                     FOR PUBLICATION

   UNITED STATES COURT OF APPEALS
        FOR THE NINTH CIRCUIT


 GREGORIO PEREZ CRUZ,                              No. 15-70530
                                Petitioner,
                                                   Agency No.
                     v.                           A095-748-837

 WILLIAM P. BARR, Attorney General,
                        Respondent.                  OPINION

          On Petition for Review of an Order of the
              Board of Immigration Appeals

          Argued and Submitted September 5, 2018
                 San Francisco, California

                       Filed June 13, 2019

  Before: Marsha S. Berzon and Michelle T. Friedland,
Circuit Judges, and Daniel R. Dominguez, * District Judge.

                    Opinion by Judge Berzon




     *
       The Honorable Daniel R. Dominguez, United States District Judge
for the District of Puerto Rico, sitting by designation.
2                     PEREZ CRUZ V. BARR

                          SUMMARY **


                           Immigration

    Granting Gregorio Perez Cruz’s petition for review of a
decision of the Board of Immigration Appeals, the panel held
that Immigration and Customs Enforcement (ICE) agents
were not permitted to carry out preplanned mass detentions,
interrogations, and arrests at a factory, without
individualized reasonable suspicion, and reversed and
remanded to the BIA with instructions to dismiss Perez
Cruz’s removal proceedings without prejudice.

    During the execution of a search warrant for
employment-related documents located at the factory where
Perez Cruz worked, he was detained, interrogated, and
arrested for immigration violations, along with
approximately 130 other workers. He was subsequently
placed in removal proceeding and charged with entry
without inspection. Based on statements he provided during
his detention, ICE prepared a Form I-213, alleging that Perez
Cruz had admitted that he was brought illegally into the
United States as a child. The government also produced
Perez Cruz’s birth certificate based on statements he
provided in connection with the factory raid. Perez Cruz
moved to terminate the proceedings or, in the alternative,
suppress evidence, but the BIA concluded that his detention
and interrogation violated neither the agency’s regulation
nor the Fourth Amendment.



    **
       This summary constitutes no part of the opinion of the court. It
has been prepared by court staff for the convenience of the reader.
                    PEREZ CRUZ V. BARR                      3

    The panel first rejected the government’s contention that,
even if Perez Cruz were otherwise entitled to suppression,
the critical evidence in question constituted evidence only of
“identity” and so was not subject to suppression under INS
v. Lopez-Mendoza, 468 U.S. 1032 (1984). The panel
concluded that this argument was flatly contradicted by
Lopez-Rodriguez v. Mukasey, 536 F.3d 1012 (9th Cir. 2008),
which held that evidence pertaining to alienage is subject to
suppression, and expressly instructed that, however broadly
identity evidence reaches, it does not include evidence
pertaining to alienage. Concluding that Perez Cruz’s
statements regarding his birthplace, and his birth certificate
derived from those statements, constituted evidence of
alienage—not identity—the panel rejected the government’s
argument that the evidence was not suppressible.

    The panel next rejected the government’s contention that
Perez Cruz’s detention was permitted by Michigan v.
Summers, 452 U.S. 692 (1981), which held that a warrant to
search for contraband founded on probable cause implicitly
carries with it the limited authority to detain the occupants
of the premises while a proper search is conducted.

    The panel held that Summers’ categorical authority to
detain incident to the execution of a search warrant does not
extend to a preexisting plan whose central purpose is to
detain, interrogate, and arrest a large number of individuals
without individualized reasonable suspicion. In concluding
that the purpose behind the agents’ conduct was relevant
here, the panel explained that the purpose behind a search or
seizure is often relevant when suspicionless intrusions
pursuant to a general scheme—such as inventory and
administrative searches—are at issue. The panel also
explained that there is no meaningful difference between the
categorical authority to detain without reasonable suspicion
4                   PEREZ CRUZ V. BARR

under Summers and the suspicionless intrusions for which
the Supreme Court has held that a valid purpose is a
prerequisite.

    The panel further observed that, in the context of
determining whether an administrative search is invalid due
to an impermissible purpose, the court asks whether the
officer would have made the stop in the absence of the
impermissible purpose. The panel concluded that Perez
Cruz had satisfied this burden, explaining that ICE planning
documents showed that the central purpose of the raid was
not to find documents but to arrest undocumented workers.

    Accordingly, the panel concluded that Perez Cruz’s
seizure was not a permissible Summers detention and that the
agents therefore violated 8 C.F.R. § 287.8(b)(2), which
requires an immigration officer to have “reasonable
suspicion, based on specific articulable facts, that a person
being questioned is, or is attempting to be, engaged in an
offense against the United States or is an alien illegally in the
United States” in order to briefly detain the person for
questioning. Noting that prejudice may be presumed
where—as here—compliance with a regulation is mandated
by the Constitution, the panel presumed prejudice and
concluded that Perez Cruz was entitled to suppression of the
evidence in question.

    Finally, the panel concluded that the proceedings should
be terminated without prejudice because the government had
not offered any evidence of Perez Cruz’s alienage beyond
the Form I-213 and his birth certificate—fruits of the
regulatory violation. The panel thus granted the petition for
review and remanded to the BIA with instructions to dismiss
his removal proceedings without prejudice.
                    PEREZ CRUZ V. BARR                       5

                         COUNSEL

Ahilian T. Arulanantham (argued), Sameer Ahmed, ACLU
of Southern California, Los Angeles, California; Noemi G.
Ramirez, Los Angeles, California, for Petitioner.

Walter Bocchini (argued), Trial Attorney, Linda S. Wernery,
Assistant Director, Office of Immigration Litigation; Chad
A. Readler, Acting Assistant Attorney General, United
States Department of Justice, Washington, D.C., for
Respondent.

Kristin Macleod-Ball, Melissa Crow, American Immigration
Council, Washington, D.C.; Matthew E. Price, Jenner &
Block LLP, Washington, D.C., for Amicus Curiae American
Immigration Council.


