 2012).
C. FOIA’s Segregability Requirement
FOIA’s segregability requirement can sometimes inform that
inquiry. It instructs that “[a]ny reasonably segregable portion of a
record shall be provided to any person requesting such record after
deletion of the portions which are exempt.” 5 U.S.C. § 552(b). Thus,
agencies responding to FOIA requests must “differentiate among the
contents of a document rather than . . . treat it as an indivisible
‘record,’” FBI v. Abramson, 456 U.S. at 626, disclosing “non-exempt
portions . . . unless they are inextricably intertwined with exempt
portions,” Mead Data Cent., Inc. v. U.S. Dep’t of Air Force, 566 F.2d 242,
260 (D.C. Cir. 1977); see U.S. Dep’t of State v. Ray, 502 U.S. 164, 173
(1991) (observing that agency has burden of demonstrating inability
to segregate).
Congress reinforced the segregability obligation in 2016 when,
“concern[ed] that ‘some agencies [were] overusing FOIA
exemptions,’” Seife v. FDA, 43 F.4th 231, 235 (2d Cir. 2022) (second
alteration in original) (quoting S. R EP . NO . 114-4, at 2 (2015)), it enacted
the FOIA Improvement Act of 2016, Pub. L. No. 114-185, 130 Stat. 538,
one provision of which specifically requires agencies to “consider
whether partial disclosure of information is possible whenever the
agency determines that a full disclosure of a requested record is not
possible” and to “take reasonable steps necessary to segregate and
release nonexempt information,” 5 U.S.C. § 552(a)(8)(A)(ii).

-- 19 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
20
With these principles in mind, we consider the challenged
award of summary judgment to ICE.
II. “Relational Information”
We begin by briefly addressing ACLU’s primary argument for
urging error in the district court’s finding that the substitution of
Unique IDs for A-Numbers requires the creation of new records.
ACLU submits that the substitution reveals “Relational
Information”—i.e., “information on the relationships between
records, which disclose an individual’s interactions with ICE during
the deportation process”—which is not a new record but, rather, a
non-exempt record already existing in ICE databases. Mem. of Law
in Supp. of Pl.’s Cross-Mot. for Summ. J. at 1. Alternatively, ACLU
maintains that Relational Information is a segregable, non-exempt
component of A-Numbers, which ICE does not dispute are pre-
existing records. These arguments present certain challenges,13 which
we need not resolve conclusively because, in the end, we conclude
that ICE was not entitled to summary judgment.
In reaching that conclusion, we note that ACLU did not identify
“Relational Information” as the records being sought in either its
FOIA request to ICE or in its initial filings with the district court.
Rather, ACLU identified the requested records as “electronic
spreadsheet data,” i.e., datapoints existing within ICE’s databases
13 For example, a particular database query can identify, and in that same
sense link, responsive existing datapoints. That may demonstrate a
relationship among these datapoints. But is that relationship documented
in the database separate and apart from the responsive datapoints? The
question admits no easy answer.

-- 20 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
21
produced in a spreadsheet format. See ACLU FOIA Request, at 1.14
The identification of existing datapoints as records disclosable under
FOIA finds support in caselaw and is not here disputed by ICE. See,
e.g., Institute for Just. v. IRS, 941 F.3d at 570 (“In the context of a request
for a database, FOIA requires agencies to disclose all [existing] non-
exempt data points.” (internal quotation marks omitted)).
Focusing on these existing datapoints, we conclude that, in the
circumstances of this case, A-Numbers are simply a tool—a sort of
key or code—chosen by ICE to access its event-centric databases in
such a way as to obtain existing datapoints. To the extent A-Numbers
are themselves FOIA-exempt records, ACLU argues for their
replacement by Unique IDs—numbers meaningless in themselves but
able to perform the same access function as A-Numbers—a process
that would neither document any new information nor create any
new records in ICE databases. That argument persuades without
regard to whether the relationship among such datapoints is a
“record” under FOIA for reasons we now explain.
III. ICE Must Produce the Responsive Datapoints in a Person-
Centric Arrangement or Provide ACLU with a Means to
Do So Itself
14 Even though ACLU instructed ICE to substitute Unique IDs for exempt
A-Numbers in the requested spreadsheets, it appears to have recognized
that it was the datapoints reported in the spreadsheets, not the links that
could be identified by means of the Unique IDs, that were the disclosable
FOIA records. See, e.g., Hausman Decl. ¶¶ 3, 6-7, 13 (identifying sought
“records” as datapoints drawn from ICE databases, and explaining that
Unique IDs were sought to “link the[se] records”).

