The Fourth Amendment is one the most recognizable parts of the U.S. Constitution. People are generally aware that police cannot search or seize them without a warrant or probable cause. While most residents of the U.S. may not fully understand the nuances of what “probable cause” entails or what is included in a warrant, there is a collective understanding that no one can be detained without a valid reason. However, less people know what “reasonable suspicion” is. In light of recent immigration enforcement actions, there are now questions as to what constitutes “reasonable suspicion” and what it means to be stopped by an officer who claims to have it.
Under President Trump’s new executive order signed on January 20, 2025, U.S. Immigration and Customs Enforcement (“I.C.E”) has increased its enforcement efforts and detained more undocumented immigrants in a short span than it has in previous years.[i] Although the agency has become efficient, legal experts are concerned that this expedited approach is due to agents circumventing Fourth Amendment protections.[ii]
I.C.E is under a unique standard where they may stop anyone if they have reasonable suspicion that the person does not have appropriate documentation.[iii] Applied here, an I.C.E officer has reasonable suspicion that the person is without documentation based on “specific and articulable facts which, taken together with rational inferences from those facts, reasonably warrant that intrusion.”[iv] At issue, are the type of “articulable facts” I.C.E. seems to be using as of late. Agents are using 1) the person’s “apparent race or ethnicity,” 2) their “presence at a particular location,” 3) their employment, and 4) if they speak Spanish or English with an accent.[v] Some have argued that taking these facts, even under the totality of circumstances, would create an unjust application of enforcement because it is not as grounded in specific facts but rather on broad, generalized categories. Others argue that these are facts that have led officers to successfully seize those without documentation. Although the agency might yield a better “success rate” by looking for those who fall under the category, it also risks ensnaring individuals who are fully documented, including U.S. citizens, who happen to fit the same profile. Los Angeles is a great example of this as there have been multiple events in which U.S. citizens were stopped for questioning solely based on these four factors.[vi]
Precedent establishes that ancestry and race may be considered as factors, but only when accompanied by other articulable, specific facts that provide reasonable suspicion that the individual is undocumented. In United States v. Brignoni-Ponce, a Border Patrol officer “pursued respondent’s car and stopped it, saying later that their only reason for doing so was that its three occupants appeared to be of Mexican descent.”[vii] Although there were three undocumented people found in the vehicle, according to the U.S. Supreme Court, based on the driver’s Mexican descent “alone would justify neither a reasonable belief that they were aliens, nor a reasonable belief that the car concealed other aliens who were illegally in the country.”[viii] Particularly, the Supreme Court placed emphasis on the fact that “[l]arge numbers of native-born and naturalized citizens have the physical characteristics identified with Mexican ancestry. . . .”[ix]
In Perdomo v. Noem, the Ninth Circuit Court of Appeals relied on Brignoni and found that the factors I.C.E agents were using in Los Angeles, “even when considered together… ‘do not demonstrate reasonable suspicion for any particular stop.’”[x] As part of an appeal, the United States District Court for the Central District of California issued an injunction preventing the federal government from detaining individuals solely on the basis of these four facts.[xi] The court held that the agents needed to find additional factors in order to establish reasonable suspicion.[xii] However, there is a potential shift in this rule. As part of the U.S. Supreme Court’s Emergency Docket (i.e., “Shadow Docket”), the Supreme Court has lifted this injunction and granted stay so that I.C.E agents may continue to use these factors as the case continues through the system.
Emergency dockets are often procedural and have no bearing on the actual merits of the case. Thus, precedent is not created in these orders.[xiii] As in other cases in the Shadow Docket, there is not an opinion attached to the order. What is unusual about this grant of stay, however, is the fact that Justice Kavanaugh has decided to write a concurring opinion expressing his views.[xiv] In it, he states that the federal government has reached reasonable suspicion on the basis of these four factors when they are taken with the “totality of the circumstances.”[xv] Justice Kavanaugh specifically states that the “high number and percentage of illegal immigrants in the Los Angeles area” is sufficient context for the four factors to support a finding of reasonable suspicion.[xvi]
In her dissent, Justice Sotomayor sharply criticizes Justice Kavanaugh’s concurring opinion. She states that the purpose of the Fourth Amendment is to prevent the very thing the government is trying to enforce: “seize individuals based solely on a set of facts that ‘describe[s] a very large category of presumably innocent people.”[xvii]
Ultimately, the Ninth Circuit Court of Appeals has no guidance on how to rule on this issue. However, Justice Kavanaugh’s concurrence could influence the Ninth Circuit Court to rule under his analysis of reasonable suspicion, despite the court initially establishing groundwork for what would become Justice Sotomayor’s reasoning.