                         OPINION

BERZON, Circuit Judge:

    Immigration and Customs Enforcement (ICE) agents
implemented a preconceived plan to “target” over 200
factory workers for detention and for interrogation as to their
immigration status. The plan turned on obtaining and
executing a search warrant for employment records at the
factory. The record before us establishes that the search
warrant for documents was executed “in order to” arrest
undocumented workers present at the factory. Our central
question is whether the ICE agents were permitted to carry
out preplanned mass detentions, interrogations, and arrests
at the factory, without individualized reasonable suspicion.
We hold that they were not.
6                     PEREZ CRUZ V. BARR

                                  I

                                  A

   In March 2006, ICE received an anonymous tip that
Micro Solutions Enterprises (MSE), a Los Angeles-area
manufacturer of printer cartridges, employed 200 to 300
undocumented immigrants. Nearly two years later, in
February 2008, ICE agents sought and received a search
warrant for employment-related documents located at the
MSE factory in Van Nuys, California, and criminal
complaints and arrest warrants for eight MSE employees. 1

    Documents later obtained 2 revealed that ICE intended
from the outset to turn the execution of these warrants into
quite a different operation than a search for employment
records. An internal memorandum issued before the
operation stated that ICE “[would] be conducting a search
warrant and expects to make 150–200 arrests.” The
memorandum also noted that ICE would have “2 buses and
5 vans” ready to transport potential detainees from the
factory and “200 detention beds available to support the
operation.” Another planning document noted that ICE
“anticipate[d] executing a federal criminal search warrant at


    1
      The record does not reflect why ICE took so long to act on the
anonymous tip.
    2
       These documents were obtained by the ACLU of Southern
California and the Los Angeles Chapter of the National Lawyers Guild
as a result of a Freedom of Information Act (FOIA) request by the
National Immigration Law Center, made after the MSE factory search.
The request resulted in a settlement providing for the release of these
documents, among others. See Order, Nat’l Immigration Law Ctr. v. U.S.
Dep’t of Homeland Sec., No. 2:08-cv-07092-DDP-VBK (C.D. Cal. Feb.
1, 2011), ECF No. 33.
                    PEREZ CRUZ V. BARR                       7

MSE in order to administratively arrest as many as 100
unauthorized workers” (emphasis added).

                              B

    The operation took place as planned. Two days after the
warrants were issued, approximately 100 armed and
uniformed ICE agents streamed into the MSE factory.
Blocking all visible exits, the agents ordered all workers to
stop working and announced that no one was permitted to
leave. The agents prohibited the workers from contacting
anyone using their cellphones and allowed them to use the
restroom only with an ICE escort. Among the workers
detained was Gregorio Perez Cruz, a native and citizen of
Mexico who entered the United States without inspection in
1994.

    The ICE agents then separated the men and women into
different areas. The women were taken to the factory
cafeteria, and the men were instructed to wait in a large
hallway outside the cafeteria. After the men, including Perez
Cruz, had gathered in the hallway, the agents ordered them
to form two lines, one for individuals who possessed work
authorization documents and another for those who lacked
work authorization. Those who joined the line for men who
had work authorization were escorted out of the hallway.
Perez Cruz remained in the hallway but did not join either
line.

   The ICE agents next ordered Perez Cruz and the other
remaining men to stand against the wall. While Perez Cruz
and the others were standing the agents conducted a pat
down of each of them. The agent who frisked Perez Cruz
took his wallet. The detainees were then handcuffed and
questioned. While Perez Cruz was handcuffed, the agents
asked him his name, his nationality, his date of birth, and the
8                   PEREZ CRUZ V. BARR

length of time he had worked at the factory. The agents then
escorted Perez Cruz and the other detained male workers
into another hallway, where they were questioned again. At
some point during his detention, Perez Cruz provided
statements to the agents indicating that he lacked lawful
immigration status.

   Sometime later, the ICE agents began taking groups of
workers to buses parked outside the factory. When it came
time for Perez Cruz to board the bus, an agent photographed
him and asked again for his name and country of origin.
Perez Cruz, still handcuffed, was kept on the bus for over an
hour before he was taken to a detention facility in downtown
Los Angeles.

    When the bus arrived at the detention facility, ICE agents
ordered Perez Cruz off the bus, searched him again, and
removed his handcuffs. Perez Cruz was then held at the
detention facility overnight. During the night, he was
interrogated again. The next day, still detained, Perez Cruz
was interrogated once more. At around 1:00 a.m. he was
released. According to a later ICE press release, Perez Cruz
was one of 130 workers at the MSE factory arrested for
immigration violations.

                              C

    About a month later, Perez Cruz received a notice to
appear for a removal hearing. The notice charged him as
removable for entry without inspection. Based on the
statements Perez Cruz provided during his detention, ICE
agents prepared a Form I-213 alleging that Perez Cruz had
admitted that he was brought illegally into the United States
as a child. In addition to the Form I-213, the government
produced Perez Cruz’s birth certificate, obtained by an ICE
                   PEREZ CRUZ V. BARR                      9

agent in Mexico based on the statements Perez Cruz had
provided in connection with the factory raid.

    Perez Cruz moved to terminate the proceedings or, in the
alternative, suppress the evidence gathered, arguing that his
arrest and interrogation violated binding federal regulations
as well as the Fourth and Fifth Amendments. There was a
brief hearing on Perez Cruz’s motions, during which the
government did not contest any of Perez Cruz’s factual
assertions. The immigration judge (IJ) granted Perez Cruz’s
motion to terminate, concluding that ICE’s initial detention
of Perez Cruz and failure to advise Perez Cruz of his rights
“violated [ICE’s] own regulation.” Relying on Matter of
Garcia-Flores, 17 I. & N. Dec. 325 (B.I.A. 1980), the IJ held
that, because Perez Cruz was prejudiced by this regulatory
violation, termination of his removal proceedings was
warranted. Accordingly, the IJ did not reach Perez Cruz’s
constitutional claims.

    The government appealed, and the Board of Immigration
Appeals (BIA) reversed. The BIA relied on Michigan v.
Summers, 452 U.S. 692 (1981), which held valid the
detention of residents of a home where a search warrant was
being executed. Under Summers, the BIA concluded, Perez
Cruz’s detention and arrest violated neither the agency’s
regulations nor the Fourth Amendment. Because law
enforcement officers are permitted to “secure the premises
both for purposes of their own safety and in order to prevent
the destruction of evidence” during the execution of a
warrant, the BIA reasoned, the ICE agents did not violate the
Fourth Amendment by “ordering employees to stop
working, blocking exits, and asking employees to self-
identify their immigration or citizenship status.” The BIA
also concluded that, even if the detention was improper, the
evidence introduced by the government was offered to prove
10                  PEREZ CRUZ V. BARR

only Perez Cruz’s “identity” and therefore could not be
suppressed.