-- 21 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
22
From the outset, ACLU has made clear that what it seeks are
requested fields of data in a spreadsheet format that allows it to track
datapoints pertaining to individual, unidentified aliens. ICE
acknowledges that it can, and on an ad hoc basis does, itself retrieve
datapoints pertaining to individual aliens from across its event-
centric databases using A-Numbers. Thus, the question we consider
is whether under FOIA, ICE’s acknowledged ability to access
immigration records in a person-centric manner—in other words, its
own ability to track a single individual across the various stages of
immigration proceedings—requires ICE to afford the public (here,
ACLU) similar access to the data.
In urging a negative answer, ICE relies essentially on (1) the
exempt status of A-Numbers; and (2) FOIA’s requirement that
agencies produce existing records, not that they create new ones. We
consider these arguments mindful that FOIA’s exemptions must be
construed narrowly, see FBI v. Abramson, 456 U.S. at 630, and that even
when exemptions shield records, agencies must take “reasonable
steps” to ensure the release of all non-exempt information in any
readily reproducible requested form or format, 5 U.S.C. § 552(a)(3)(B),
(a)(8)(A)(ii). When we do that in the particular circumstances here,
text, context, and history lead us to reject ICE’s arguments.
A. Construing Exemptions Narrowly
Applying these principles here, we note ICE’s
acknowledgment that, at present, exempt A-Numbers are the only
datapoints within its databases “that connect[] an entry uniquely to
an individual.” Appellee Br. at 6. Thus, ICE concedes that
“[w]ithout . . . A-numbers, the ACLU cannot use ICE’s data to track

-- 22 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
23
individuals between the separate IIDS datasets.” Mem. of Law in
Supp. of Def.’s Mot. for Summ. J. at 13, ACLU Immigrants’ Rts. Project
v. ICE, 2021 WL 918235 (No. 19-CV-7058), ECF No. 31.15 We are
further mindful, however, that A-Numbers are not essential to
perform this function; other numbers, letters, symbols, or
combinations thereof could be substituted to the same effect. In these
circumstances—i.e., where ICE has chosen to make exempt A-
Numbers the essential code for gaining person-centric access to
datapoints in its event-centric databases, and where ICE itself uses
that key or code to gain such access—we conclude that ICE may not
rely on A-Numbers’ exemption from FOIA disclosure to deny the
public equal access to non-exempt records. Rather, ICE must find an
alternative means to provide ACLU with responsive person-centric
access to non-exempt records.
Indeed, to hold otherwise could have the perverse effect of
encouraging agencies to make exempt records the singular means for
gaining access to non-exempt records responsive to a particular query
15 It is not clear from the record whether (1) ICE can use A-Numbers to
search for data across all its databases or only in IIDS or in EID, see Oral
Arg. at 33:57-34:30, 35:08-35:20; and (2) such a search is sufficient, in any
event, to respond to ACLU’s FOIA request. To the extent relevant, these
matters can be pursued further on remand. Nevertheless, we make two
observations. First, as the D.C. Circuit has stated, while “[t]here is no
[FOIA] requirement that an agency search every record system . . . [,] the
agency cannot limit its search to only one record system if there are others
that are likely to turn up the information requested.” Oglesby v. U.S. Dep’t
of Army, 920 F.2d 57, 68 (D.C. Cir. 1990). Second, FOIA itself does not
require an agency to search for responsive records “when such efforts
would significantly interfere with the operation of the agency’s automated
information system.” 5 U.S.C. § 552(a)(3)(C).