[i] See The White House, Protecting the American People Against Invasion (Jan. 20, 225) https://www.whitehouse.gov/presidential-actions/2025/01/protecting-the-american-people-against-invasion/ [https://perma.cc/Q4C9-S4KF].
[ii] See Natalia Gurevich, Advocates, Legal Experts Fear US Supreme Court Ruling’s Ramifications for Immigrants, San Franciso Exam’r (Sep. 16, 2025) https://www.sfexaminer.com/news/politics/immigrant-advocates-fear-supreme-court-ruling-ramifications/article_6993490e-3e7d-4f06-99e0-64f51184c89d.html [https://perma.cc/NY8U-GVWG].
[iii] See Marco Poggio, When the Supreme Court Says Using Race Is OK, LAW 360 (Sep. 12, 2025), https://plus.lexis.com/newsstand/law360/article/2385810/?crid=07102e8d-1938-48a6-adb2-18f26394a62f [https://perma.cc/NX28-W3XK] (“Unlike in typical arrests, where the Fourth Amendment requires police to have ‘probable cause,’ immigration stops only require that government agents have ‘reasonable suspicion’ that a person is in the country illegally, a lesser standard.”).
[iv] See Terry v. Ohio, 392 U.S. 1, 21 (1968).
[v] See Perdomo v. Noem, 148 F.4th 656, 45 (9th Cir. 2025).
[vi] See Lindsay Whitehurst, Supreme Court Ends Restrictions on LA Immigration Stops Set After Agents Swept up U.S. Citizens, PBS (Sep. 8, 2025) https://www.pbs.org/newshour/nation/supreme-court-ends-restrictions-on-la-immigration-stops-set-after-agents-swept-up-u-s-citizens [https://perma.cc/6E4S-QR3R].
[vii] See United States v. Brignoni-Ponce, 422 U.S. 873, 875 (1975).
[viii] See id. at 886.
[ix] See id.
[x] See Perdomo, 148 F.4th at 683.
[xi] See BREAKING: Court Prohibits Federal Government from Racial Profiling, Denying Access to Counsel in Immigration Raids, Pub. Couns. (Jul. 12, 2025) https://publiccounsel.org/press-releases/breaking-court-prohibits-federal-government-from-racial-profiling-denying-access-to-counsel-in-immigration-raids-2/ [https://perma.cc/ULH5-3EGZ] (“The first TRO bars immigration agents from stopping individuals without reasonable suspicion and from relying on four factors – alone or in combination – including apparent race or ethnicity; speaking Spanish or English with an accent; presence in a particular location … or the work the person does.”).
[xii] See Order Granting Plaintiff’s Ex Parte Application for Temporary Restraining Order and Order to Show Cause Regarding Preliminary Injunction, at 39, Perdomo v. Noem, 148 F.4th 656 (9th Cir. 2025) (noting that an officer “‘must also observe additional information’” that leads to “‘an objective and particularized suspicion of the person to be stopped.’”).
[xiii] See Pablo Das et al., Deep in the Shadows?: The Facts About the Emergency Docket, 109 Va. L. Rev Online 73, 76 (2023) (noting that “shadow dockets” are thought to have less of an impact because they are not decided on the merits although, it does have the ability to influence lower courts).
[xiv] See Noem v. Perdomo, No. 25A169, 2025 U.S. Lexis 343798 at 1 (Kavanaugh, J., concurring).
[xv] See id. at 6.
[xvi] See id. at 6–7.
[xvii] See id. at 10 (Sotomayor, J., dissenting).