   On remand from the BIA, the IJ entered a removal order
against Perez Cruz. When Perez Cruz again appealed, the
BIA affirmed the IJ’s order and dismissed the appeal.

    Perez Cruz timely petitioned this court for review of the
BIA’s decisions. He argues, among other things, that his
detention violated both the Fourth Amendment and
controlling regulations, and that the evidence against him
should therefore have been suppressed.

                             II

    We first briefly address the government’s contention that
even if Perez Cruz were otherwise entitled to suppression of
the evidence obtained as a result of the MSE mass detention
and arrest, the critical evidence in question—Perez Cruz’s
statements as represented in the Form I-213, and his birth
certificate—constitutes evidence only of “identity” and so is
not subject to suppression. This argument is squarely
foreclosed by precedent interpreting the reach of INS v.
Lopez-Mendoza, 468 U.S. 1032 (1984).

    Lopez-Mendoza determined that “[t]he ‘body’ or identity
of a defendant or respondent in a criminal or civil proceeding
is never itself suppressible as a fruit of an unlawful arrest,
even if it is conceded that an unlawful arrest, search, or
interrogation occurred.” Id. at 1039. On that basis, Lopez-
Mendoza concluded that an immigrant who “objected only
to the fact that he had been summoned to a deportation
hearing following an unlawful arrest” could not raise a
Fourth Amendment claim. Id. at 1040. We have applied
Lopez-Mendoza beyond the context of mandatory
appearance for trial or hearing, holding that “identity
                       PEREZ CRUZ V. BARR                           11

evidence cannot be suppressed.” United States v. Garcia-
Beltran, 443 F.3d 1126, 1133 (9th Cir. 2006) (emphasis
added). 3

    In Perez Cruz’s removal proceedings, the government
offered statements Perez Cruz made during the factory
interrogation regarding his country of origin. It also offered
his birth certificate, obtained as a result of Perez Cruz’s
statements at the factory about his birthplace. According to
the government, the statements and birth certificate are proof
only of “identity” and therefore not subject to suppression.
That evidence, the government maintains, is sufficient to
establish Perez Cruz’s removability. In so arguing, the
government seeks to expand evidence of one’s identity to
include evidence used to establish alienage—namely, Perez
Cruz’s statements regarding his country of origin and his
birth certificate.

    The government’s position is flatly contradicted by
Lopez-Rodriguez v. Mukasey, 536 F.3d 1012 (9th Cir. 2008).
Lopez-Rodriguez concluded that “evidence of alienage”
resulting from an egregious Fourth Amendment violation—

    3
       Our interpretation of Lopez-Mendoza has not been universally
accepted. The Second, Fourth, Eighth, and Tenth Circuits have held that
Lopez-Mendoza “merely confirmed the jurisdictional rule that an
unlawful arrest has no bearing on the validity of a subsequent
proceeding,” rather than “creat[ing] an evidentiary rule insulating
specific pieces of identity-related evidence from suppression.”
Pretzantzin v. Holder, 736 F.3d 641, 646–47, 646 n.6 (2d Cir. 2013); see
also United States v. Ortiz-Hernandez, 427 F.3d 567, 581–82 (9th Cir.
2005) (W. Fletcher, J., dissenting). We are bound, however, by our
somewhat broader interpretation of Lopez-Mendoza, which accords with
that of several other circuits. See United States v. Chagoya-Morales,
859 F.3d 411, 419 & n.14 (7th Cir. 2017) (collecting cases from this
court, as well as the First, Third, Fifth, Sixth, Seventh, and Eleventh
Circuits).
12                  PEREZ CRUZ V. BARR

namely, the petitioner’s statements “acknowledg[ing] that
she was a native and citizen of Mexico”—should have been
suppressed. Id. at 1014–15. In so concluding, Lopez-
Rodriguez reaffirmed that “the identity of an alien in
removal proceedings is ‘never itself suppressible as a fruit of
an unlawful arrest.’” Id. at 1015 n.5 (quoting Lopez-
Mendoza, 468 U.S. at 1039). But, Lopez-Rodriguez held,
“evidence . . . pertaining to alienage” is subject to
suppression. Id. However broadly “identity” evidence
reaches, Lopez-Rodriguez expressly instructs that it does not
include evidence “pertaining to alienage.” Id.

    Lopez-Rodriguez’s conclusion is bolstered by the
Supreme Court’s reasoning in Lopez-Mendoza itself. Lopez-
Mendoza was careful to distinguish between identity and
alienage, recognizing that, “[s]ince the person and identity
of the respondent are not themselves suppressible, the
[government] must prove only alienage.” 468 U.S. at 1043.
If alienage were bound up in identity, as the government
presently contends, then Lopez-Mendoza would have had no
need to make this point.

    Here, as in Lopez-Rodriguez, the government relied on
alienage evidence alleged to be the fruit of unlawful
government conduct. See 536 F.3d at 1015. The I-213 form
notes, for example, that Perez Cruz “was born in Puebla,
Mexico on 9/6/1985.” Perez Cruz’s birth certificate, too, was
obtained based on his statement that he was born in Puebla,
Mexico. The ICE agent who obtained the birth certificate in
Mexico stated in his declaration that he was assigned to
obtain a birth certificate “for Gregorio Perez, also known as
Gregorio Perez Cruz, who was born on September 6, 1985,
in the State of Puebla Mexico.”

   If Perez Cruz can demonstrate that his statements
regarding his birthplace, and his birth certificate derived
                    PEREZ CRUZ V. BARR                       13

from those statements, were the fruit of impermissible
government action, they are suppressible as evidence of
alienage, not identity. See id. at 1015 n.5. We therefore reject
the government’s argument that the evidence sufficient to
prove Perez Cruz’s removability is not suppressible.

                              III

   We turn to the merits of Perez Cruz’s illegal detention
and interrogation claim.