-- 23 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
24
and, thereby, effectively to conceal those records from the public, at
least in the way responsive to the query.16 Such an outcome is
contrary to the “clear legislative intent” underlying FOIA: “to assure
public access to all governmental records whose disclosure would not
significantly harm specific governmental interests.” Dep’t of Air Force
v. Rose, 425 U.S. at 365 (internal quotation marks omitted).
Here, ACLU’s proposed substitution of Unique IDs for A-
Numbers is a reasonable step for affording the public the same
person-centric access to non-exempt records that is available to ICE.
In reaching that conclusion, we act in furtherance of our obligation
“narrowly” to construe FOIA’s exemptions. FBI v. Abramson, 456 U.S.
at 630. In doing so here, we distinguish between the content of an
electronic record and the function it may have been assigned within a
computer system. The relevant FOIA exemptions, 5 U.S.C.
§ 552(b)(6)-(7), protect against “unwarranted invasion[s] of personal
privacy.” These exemptions support ICE withholding A-Numbers
from the public because their content is effectively all PII. But the
same conclusion does not obtain with respect to the function that ICE
has assigned A-Numbers within its electronic databases, which is to
afford person-centric access to non-exempt records across ICE’s
event-centric databases. As already noted, it was not necessary for
ICE to use an exempt record to perform this function. Any
combinations of numbers, letters, or symbols would do.
Moreover, precisely because Unique IDs can be meaningless in
themselves, they do not alter the content of any exempt record. Nor
16 We do not suggest that such is ICE’s intent here.

-- 24 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
25
do they document any new information, or otherwise create any new
records. Rather, Unique IDs serve only to substitute for deleted
exempt A-Numbers in order to preserve a function necessary to
afford the public the same person-centric access to non-exempt
records that ICE already has. In these circumstances, the substitution
of Unique IDs for A-Numbers is a reasonable step in shielding the
exempt PII content of A-Numbers, while preserving the access
function formerly performed by those exempt records.
A physical analogy may be useful. If an agency were to
maintain non-exempt, person-centric records in a vault, the lock of
which could be opened only with a combination of exempt numbers,
the agency could not decline to produce documents from the vault by
invoking the exemption afforded to the lock combination. Rather,
FOIA would oblige the agency to open the vault itself and produce
the responsive records. Or, the agency would have to change the
combination to non-exempt numbers and thereby afford public
access. So here, ICE must itself use A-Numbers to produce a
spreadsheet of person-centric data for ACLU, see infra at 38-39, or, as
ACLU here requests, ICE must change the “lock” combination
numbers so that ACLU can itself access records in a person-centric
manner.
B. E-FOIA’s “Form or Format” Requirement
This conclusion not only comports with the strict application of
FOIA exemptions, but also finds some support in the statutory
provision requiring agencies to provide their non-exempt records to
the public in “any form or format . . . readily reproducible.” 5 U.S.C.
§ 552(a)(3)(B). Here, we conclude that ICE’s substitution of Unique

-- 25 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
26
IDs for A-Numbers would effectively allow it to provide non-exempt
records in the requested person-centric form or format. In concluding
otherwise, the district court relied on Sai v. TSA, 466 F. Supp. 3d 35
(D.D.C. 2020), which narrowly construed “form” as used in 5 U.S.C.
§ 552(a)(3)(B) to refer only to “the media—e.g., paper or thumb drive”
in which a record might be produced, and “format” to refer only “to
the electronic ‘structure for the processing, storage, or display’ of
data . . . —e.g., PDF or JPEG.” Id. at 47-48 (quoting Format, CONCISE
O XFORD ENGLISH D ICTIONARY (Oxford University Press, 12th ed.
2011)); accord ACLU Immigrants’ Rts. Project v. ICE, 2021 WL 918235, at
*6.
Such a construction does not comport with our own
understanding of the ordinary meaning of “form” and “format.”
Dictionary definitions of these words indicate that records might be
supplied in whatever “pattern or schema,” W EBSTER’S THIRD NEW
INTERNATIONAL D ICTIONARY , supra note 10, at 892 (defining “form”);
“general plan of physical organization or arrangement,” id. at 893
(defining “format”); or “style or manner of arrangement or
presentation,” VI OXFORD E NGLISH D ICTIONARY , supra note 10, at 85
(defining “format”), requested.17
17 We are unpersuaded by Sai v. TSA’s reliance on a computer-centric
definition of “format” to limit that word to file type, as it is uncontested that
the word “format” as used in § 552(a)(3)(B) applies to a paper record too.
Insofar as Sai v. TSA—not the dictionary it cites—interprets “structure for
the processing, storage, or display” to mean file type, that interpretation is
not obvious, particularly in light of other definitions in the computer
context that define format more expansively to reference the way data is
“arranged.” See VI OXFORD ENGLISH D ICTIONARY, supra note 10, at 85

