United States Court of Appeals 

for the Fifth Circuit ____________ 

No. 23-40366 

____________ 

United States of America, 

Plaintiff—Appellee, 

versus

Buzzy Martinez, 

Defendant—Appellant. 

______________________________ 

Appeal from the United States District Court 

for the Southern District of Texas 

USDC No. 2:22-CR-509-1 

______________________________ 

Before Dennis, Southwick, and Ho, Circuit Judges.

James L. Dennis, Circuit Judge: 

Defendant-Appellant Buzzy Martinez was arrested and charged with 

transporting undocumented aliens hidden in his tractor-trailer after a U.S. 

Border Patrol (USBP) canine alerted to the vehicle. Martinez sought to 

suppress evidence gathered from his vehicle, arguing the canine’s alerts 

could not provide his handler the necessary reasonable suspicion to extend 

the stop of his vehicle and probable cause to search it because dogs are unable 

to reliably differentiate between the scents of a vehicle’s driver and concealed 

humans within the vehicle. The district court denied Martinez’s motion to 

United States Court of Appeals 

Fifth Circuit 

FILED 

May 17, 2024 

Lyle W. Cayce 

Clerk 

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No. 23-40366 

2 

suppress, Martinez pleaded guilty, and he now appeals the suppression 

ruling. We AFFIRM. 

I. 

On July 23, 2022, Martinez arrived at the USBP checkpoint in 

Falfurrias, Texas, driving a tractor-trailer. Working at the checkpoint that 

day were USBP Agent Steven Compton, a canine handler, and his canine, 

“Bak.” 

Agent Compton has been a USBP canine handler for seven years and 

has handled three different canines, including Bak. To become a canine 

handler, he trained at the USBP Canine Academy for seven weeks, where he 

learned how to properly care for and train a canine in how to detect 

contraband. He passed a written examination at the end of this training. 

Agent Compton has since passed certification—which tests the canine team 

in seventeen scenarios—with each of his three canines. 

Bak is a canine trained and certified to detect concealed humans and 

controlled substances. Bak responds to contraband in two ways: (1) he may 

“alert,” which refers to the canine’s immediate response to stimulus, 

including respiratory and posture changes as well as more aggressive signals, 

after having identified something he has been trained to detect; and (2) he 

may “indicate,” which is a more passive response the canine is trained to 

perform when the canine has found the source of what it has detected—

which, in Bak’s case, is sitting. After successfully indicating contraband, Bak 

is rewarded with a toy. Bak went through his initial training process with a 

different handler. After four successful certifications with that handler, Bak 

was paired with Agent Compton. Agent Compton then trained with Bak for 

fifteen days, and the team passed certification on July 21, 2022, two days 

before the events underlying this case. 

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On the day of the events in this case, as Martinez drove down the 

primary inspection lane toward the primary inspection point, Agent 

Compton and Bak walked alongside the vehicle conducting a “free air sniff.” 

Bak immediately alerted to Martinez’s tractor-trailer by pulling Agent 

Compton toward the vehicle. When Martinez’s tractor-trailer stopped at the 

primary inspection area to answer immigration questions from the primary 

inspection agent, Bak again alerted by jumping and hitting his paws against 

the rear cab area of the tractor. Bak then indicated by sitting down next to the 

rear of the cab. Bak did this process two more times, jumping against the rear 

of the cab, then sitting. 

Agent Compton, recognizing Bak’s alerts and indications, instructed 

the questioning agent to refer Martinez and his tractor-trailer to the 

secondary inspection area. Once at secondary, agents asked Martinez to step 

out of the vehicle and, after he did so, asked whether anyone else was inside, 

to which Martinez replied there was no one else. Agent Compton and Bak 

then approached for a secondary sniff of the vehicle to confirm Bak was not 

alerting to Martinez. Bak again alerted to the cab by jumping against the door. 

Bak then hesitated, but he did not fully sit down, i.e., indicate. Agent 

Compton opened the driver’s door, and Bak jumped into the vehicle and 

went straight to the rear of the cab. Agent Compton searched the cab and 

found ten individuals concealed in the sleeper area and closets, all of whom 

were determined to be undocumented immigrants. 

Martinez was arrested and charged by indictment with three counts of 

transporting an undocumented alien, in violation of 8 U.S.C. §§ 

1324(a)(1)(A)(ii), (A)(v)(II), and (B)(ii). Martinez filed a motion to suppress 

all evidence resulting from the search of his tractor-trailer, arguing Agent 

Compton lacked reasonable suspicion to lengthen his stop and probable cause 

to search his tractor-trailer because Bak’s alerts and indications were 

unreliable. Martinez’s primary argument was that dogs like Bak are too short 

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4 

to see into the driver’s window of a tractor-trailer and, under these 

circumstances, a dog cannot reliably differentiate between the scents of the 

driver and any other concealed humans in the vehicle. 