    As a general matter, the Fourth Amendment’s
exclusionary rule does not apply to immigration
proceedings. See Lopez-Mendoza, 468 U.S. at 1050–51.
There are, however, two longstanding exceptions: (1) “when
the agency violates a regulation promulgated for the benefit
of petitioners and that violation prejudices the petitioner’s
protected interests” and (2) “when the agency egregiously
violates a petitioner’s Fourth Amendment rights.” Sanchez
v. Sessions, 904 F.3d 643, 649 (9th Cir. 2018); see also
Adamson v. Comm’r, 745 F.2d 541, 546 (9th Cir. 1984)
(egregious Fourth Amendment violations); United States v.
Calderon-Medina, 591 F.2d 529, 531–32 (9th Cir. 1979)
(regulatory violations). Perez Cruz argues that suppression
of the evidence in his removal proceedings is warranted
because his detention constituted either a violation of an ICE
regulation or an egregious violation of the Fourth
Amendment.

                               A

   First, did Perez’s detention violate any regulation or the
Fourth Amendment? At this juncture, it does not matter
whether Perez Cruz’s detention is considered under the
regulation or under the Fourth Amendment, because the
14                      PEREZ CRUZ V. BARR

regulatory standards are at least as stringent as those
imposed by the Fourth Amendment.

   Perez Cruz relies primarily on 8 C.F.R. § 287.8(b)(2),
which provides as follows:

         If the immigration officer has a reasonable
         suspicion, based on specific articulable facts,
         that the person being questioned is, or is
         attempting to be, engaged in an offense
         against the United States or is an alien
         illegally in the United States, the immigration
         officer may briefly detain the person for
         questioning.

8 C.F.R. § 287.8(b)(2). Recently, this court recognized that
§ 287.8(b)(2) “serves a ‘purpose of benefit to the alien’” and
that evidence gathered in violation of § 287.8(b)(2) may
therefore be suppressed where “the violation ‘prejudiced
interests of the alien which were protected.’” Sanchez,
904 F.3d at 650 (quoting Garcia-Flores, 17 I. & N. Dec. at
328).

    As Sanchez explained, § 287.8(b)(2) “was intended to
reflect constitutional restrictions on the ability of
immigration officials to interrogate and detain persons in this
country,” thereby providing at least as much protection as
the Fourth Amendment. Id. at 651. 4 Although § 287.8(b)(2)
does not expressly allow for exceptions to its requirements,
both parties assume that a so-called Summers detention
     4
      If anything, the regulation is stricter than the Fourth Amendment.
On its face, the regulation requires reasonable suspicion in every instance
before a person can be detained for questioning by an immigration
officer. See 8 C.F.R. § 287.8(b)(2). So understood, the regulation might
not permit exceptions to the reasonable suspicion requirement.
                    PEREZ CRUZ V. BARR                     15

would be permitted under the regulation. We may likewise
assume that Summers applies to detentions conducted under
§ 287.8(b)(2), as we conclude that, even under Summers, the
detention and interrogation were not permitted.

    The government does not dispute that Perez Cruz was
seized for purposes of the Fourth Amendment when he was
detained in his workplace, frisked, and handcuffed, or that
the ICE agents did so without individualized reasonable
suspicion. Rightly so. The record confirms that the agents
detained Perez Cruz and his coworkers at the outset of the
raid, blocking all exits and prohibiting them from leaving.
That ICE suspected MSE was employing undocumented
workers did not provide reasonable suspicion that Perez
Cruz himself was undocumented. It is a fundamental tenet of
Fourth Amendment law that “a search or seizure of a person
must be supported by probable cause particularized with
respect to that person.” Ybarra v. Illinois, 444 U.S. 85, 91
(1979). Stated differently, “a person’s mere propinquity to
others independently suspected of [unlawful] activity does
not, without more, give rise to probable cause to search [or
seize] that person.” Id.

      “Reasonable suspicion” is no different. “[T]he [Terry v.
Ohio, 392 U.S. 1 (1968)] exception,” for example, “does not
permit a frisk for weapons on less than reasonable belief or
suspicion directed at the person to be frisked, even though
that person happens to be on premises where an authorized
. . . search is taking place.” Id. at 94.

    The government maintains that, despite this bedrock
principle, Michigan v. Summers permitted the agents to
detain Perez Cruz without suspicion on their arrival at the
MSE factory to execute the search warrant they had in hand.
See 452 U.S. at 705. As a result, the government argues, the
agents did not violate the Fourth Amendment or
16                     PEREZ CRUZ V. BARR

§ 287.8(b)(2). The BIA agreed and consequently refused to
suppress the evidence of Perez Cruz’s alienage.

    The parties do not dispute that the underlying search
warrant in this case is of a type that would support a
Summers detention. Cf. Alexander v. City & County of San
Francisco, 29 F.3d 1355, 1363 (9th Cir. 1994), abrogated on
other grounds by County of Los Angeles v. Mendez, 137 S.
Ct. 1539 (2017). 5 We shall so assume. Our inquiry, then,
turns on whether Perez Cruz’s seizure was justified as a valid
Summers detention. It was not.

                                   B

                                   1

    The Fourth Amendment protects “[t]he right of the
people to be secure in their persons, houses, papers, and
effects, against unreasonable searches and seizures.” U.S.
Const. amend. IV. “[T]he general rule,” confirmed by
“centuries of precedent,” is “that Fourth Amendment
seizures are ‘reasonable’ only if based on probable cause.”
Dunaway v. New York, 442 U.S. 200, 213–14 (1979).