-- 26 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
27
Context also cautions against a narrow construction of
“format.” In another § 552 E-FOIA provision, Congress states that the
law’s disclosure obligation reaches “any information that would be
an agency record . . . in any format, including an electronic format.”
Id. § 552(f)(2)(A) (emphasis added). Sai v. TSA does not dispute that
this reference to an “electronic format” is not singular. See 466 F.
Supp. 3d at 45; United States v. Edwards, 834 F.3d 180, 193 (2d Cir. 2016)
(stating that use of indefinite article “implies the possibility of a larger
number than one”). More to the point, the statutory use of the word
“any” has long signaled “Congress’s intent to sweep broadly to reach
all varieties of the item referenced.” Cohen v. JP Morgan Chase & Co.,
498 F.3d 111, 117 (2d Cir. 2007) (emphasis added); see Republic of Iraq
v. Beaty, 556 U.S. 848, 856 (2009) (“[T]he word ‘any’ . . . has an
expansive meaning, giving us no warrant to limit the class of [things
referenced].” (some internal quotation marks and citation omitted)).
Additionally, although E-FOIA’s legislative history sometimes
references different media when discussing “form,” see, e.g., H.R. REP .
NO . 104-795, at 20 (stating that “information should be made available
in another electronic form, e.g., CD-ROM or disc”), it elsewhere
emphasizes that the purpose of the “form or format” provision is to
“provide public access to information in more meaningful formats”
so that information can be more “useable,” Federal Information Policy
(defining “format” in the context of “Computers,” as “[a] particular
arrangement of data or characters in a record, instruction, word, etc., in a
form that can be processed or stored by a computer”); Format, AMERICAN
HERITAGE D ICTIONARY, https://www.ahdictionary.com/word/search.
html?q=format (last viewed Dec. 7, 2022) (defining “format” in the context
of “Computers” as “[t]he arrangement of data for storage or display”).

-- 27 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
28
Oversight: Hearing Before the Subcomm. on Gov’t Mgmt., Info. & Tech. of
the H. Comm. on Gov’t Reform & Oversight, 104th Cong. 12 (1996)
(statement of Sen. Patrick Leahy18). This suggests a certain flexibility
in the format requirement. Still elsewhere, and as pertinent here, the
history instructs that “agencies should search for and retrieve data in
the same manner used in the ordinary course of agency business with
their existing retrieval-programming capability,” and should even
“comply with . . . requests” to “have data retrieved according to
specifications other than those ordinarily used.” S. R EP . NO . 104-272,
at 28.
We do not here attempt to delineate the outer boundaries of
FOIA’s “form or format” requirement, although we note that the
statute itself conditions production on the records being “readily
reproducible” by the agency in the requested form or format. 5 U.S.C.
§ 552(a)(3)(B). We conclude only that text, context, and history
support a more liberal construction of the provision than the district
court here recognized.
Like the D.C. Circuit, however, we are mindful that identifying
readily reproducible forms or formats presents particular challenges
in the electronic context given constantly “evolving practices of data
storage and use.” Aguiar v. DEA, 992 F.3d 1108, 1112 (D.C. Cir. 2021).
For this reason, in Aguiar itself, the court left open the question
18 Senator Leahy was E-FOIA’s leading sponsor. See S.1090 - Electronic
Freedom of Information Improvement Act of 1996, C ONGRESS.GOV,
https://www.congress.gov/bill/104th-congress/senate-bill/1090 (last
viewed Dec. 7, 2022).

-- 28 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
29
“whether and under what circumstances a duty of production would
arise under FOIA when an agency technically stores information in
one way, such as numerically as GPS coordinates, but typically
accesses that information in another way, such as graphically as
maps.” Id. We cannot avoid that question here because although ICE
stores immigration data by event, it can, and on an ad hoc basis does,
access that information in a person-centric manner in the regular
course of agency business.19
E-FOIA’s legislative history suggests that Congress anticipated
that agencies might store electronic records in ways different from
how the public might request them. In such circumstances Congress,
nevertheless, expected agencies to take reasonable steps to effect
retrieval in the requested form or format, even if that required some
conversion of data. Senator Patrick Leahy made this point when he
stated:
If an agency maintains an electronic information system
in such a way that objectively understandable access to
any nonexempt information in it is dependent upon a
computer program or software that is unavailable to the
public, then the agency must upon request, . . . take all
19 Aguiar v. DEA is distinguishable from this case because (1) ICE itself uses
the A-Numbers to serve the function of accessing records in a person-
centric manner, and (2) the Unique IDs do not document any new
information. In Aguiar, not only did the agency not itself view data in the
particular graphical arrangement plaintiff requested, it also did not possess
the software required to access the data in the form requested. See 992 F.3d
at 1113. Moreover, supplying the requested graphical arrangement would
have required “editorial judgment” on the agency’s part, id., a requirement
absent here given the meaninglessness of Unique IDs, see infra at 35 & n.21.