    Conversely, if a seizure is supported by probable cause,
“[t]hat action [is] reasonable ‘whatever the subjective intent’
motivating the relevant officials.” Ashcroft v. al-Kidd,
     5
       Alexander held that officers were not entitled to rely on Summers
to detain individuals during the execution of an “administrative
inspection warrant,” reasoning that “[m]any of [Summers’s
justifications] simply do not hold true when the underlying warrant is an
administrative warrant rather than a criminal search warrant.” 29 F.3d
at 1363. Similarly, Sharp v. County of Orange, 871 F.3d 901 (9th Cir.
2017), held that Summers does not provide “the categorical authority to
detain co-occupants of a home incident to the in-home execution of an
arrest warrant.” Id. at 915 (emphasis omitted).
                    PEREZ CRUZ V. BARR                       17

563 U.S. 731, 736 (2011) (quoting Whren v. United States,
517 U.S. 806, 814 (1996)). In other words, “[s]ubjective
intentions play no role in ordinary, probable-cause Fourth
Amendment analysis.” Whren, 517 U.S. at 813. But—and
this point is the critical one for present purposes—“purpose
is often relevant when suspicionless intrusions pursuant to a
general scheme are at issue.” City of Indianapolis v.
Edmond, 531 U.S. 32, 47 (2000) (emphasis added). In those
circumstances, unlike where probable cause or reasonable
suspicion exists, “‘actual motivations’ do matter.’” al-Kidd,
563 U.S. at 736 (emphasis added) (quoting United States v.
Knights, 534 U.S. 112, 122 (2001)); see also Whren,
517 U.S. at 811.

    Consider, for example, the inventory search exception,
under which police may conduct a warrantless search of an
impounded vehicle in accordance with standardized
procedures. See Colorado v. Bertine, 479 U.S. 367, 371
(1987). The Supreme Court has emphasized that “an
inventory search must not be a ruse for a general rummaging
in order to discover incriminating evidence.” Florida v.
Wells, 495 U.S. 1, 4 (1990). Thus, such searches are
permissible only if “there [is] no showing that the police . . .
acted in bad faith or for the sole purpose of investigation.”
Bertine, 479 U.S. at 372; see also United States v. Cervantes,
703 F.3d 1135, 1141 (9th Cir. 2012).

    A similar principle applies to the exception for
administrative searches, which are permitted “when special
needs, beyond the normal need for law enforcement, make
the warrant and probable-cause requirement impracticable.”
Vernonia Sch. Dist. 47J v. Acton, 515 U.S. 646, 653 (1995)
(quoting Griffin v. Wisconsin, 483 U.S. 868, 873 (1987)); see
also Eve Brensike Primus, Disentangling Administrative
Searches, 111 Colum. L. Rev. 254, 276 (2011).
18                  PEREZ CRUZ V. BARR

Administrative searches of public school students, see New
Jersey v. T.L.O., 469 U.S. 325, 341 (1985), or of
probationers, see Knights, 534 U.S. at 121, may be supported
by less than probable cause. And no suspicion at all is
required for enforcement of certain regulatory schemes, such
as routine inspections of residences for housing code
violations, see Camara v. Mun. Court, 387 U.S. 523, 538
(1967), or of businesses in a closely regulated industry, see
New York v. Burger, 482 U.S. 691, 708 (1987). Such
searches do not violate the Fourth Amendment as long as the
government “had proper regulatory purposes for enacting
the administrative scheme” and “[t]here is . . . no reason to
believe that the instant inspection was actually a ‘pretext’ for
obtaining evidence of . . . violation of the penal laws.” Id. at
716 n.27; see also Edmond, 531 U.S. at 41.

    Under these no-probable-cause circumstances, “the
exemption from the need for probable cause (and warrant),
which is accorded to searches made for the purpose of
inventory or administrative regulation, is not accorded to
searches that are not made for those purposes.” Whren,
517 U.S. at 811–12. Without an inquiry into purpose, these
exceptions would provide officers with “a purposeful and
general means of discovering evidence of crime,” which the
Fourth Amendment forbids. Wells, 495 U.S. at 4 (quoting
Bertine, 479 U.S. at 376 (Blackmun, J., concurring)).

    A focus on purpose where there is no probable cause or
reasonable suspicion for the search or seizure effectuates the
original meaning of the Fourth Amendment. “It is familiar
history that indiscriminate searches and seizures conducted
under the authority of ‘general warrants’ were the immediate
evils that motivated the framing and adoption of the Fourth
Amendment.” Payton v. New York, 445 U.S. 573, 583
(1980). “[T]he Amendment’s ban on too-loose warrants
                    PEREZ CRUZ V. BARR                     19

served to reaffirm the common law’s general resistance to
conferring discretionary authority on ordinary officers.”
Thomas Y. Davies, Recovering the Original Fourth
Amendment, 98 Mich. L. Rev. 547, 724 (1999); see also
Laura K. Donohue, The Original Fourth Amendment, 83 U.
Chi. L. Rev. 1181, 1323–24 (2016). The uncabined
discretion potentially provided by these Fourth Amendment
exceptions is not unlike the authority provided by the general
warrants abhorred by the Framers. See Davies, supra, at
736–38. A limit on the permissible purposes for which these
exceptions may be used limits the exceptions to the
circumstances that generated them and so furthers the
original understanding of the Amendment.

                              2

    The authority provided by Summers for detention during
the execution of a valid search warrant applies in the absence
of probable cause or reasonable suspicion as to the detained
individuals’ culpability, and so is analogous to the probable
cause exceptions for which valid purpose is a prerequisite.

    In Summers, police officers detained George Summers
as he left a house at which the officers were preparing to
execute a search warrant. 452 U.S. at 693. The officers
learned during the search that Summers owned the house. Id.
Drugs were found in the basement. Id. The officers then
searched Summers and found an envelope containing heroin
in his coat pocket. Id. Summers was charged with possession
of that heroin. Id. at 694.

     Summers moved to suppress the heroin as a fruit of his
initial detention, for which, he argued, the officers had no
probable cause. Id. at 694. Assuming that the detention “was
unsupported by probable cause,” id. at 696, the Supreme
Court nonetheless upheld it on the ground that “a warrant to
20                  PEREZ CRUZ V. BARR

search for contraband founded on probable cause implicitly
carries with it the limited authority to detain the occupants
of the premises while a proper search is conducted,” id.
at 705 (footnote omitted). Summers thereby created another
limited exception to the Fourth Amendment’s general
requirement that a seizure be supported by probable cause
or, under some circumstances, reasonable suspicion. See
Dunaway, 442 U.S. at 213.

    The Summers exception was reaffirmed in Muehler v.
Mena, 544 U.S. 93 (2005). There, police officers
investigating a gang-related shooting obtained a search
warrant for a suspected gang member’s residence. Id. at 95–
96. During the search the officers handcuffed and detained
Iris Mena, who lived at the residence, and questioned her
about her immigration status. Id. at 96. Mena sued the
officers under 42 U.S.C. § 1983, arguing that the officers
“should have released Mena as soon as it became clear that
she posed no immediate threat” and that, as they had not
done so, her detention violated the Fourth Amendment. Id.
at 96–97. The Court rejected that contention, emphasizing
that “[a]n officer’s authority to detain incident to a search is
categorical; it does not depend on the ‘quantum of proof
justifying detention or the extent of the intrusion to be
imposed by the seizure.’” Id. at 98 (quoting Summers,
452 U.S. at 705 n.19). “[B]ecause a warrant existed to search
[the house] and Mena was an occupant of that address at the
time of the search,” the Court concluded, “Mena’s detention
for the duration of the search was reasonable under
Summers.” Id.

    Summers and Mena both involved searches and
detentions limited in scope. But this court has applied the
Summers exception to cover somewhat broader searches and
detentions. Dawson v. City of Seattle, 435 F.3d 1054 (9th
                      PEREZ CRUZ V. BARR                            21

Cir. 2006), for example, upheld the detention of the residents
of two boarding houses while a search warrant was executed
for evidence of rodent infestation and various municipal
health code violations. Id. at 1066. Likewise, Ganwich v.
Knapp, 319 F.3d 1115 (9th Cir. 2003), upheld the initial
detention of several employees in a waiting room at a
workplace being searched, concluding that “the officers’
holding the [employees] in the waiting room was precisely
the conduct the Supreme Court deemed reasonable in
Michigan v. Summers.” Id. at 1120–21 (citation omitted).6
These cases hold that, as a general matter, “the police may
detain a building’s occupants while officers execute a search
warrant as long as the detention is reasonable.” Dawson,
435 F.3d at 1065. “[T]he duration of a detention may be
coextensive with the period of a search, and require[s] no
further justification.” Id. at 1066.

    There is one critical—indeed, determinative—difference
between those cases and this one. Perez Cruz has presented
substantial, uncontroverted evidence that the search
authorized by the warrant was far from the ICE agents’
central concern. Instead, the agents’ principal goal was to
detain, interrogate, and arrest a large number of individuals
who worked at the MSE factory, hoping to initiate removal
proceedings against them. According to the FOIA-obtained
documents, that was the “target” of the agents’ activity, and
the agents came on the premises “in order to” arrest
undocumented workers. Notwithstanding this transparent
evidence concerning the purpose for entering the MSE

    6
      Ganwich ultimately held that the employees’ detention was
unlawful, as “[t]he officers’ conduct was more intrusive than necessary
to effectuate an investigative detention otherwise authorized by
Summers, so it was not reasonable under the Fourth Amendment.”
319 F.3d at 1124.
22                  PEREZ CRUZ V. BARR

factory, the government asks us to authorize Perez Cruz’s
detention under Summers. We cannot do so.

    As the Supreme Court has explained, “Summers
recognized that a rule permitting the detention of occupants
on the premises during the execution of a search warrant,
even absent individualized suspicion, was reasonable and
necessary in light of the law enforcement interests in
conducting a safe and efficient search.” Bailey v. United
States, 568 U.S. 186, 200 (2013). In permitting such
detentions, “this exception grants substantial authority to
police officers to detain outside of the traditional rules of the
Fourth Amendment.” Id. Where “a safe and efficient search”
is not the primary purpose of the officers’ actions,
Summers’s justification for bypassing the Fourth
Amendment’s traditional protections disappears, id., just as
the justifications for doing so disappear—and so bypass of
the usual Fourth Amendment requisites becomes
impermissible—in inventory and administrative search
cases.

    We recognize that Summers detentions do presuppose a
valid search warrant supported by probable cause. But
search warrants based on probable cause cover the place
being searched, not the seizure of individuals. Summers
requires no reasonable suspicion for an individual’s
detention, nor need the magistrate who issues the warrant be
told about, or approve, any detention of individuals, planned
or otherwise. Again, under Summers, “[a]n officer’s
authority to detain incident to a search is categorical; it does
not depend on the ‘quantum of proof justifying detention or
the extent of the intrusion to be imposed by the seizure.’”
Mena, 544 U.S. at 98 (quoting Summers, 452 U.S. at 705
n.19). There is no meaningful difference between the
categorical authority to detain without reasonable suspicion
                    PEREZ CRUZ V. BARR                      23

during the execution of a search warrant and the
“suspicionless intrusions pursuant to a general scheme” for
which the Supreme Court has held purpose is relevant.
Edmond, 531 U.S. at 47.

    The law enforcement interests underlying Summers are
fully consistent with this conclusion. “In Summers, the Court
recognized three important law enforcement interests that,
taken together, justify the detention of an occupant who is
on the premises during the execution of a search warrant:
officer safety, facilitating the completion of the search, and
preventing flight.” Bailey, 568 U.S. at 194; see also
Summers, 452 U.S. at 702–03. These interests are parallel to
those underlying the Fourth Amendment limitations
applicable to suspicionless searches discussed above.
Inventory searches, for example, are justified by “three
distinct needs: the protection of the owner’s property while
it remains in police custody, the protection of the police
against claims or disputes over lost or stolen property, and
the protection of the police from potential danger.” South
Dakota v. Opperman, 428 U.S. 364, 369 (1976) (citations
omitted). Yet the Supreme Court has long recognized that an
inventory search is impermissible if “the police . . . acted in
bad faith or for the sole purpose of investigation.” Bertine,
479 U.S. at 372. “That Summers detentions aid police in
uncovering evidence and nabbing criminals does not
distinguish them from the mine run of seizures unsupported
by probable cause, which the Fourth Amendment generally
proscribes.” Bailey, 568 U.S. at 206 (Scalia, J., concurring).