-- 29 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
30
reasonable steps to convert the data in order to afford
FOIA access to it in a requested electronic form.
S. R EP . NO. 104-272, at 32. Here, person-centric access to non-exempt
records in ICE databases is “dependent upon” A-Numbers, records
that because of their PII content are “unavailable to the public.” One
way of “convert[ing]” exempt A-Numbers to afford the public the
same person-centric access to non-exempt records as is available to
ICE could be to produce all responsive datapoints from its event-
centric databases but to substitute Unique IDs for exempt A-
Numbers, as ACLU requests. This would allow ACLU to arrange the
non-exempt records for itself in a person-centric manner or “format.”
In approving this course, we are mindful that Congress foresaw
the need for an agency to apply “codes or some form of
programming” to retrieve records in a requested electronic format,
and expressly stated that the use of such codes or programming
would “not amount to the creation of records.” H.R. R EP . NO . 104-
795, at 22. That conclusion applies as much to substituted access code
numbers—here, Unique IDs in place of exempt A-Numbers—as it
does to the application of new computer coding or programming to
retrieve responsive records. Though the tools are different, each
functions to retrieve non-exempt records in their existing state but
organized in a particular format. Thus, in the urged substitution, ICE
would query databases for datapoints by reference to meaningless
Unique IDs rather than exempt A-Numbers. Like the D.C. Circuit, we
are satisfied that “using a query to search for and extract a particular
arrangement or subset of data already maintained in an agency’s
database does not amount to the creation of a new record.” Ctr. for
Investigative Reporting v. DOJ, 14 F.4th at 938.

-- 30 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
31
C. FOIA’s Segregation and Redaction Principles
The approved substitution also finds support in principles
applicable to FOIA’s segregation and redaction provisions, which
expect an agency to produce the segregable, non-exempt information
in a record after “deleti[ng]” exempt information. 5 U.S.C. § 552(b).
In the physical context, deletion is frequently accomplished by cutting
or blacking out exempt text from paper records. But such techniques
do not always transfer to more complex electronic formats. Thus,
some courts have approved the use of unique identifiers or other
anonymization techniques to segregate exempt from non-exempt
information within an electronic record.20 We need not here decide
20 See, e.g., Evans v. BOP, 951 F.3d 578, 587 (D.C. Cir. 2020) (remanding for
consideration, inter alia, of whether faces in prison video could be blurred
or replaced in such a way as to allow parties to see when relevant actions
were taken by persons in guard uniforms versus persons in prison garb);
Hawkinson v. ICE, 554 F. Supp. 3d 253, 275 (D. Mass. 2021) (stating that
substitution of “unique identifier” was “arguably . . . a method of
redaction” that may be required in some circumstances); Mattachine Soc’y of
Wash., D.C. v. DOJ, 267 F. Supp. 3d 218, 228 (D.D.C. 2017) (holding that
substitution of alphanumeric markers for names throughout documents
“protect[ed] . . . privacy interests” while “allowing the public to better study
the effects” of particular executive order); City of Chicago v. ATF, No. 00-CV-
3417, 2001 WL 34088619, at *4-5 (N.D. Ill. Mar. 8, 2001) (stating that “unique
identifier code would serve to separate the sensitive information”
identifying persons and gun serial numbers from relevant “information
regarding trafficking patterns”), rev’d on other grounds, 423 F.3d 777 (7th Cir.
2005); ACLU of S. Cal. v. Super. Ct., 400 P.3d 432, 440-41 (Cal. 2017)
(remanding for trial court to consider under California FOIA feasibility of
different methods for anonymizing data, including “substitution” of
“unique (fictional) number[s]” for exempt datapoints); Bowie v. Evanston
Cmty. Consol. Sch. Dist. No. 65, 538 N.E.2d 557, 560-61 (Ill. 1989) (holding,
under Illinois FOIA, that to protect privacy while disclosing requested