    In light of the interests underlying the Summers
exception, the Supreme Court’s reasoning in Bailey strongly
supports the conclusion that Summers does not authorize
Perez Cruz’s detention. Bailey held that officers may not rely
on Summers to detain individuals who are found beyond “the
24                 PEREZ CRUZ V. BARR

immediate vicinity of a premises to be searched.” Id. at 201
(majority opinion). “Limiting the rule in Summers to the area
in which an occupant poses a real threat to the safe and
efficient execution of a search warrant,” Bailey reasoned,
“ensures that the scope of the detention incident to a search
is confined to its underlying justification.” Id. (emphasis
added). The Court explained that, “[o]nce an occupant is
beyond the immediate vicinity of the premises to be
searched, the search-related law enforcement interests are
diminished and the intrusiveness of the detention is more
severe.” Id. Bailey instructs that Summers does not approve
a detention without any individualized suspicion where the
officers’ primary purpose is not conducting “a safe and
efficient search” pursuant to a warrant. Id. at 200. On the
evidence before us, that was precisely the case here—the
agents’ focus was not on conducting a safe search but on
engaging in a preplanned investigation and detention of a
large number of individuals present at the premises where
the search was authorized.

    Notably, in establishing the Summers exception, the
Supreme Court emphasized that “the type of detention
imposed here is not likely to be exploited by the officer or
unduly prolonged in order to gain more information, because
the information the officers seek normally will be obtained
through the search and not through the detention.” 452 U.S.
at 701. That assertion held true for the limited searches
considered in Summers and Mena. But as the permissible
applications of Summers have expanded—covering broader
searches and a greater number of detentions, see, e.g.,
Dawson, 435 F.3d at 1066; Ganwich, 319 F.3d at 1120–21—
so has the potential for abuse.

   As “[a]n exception to the Fourth Amendment rule
prohibiting detention absent probable cause,” the authority
                    PEREZ CRUZ V. BARR                     25

granted by Summers “must not diverge from its purpose and
rationale.” Bailey, 568 U.S. at 194. We hold that Summers’
categorical authority to detain incident to the execution of a
search warrant does not extend to a preexisting plan whose
central purpose is to detain, interrogate, and arrest a large
number of individuals without individualized reasonable
suspicion.

                              3

    That the ICE agents here had some investigatory purpose
in detaining Perez Cruz does not, on its own, invalidate their
reliance on Summers. In applying the purposive limitation
on administrative searches, we have “emphasize[d] that the
presence of a criminal investigatory motive, by itself, does
not render an administrative stop pretextual.” United States
v. Orozco, 858 F.3d 1204, 1213 (9th Cir. 2017). “[A]n
individual suspected of crime may be subjected to facially
valid, broadly applicable search schemes on the same basis
as other individuals—provided those schemes do, in fact,
apply in his case.” United States v. Tsai, 282 F.3d 690, 695
(9th Cir. 2002). Thus, in the administrative search context,
to determine whether the search is invalid because of an
impermissible purpose, “we ask whether the officer would
have made the stop in the absence of the invalid purpose.”
Orozco, 858 F.3d at 1213 (quoting United States. v. Maestas,
2 F.3d 1485, 1489 (10th Cir. 1993)). To meet this standard,
“a defendant must show that the stop would not have
occurred in the absence of an impermissible reason.” Id.

    Perez Cruz has satisfied the Orozco burden. As the ICE
planning documents unmistakably show, the agents’ plans
here were centered on detaining and interrogating any and
all workers located at the MSE factory to determine whether
they were undocumented. One document, for example,
stated that ICE was “targeting 150–200 undocumented
26                  PEREZ CRUZ V. BARR

workers” (emphasis added) during the operation, evidencing
that arresting those workers, and not obtaining the
documents mentioned in the warrant, was the focus of the
operation. In fact, under “significant details” of the operation
listed in that document, the search itself not mentioned at
all—only the “targeted” workers, the “ratio of
apprehensions” of men and women, and the office that ICE
would be using “to detain and process all arrested
individuals.” Another memorandum issued before the raid
explained: “ICE anticipates executing a federal criminal
search warrant at MSE in order to administratively arrest as
many as 100 unauthorized workers believed to be from
Mexico and Central America” (emphasis added). Those
statements alone establish that the central purpose of the raid
was not to find documents but to arrest undocumented
workers.

    Documents prepared after the raid reinforce the
conclusion that the agents were focused on the detentions,
not the search. Those post-raid memoranda don’t mention
the search at all; instead they discuss—in great detail—the
workers’ detention. And another of those documents
confirmed that the operation “targeted approximately 150
undocumented workers believed to be employed at [MSE].”
(emphasis added).

    The ICE agents’ conduct at the MSE factory and
afterward also confirms that they understood the search for
records to be of much less significance—if any—as
compared to the detentions, interrogations, and arrests of
workers. The record suggests that many more agents were
dedicated to seizing the MSE workers than to searching for
documents. Instead of participating in the document search,
those agents present spent time corralling the workers,
separating them by gender, handcuffing them, interrogating
                       PEREZ CRUZ V. BARR                             27

them, and searching them. Transportation and detention
facilities for a large number of anticipated detainees were
readied in advance, confirming that the agents had made
careful plans to arrest these workers and take them offsite,
rather than merely to detain them during the records search.

    The agents’ repeated interrogations of Perez Cruz and his
coworkers during their detention also demonstrate that the
agents’ reliance on the Summers exception was misplaced.
Mena authorizes officers to ask questions of Summers
detainees as long as the detention is not “prolonged by the
questioning.” 544 U.S. at 100–01. But that authorization
does not allow officers to conduct a Summers detention for
the purpose of obtaining answers from detainees, let alone
transporting detainees offsite and holding them long beyond
the length of the search so they can be further interrogated,
as occurred here. Mena did not abrogate the longstanding
requirement that “if the person[] refuses to answer and the
police take additional steps . . . to obtain an answer, then the
Fourth Amendment imposes some minimal level of
objective justification to validate the detention or seizure.”
INS v. Delgado, 466 U.S. 210, 216–17 (1984). 7

    The IJ found that the agents “ordered” Perez Cruz and
the other male workers to address whether they had work
authorization by joining one of two lines. The agents then
repeatedly questioned the workers who did not join the work
authorization line until responses were provided. Perez Cruz,
in particular, declined to answer the initial question, as he

    7
       We have similarly recognized that “law enforcement may not
require a person to furnish identification, if not reasonably suspected of
any criminal conduct.” United States v. Landeros, 913 F.3d 862, 870 (9th
Cir. 2019) (emphasis added); cf. Hiibel v. Sixth Judicial Dist. Court,
542 U.S. 177, 187–88 (2004).
28                     PEREZ CRUZ V. BARR

joined neither line. He was nonetheless detained and
subjected to repeated questioning while detained. The nature
of the agents’ questioning here indicates that they conducted
the detentions for the purpose of engaging in mandatory
interrogations. Mena does not authorize purposely targeted,
mandatory interrogations after an individual declines to
respond, as opposed to questioning incidental to the warrant
execution purpose on which valid Summers detentions may
be based. 8

     Notably, in contrast to the details regarding detentions,
there is no information in the record about the search itself.
It is therefore impossible to determine whether the agents
even searched for the records purportedly sought, how long
the search—if any—took, or whether the records search—if
any—occurred anywhere near where the detentions took
place. 9 This dearth of detail further reinforces the suggestion

     8
      Again, two buses and vans arrived at the factory to detain the
workers. Perez Cruz was detained, interrogated, and arrested at the
factory. He was later transferred to a detention facility where he was
questioned during the day and later that night. The next day, the
questioning continued. He was ultimately released at 1:00 a.m. of the
second night detained.
     9
       Even if some initial detention during a search for documents could
have been justified under Summers, Perez Cruz’s detention likely
exceeded anything that could be considered proper in scope, because the
ICE agents appear to have departed even from the warrant itself. As we
have already noted, the search warrant here authorized a search only for
the employer’s records—presumably, paper documents or electronic
files. Yet, the agents used the warrant’s authority to enter the working
area and detain hundreds of workers. Why a search for records required
going onto the floor of a large printer-cartridge factory is unclear. The
record also suggests that the agents spent most of their time detaining
and interrogating the workers rather than diligently executing the search
warrant. See Ganwich, 319 F.3d at 1124 (“[H]ere the officers did
precisely what the Summers Court warned was improper: the officers
                       PEREZ CRUZ V. BARR                             29

that the search was of secondary concern to the agents.
Notably, that deficiency is entirely the government’s doing,
as it expressly declined to offer any evidence to dispute
Perez Cruz’s version of events.

    In sum, Perez Cruz’s seizure was not a permissible
Summers detention. The government suggests no other basis
for Perez Cruz’s suspicionless detention and mandatory
questioning. The agents thus violated 8 C.F.R. § 287.8(b)(2)
by detaining and questioning Perez Cruz without
“reasonable suspicion, based on specific articulable facts,
that the person being questioned is, or is attempting to be,
engaged in an offense against the United States or is an alien
illegally in the United States.” 8 C.F.R. § 287.8(b)(2). 10


exploited the detention, prolonging it to gain information from the
detainees, rather than from the search.”); cf. Rodriguez v. United States,
135 S. Ct. 1609, 1616 (2015) (noting that the permissible length of a
traffic stop is based on a “reasonably diligent” officer).

     Ultimately, however, we need not decide whether the ICE agents
otherwise exceeded the authority granted by Summers, because, given
the clear evidence in the record here that the plan was focused on the
detention of the workers, not the search for documents, even Perez
Cruz’s initial detention was not justified.
    10
       As we noted above, the standards for § 287.8(b)(2) are at least as
stringent as those applicable under the Fourth Amendment, see supra
Section III.A, so the agents’ actions also violated the Fourth
Amendment. Because suppression is necessitated by the regulatory
violation, we need not reach whether the agents’ Fourth Amendment
violation was egregious. Cf. Orhorhaghe v. INS, 38 F.3d 488, 493 (9th
Cir. 1994). For the same reason, we do not address Perez Cruz’s
argument that his detention and interrogation violated the Fifth
Amendment. See Gonzaga-Ortega v. Holder, 736 F.3d 795, 804 (9th Cir.
2013).
30                     PEREZ CRUZ V. BARR

                                   C

    Ordinarily, for a regulatory violation to warrant
suppression, the violation must have prejudiced the
petitioner. See Garcia-Flores, 17 I. & N. Dec. at 328–29. As
Sanchez recognized, however, there is no need for Perez
Cruz to identify prejudice for a violation of § 287.8(b)(2):
“[W]here, as here, ‘compliance with the regulation is
mandated by the Constitution, prejudice may be presumed.’”
904 F.3d at 652 (quoting Garcia-Flores, 17 I. & N. Dec. at
329). We therefore presume that Perez Cruz was prejudiced
in his removal proceedings by the ICE agents’ decision to
detain and question him without individualized reasonable
suspicion. 11 Because the agents violated 8 C.F.R.
§ 287.8(b)(2), Perez Cruz is entitled to suppression of the
evidence gathered as a result of that violation. See id. at 653.

    Finally, Perez Cruz contends that, if suppression is
warranted, his removal proceedings should be terminated
without prejudice. We agree. This court has recognized that
where evidence of alienage is suppressed and “the
government did not introduce any other evidence tending to
show . . . alienage,” termination of the proceedings is
warranted. Lopez-Rodriguez, 536 F.3d at 1019. Here, the
government has not offered any other evidence of Perez
Cruz’s alienage beyond the Form I-213 and his birth
certificate—fruits of the regulatory violation described
above. We thus conclude that the removal proceedings


     11
       Even if prejudice were not presumed, it is quite apparent that the
ICE agents’ improper detention of Perez Cruz “harmed [his] interests in
such a way as to affect potentially the outcome of [his] deportation
proceedings,” thereby prejudicing him. Calderon-Medina, 591 F.2d
at 532. As we explain in the text, without the contested evidence, there
is no basis in the record for determining Perez Cruz’s alienage.
                   PEREZ CRUZ V. BARR                   31

against Perez Cruz should be terminated without prejudice.
See id.

                            IV

    The Summers line of cases does not justify using the
execution of a search warrant for documents to “target” for
detention, interrogation, and arrest busloads of people who
could not otherwise be detained. The detentions, we
conclude, violated an ICE regulation (as well as the Fourth
Amendment). In light of that regulatory violation, we grant
Perez Cruz’s petition for review and remand to the BIA with
instructions to dismiss his removal proceedings without
prejudice.

  PETITION   GRANTED;                REVERSED          and
REMANDED with instructions.