-- 31 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
32
that such substitution should be approved in all circumstances. We
conclude only that Unique IDs are apt here where they do not
substitute for any content in an exempt document. Indeed, in
responding to ACLU’s FOIA request, ICE can withhold exempt A-
Numbers in their entirety. The substitution of Unique IDs for
redacted A-Numbers here serves only to maintain a function within
ICE databases without which the public cannot access non-exempt
records in the same manner as the agency does.
This does not run afoul of the D.C. Circuit’s reasoning in Yeager
v. DEA, relied on by ICE. There, the court declined to order DEA to
alter the content of an agency record “in such a way that [the record]
no longer falls within a specific [FOIA] exemption.” 678 F.2d at 322.
The court reasoned that, in enacting FOIA, Congress did not intend
“any manipulation or restructuring of the substantive content of a
record when it commanded agencies to ‘delete’ exempt information.”
Id. at 323 (emphasis added). Rather, it was the “deletion of (exempt)
information” from an agency record that would “provide full
protection for the purposes to be served by the exemption.” Id.
(internal quotation marks omitted).
records, defendant was required to “produce a masked and scrambled
record,” which did “not lead to the creation of a ‘new’ record”); Kryston v.
Bd. of Educ., 77 A.D.2d 896, 897, 430 N.Y.S.2d 688, 690 (2d Dep’t 1980)
(holding, under New York FOIA, that “rearranging or ‘scrambling’”
records does not constitute record creation and would simultaneously
protect privacy, provide requested records, and impose no onerous burden
on agency). But see, e.g., Institute for Just. v. IRS, 547 F. Supp. 3d 1, 8 n.3
(D.D.C. 2021) (stating that, on remand, agency is not required to create
“anonymous identifiers” for the officers or agents listed in records because
FOIA does not obligate creation of records).

-- 32 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
33
We note that Yeager predates E-FOIA, and thus its
pronouncements were made without the benefit of Congress’s views
on the particular efforts that agencies might reasonably be expected
to take in retrieving requested electronic records. See supra at 16-19
(quoting H.R. R EP . NO . 104-795, at 22; S. R EP . NO. 104-272, at 31). In
any event, this case is distinguishable from Yeager. There, the
proposed replacement of the specific place and date of certain events
with general references to geographic region and span of years would
undoubtedly have altered the “substantive content” of the produced
record. Yeager v. DEA, 678 F.2d at 319 n.9, 323. By contrast, the
substitution of Unique IDs here would make no changes to the
substantive content of exempt A-Numbers. Nor would it permit A-
Numbers to be produced in some altered state. Rather, Unique IDs
would replace A-Numbers in their entirety for the sole purpose of
preserving the access function A-Numbers perform within ICE’s
computer system.
The particular Unique IDs substituted for this purpose would
be no more relevant to the performance of that function than the
particular A-Numbers had been. All that matters is that there be some
number, letter, or symbol that can be tracked across ICE databases to
retrieve existing, non-exempt datapoint records pertaining to
individual aliens. Absent preservation of this function, the exemption
afforded A-Numbers effectively becomes a lock that, in violation of
FOIA, denies the public access to non-exempt records in the same
manner that the records are available to the agency.
We have already discussed those parts of E-FOIA’s legislative
history indicating that Congress did not view an agency’s use or

-- 33 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
34
creation of new codes or queries to access electronic records
responsive to a FOIA request as the creation of a new record. See supra
at 29-30. In urging otherwise, ICE cites this court’s decision in ACLU
v. DOJ, 681 F.3d 61 (2d Cir. 2012). In that case, we ruled that a district
court had exceeded its authority under FOIA by proposing a
disclosure “compromise,” whereby classified information in
responsive records would be replaced by “a purportedly neutral
phrase composed by the court.” Id. at 71. We stated that a court
cannot order “an agency to produce anything other than responsive,
non-exempt records,” and that requiring an agency to “alter[] or
modif[y]” existing records “would effectively be ‘creating’
documents—something FOIA does not obligate agencies to do.” Id.
ICE submits that this reasoning tracks that of other courts of appeals
and warrants affirming the award of summary judgment in its favor.
See Flightsafety Servs. Corp. v. DOL, 326 F.3d 607, 613 (5th Cir. 2003)
(holding that requiring agency to “insert new information in place of
the redacted information requires the creation of new agency records,
a task that the FOIA does not require the government to perform”);
Students Against Genocide v. Dep’t of State, 257 F.3d 828, 837 (D.C. Cir.
2001) (rejecting request that agency “produce new photographs at
different resolution” to mask confidential information, stating that
“although agencies are required to provide ‘any reasonably
segregable,’ non-exempt portion of an existing record, 5 U.S.C.
§ 552(b), they are not required to create new documents”). We
disagree.
Neither ACLU v. DOJ nor any of the other cases cited by ICE
are akin to this one. In ACLU v. DOJ, the proposed substitution not
only would have altered the “substantive content” of the exempt

-- 34 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
35
record—a concern highlighted in Yeager v. DEA, 678 F.3d at 323,
discussed supra at 32-33—but also would have required the exercise
of judgment and analysis in effecting the proposed substitution. By
contrast, the substitution here would have no effect on the substantive
content of A-Numbers. See supra at 24-25. Substitution would simply
preserve the function that such numbers performed in identifying
responsive, non-exempt records within ICE databases. Further, we
understand that the substitution of meaningless Unique IDs could be
effected by an automated replacement program without any agency
(or court) analysis, research, or judgment.21 As for what
programming steps an agency must take to identify and retrieve non-
exempt records, ACLU v. DOJ had no occasion to consider that
question, much less to consider it in circumstances where, as here, the
agency made its ability to identify and retrieve responsive non-
exempt records dependent on an exempt record. In sum, because the
circumstances and issues for decision in this case differ significantly
21 In ACLU v. DOJ, we expressed particular concern that it was the district
court, rather than the agency, exercising judgment about redactions and
substitutions for classified material. See 681 F.3d at 71-72. In Everytown for
Gun Safety Support Fund v. ATF, 403 F. Supp. 3d 343 (S.D.N.Y. 2019), rev’d
and remanded on other grounds, 984 F.3d 30 (2d Cir. 2020), the district court
suggested that where generating responsive information requires even the
agency “to engage in additional research or conduct additional analyses
above and beyond the contents of its database,” there was the possibility of
new record creation, id. at 359. We need not here decide whether to adopt
this Everytown test. It suffices to note that the proposed substitution in this
case raises none of the Everytown concerns.

-- 35 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
36
from those in ACLU v. DOJ, we do not think that the holding in that
case precludes the proposed substitution here.
D. The Burden of Substitution
Finally, we consider whether the substitution of Unique IDs for
A-Numbers is a reasonable or unduly burdensome means for
producing the requested non-exempt records. See generally 5 U.S.C.
§ 552(a)(8)(A)(ii)(II) (referencing segregation). As noted supra at 18,
FOIA expressly requires an agency to make “reasonable efforts to
search for . . . records in electronic form or format.” Id. § 552(a)(3)(C).
And Congress, in imposing this search requirement, recognized that
“[c]omputer records found in a database rather than in a file cabinet
may require the application of codes or some form of programming”
for their retrieval. H.R. R EP . NO. 104-795, at 22.
Nevertheless, the “time and resources” that an agency must
commit to retrieve electronic records may be pertinent to identifying
the efforts that can reasonably be expected to retrieve responsive
agency records. Cook v. Nat’l Archives & Recs. Admin., 758 F.3d 168,
178 (2d Cir. 2014) (internal quotation marks omitted). The “value” of
what can be retrieved can also inform the inquiry. Mays v. DEA, 234
F.3d 1324, 1327 (D.C. Cir. 2000) (explaining “excision of exempt
information” not required where it “would impose significant costs
on the agency and produce an edited document with little
informational value” (internal quotation marks omitted)).
Focusing first on value, ICE itself acknowledges that, without
exempt A-Numbers, it is impossible to access any non-exempt records
in the same person-centric manner that ICE can. Thus, to the extent

-- 36 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
37
the proposed substitution is necessary to afford such comparable
access, it yields high informational value.
As for the burden imposed, the few courts to have considered
the question have concluded that it is not unduly burdensome to
require agencies already possessing computer capabilities to acquire
software or to craft new computer queries to be able to retrieve
responsive electronic records from their databases. See Stahl v. DOJ,
No. 19-CV-4142, 2021 WL 1163154, at *7 (E.D.N.Y. Mar. 26, 2021)
(observing that if agency could avoid production of responsive video
recording by arguing that it would need to acquire video-editing
software, “no video would ever be disclosed”); City of Chicago v. ATF,
2001 WL 34088619, at * 5 (deeming few hours required to write
computer program to retrieve encrypted data to be “minuscule”
burden); see also S. R EP . NO . 104-272, at 28 (“When requesters seek to
have data retrieved according to specifications other than those
ordinarily used by agencies for data retrieval from the database
system involved, agencies should comply with such requests where
they can reasonably and efficiently do so.”). We assume that this
conclusion may vary depending on circumstances.
We need not pursue the matter further here, however, because
ICE has conceded that “the burden” involved in substituting Unique
IDs for A-Numbers “would not meet the threshold applied to the
burden for segregability.” Appellee Br. at 13 n.2.22 Insofar as any
22 While ICE here spoke of “segregability,” we think it used the term, even
if not aptly, to reference the substitution being sought here by ACLU. See
App’x 129 (stating before district court that ICE was not arguing that
burden of substituting Unique IDs for A-Numbers would exceed

-- 37 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
38
questions may remain as to ICE’s technical capability to substitute
Unique IDs for A-Numbers consistently across all five databases, we
leave those to be addressed by the district court on remand consistent
with this opinion and after any further inquiry into the nature of ICE
databases that may be warranted.
E. The “Big Spreadsheet” Alternative
One final observation. Although the issue on summary
judgment (and, thus, on appeal) was limited to whether FOIA
requires ICE to substitute Unique IDs for A-Numbers, lingering in the
record is the unanswered question of whether ICE might also
satisfactorily respond to ACLU’s FOIA request by producing a “Big
Spreadsheet,” each line of which contains all datapoints retrieved
from across ICE databases pertaining to a single (unidentified) alien.23
At oral argument before this court, ICE suggested that the Big
Spreadsheet option was an alternative means to provide ACLU with
a person-centric view of the responsive records without entailing
record creation. See Oral Arg. at 22:07-22:38. Meanwhile, both in its
brief to this court and at oral argument, ACLU not only stated that
ICE could avoid the substitution of Unique IDs for A-Numbers by
“reasonability standards . . . provided for segregation or the readily
reproducible standard that is required under the form or format requirement”
(emphasis added)).
As noted supra note 4, the substitution of Unique IDs in such circumstances
is no novel practice; federal agencies appear frequently to employ it in
affording public access to their records.
23 Each line in the spreadsheet would essentially mirror the data ICE
retrieves when it uses A-Numbers to conduct a person-centric search of its
databases, but with the A-Numbers deleted.

-- 38 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
39
producing a “Big Spreadsheet,” but also indicated that such
production “would [be] a sufficient response to the ACLU’s request.”
Appellant Br. at 7 & n.4; Oral Arg. at 41:45-42:45. We do not ourselves
reach any conclusions regarding a “Big Spreadsheet” response to
ACLU’s FOIA request.24 We state only that nothing in this opinion
should be understood to foreclose further consideration of this
alternative on remand.25
CONCLUSION
To summarize, in the particular circumstances of this case
where,
(1) ICE has chosen to make exempt records, i.e., A-Numbers,
the sole key or code for accessing non-exempt records
pertaining to individual aliens;
(2) ICE can, and does, itself use exempt A-Numbers for this
purpose;
(3) the agency’s assignment of that access function to an
exempt record effectively denies public access to non-
24 While we note that some district courts have held that requiring ICE to
produce a person-centric report akin to the “Big Spreadsheet” proposed
here would itself entail record creation, see Long v. ICE, No. 17-CV-506, 2022
WL 705493, at *4-6 (N.D.N.Y. Mar. 9, 2022); Long v. ICE, No. 17-CV-1097,
2021 WL 3931879, at *4-5 (D.D.C. Sept. 2, 2021), we express no view on the
merits of these rulings.
25 ACLU states that it requested the substitution of Unique IDs as a
comparatively less burdensome means of disclosure than producing a Big
Spreadsheet. ICE, which can be expected to have a better understanding of
its own computer systems, can state its position on this point in the district
court as circumstances warrant.

-- 39 of 40 --

21-1233
ACLU Immigrants’ Rts. Project v. ICE
40
exempt records in the same form and format available to
the agency;
(4) the content of the exempt record is irrelevant to its
assigned function; any combinations of numbers, letters,
or symbols—meaningless in themselves—could perform
the function; and
(5) such a substitution would not alter the substantive
content of exempt A-Numbers but would only preserve
an access function across ICE’s event-centric databases,
we conclude that the substitution of Unique IDs for A-Numbers does
not create any new agency records and is a reasonable step to shield
the exempt content of A-Numbers while preserving the function
necessary to afford public access to non-exempt records in the same
person-centric form or format available to the agency.
Accordingly, we R EVERSE the award of summary judgment to
ICE, and we R EMAND the case to the district court for further
proceedings consistent with this opinion.

-- 40 of 40 --