After a two-day suppression hearing, the district court issued a written 

order denying Martinez’s motion to suppress. The court found that Agent 

Compton and Bak were adequately trained and certified to detect concealed 

humans, that the USBP training program is sound, and that dogs are capable 

of detecting concealed humans. Accordingly, the court found that Bak’s 

alerts and indications were reliable. The court consequently found that Bak’s 

alerts and indications at the initial inspection provided reasonable suspicion 

for Agent Compton to extend the stop for a second sniff, and Bak’s alerts at 

the second inspection after Martinez was removed from the vehicle provided 

probable cause to search Martinez’s tractor-trailer. 

After the district court’s ruling, Martinez agreed to plead guilty to one 

count of transporting an undocumented alien, pursuant to a conditional plea 

agreement preserving his right to appeal the suppression ruling. At 

sentencing, on June 13, 2023, the district court granted Martinez a downward 

variance and sentenced him to eighteen months in prison, to be followed by 

a term of supervised release of three years. Martinez timely appealed. 

II. 

When reviewing a ruling on a motion to suppress, we review factual 

findings for clear error and legal conclusions de novo, viewing the evidence in 

the light most favorable to the prevailing party, here, the Government. 

United States v. Zavala, 541 F.3d 562, 573–74 (5th Cir. 2008) (citing United 

States v. Ibarra, 493 F.3d 526, 530 (5th Cir. 2007)). The determination that 

there was reasonable suspicion or probable cause is a legal conclusion 

reviewed de novo. See id. (citing Ibarra, 493 F.3d at 530). The reliability of a 

canine’s alert is a factual finding reviewed for clear error. United States v. 

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5 

Outlaw, 319 F.3d 701, 704 (5th Cir. 2003); United States v. Gonzales, 79 F.3d 

413, 418 n.11 (5th Cir. 1996). “A factual finding that is plausible based on the 

record as a whole is not clearly erroneous.” United States v. Ochoa-Gomez, 

777 F.3d 278, 282 (5th Cir. 2015) (citing United States v. Zuniga, 720 F.3d 

587, 590 (5th Cir. 2013)). “Where a district court’s denial of a suppression 

motion is based on live oral testimony, the clearly erroneous standard is 

particularly strong because the judge had the opportunity to observe the 

demeanor of the witnesses.” United States v. Gibbs, 421 F.3d 352, 357 (5th 

Cir. 2005) (quoting United States v. Santiago, 410 F.3d 193, 197 (5th Cir. 

2005)). In the absence of a warrant, the burden of proof is on the Government 

to justify the search. United States v. De La Fuente, 548 F.2d 528, 533 (5th 

Cir. 1977) (citing Manuel v. United States, 355 F.2d 344 (5th Cir. 1966)). This 

court may affirm on any basis established by the record. United States v. 

Powell, 732 F.3d 361, 369 (5th Cir. 2013) (citing United States v. Ibarra–

Sanchez, 199 F.3d 753, 758 (5th Cir. 1999)). 

III. 

 The Fourth Amendment protects against “unreasonable searches and 

seizures.” U.S. Const. amend. IV. “The stopping of a vehicle and 

detention of its occupants constitutes a ‘seizure’ under the Fourth 

Amendment.” United States v. Brigham, 382 F.3d 500, 506 (5th Cir. 2004) 

(en banc). “Ordinarily, a search or seizure is unreasonable ‘in the absence of 

individualized suspicion of wrongdoing.’” United States v. Tello, 924 F.3d 

782, 786 (5th Cir. 2019) (quoting City of Indianapolis v. Edmond, 531 U.S. 32, 

37 (2000)). However, as a “narrow exception to the general requirements of 

reasonable suspicion and probable cause,” the Supreme Court has held that 

border agents at immigration checkpoints may “stop travelers without 

suspicion for questioning about immigration status.” United States v. 

Machuca-Barrera, 261 F.3d 425, 431 (5th Cir. 2001) (citing United States v. 

Martinez–Fuerte, 428 U.S. 543 (1976)). 

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Like any traffic stop, “the tolerable duration” of a stop at an 

immigration checkpoint “is determined by the seizure’s ‘mission,’” and the 

stop “may ‘last no longer than is necessary to effectuate th[at] purpose.’” 

See United States v. Rodriguez, 575 U.S. 348, 354 (2015) (second alteration in 

original) (first quoting Illinois v. Caballes, 543 U.S. 405, 407 (2005); and then 

quoting Florida v. Royer, 460 U.S. 491, 500 (1983) (plurality op.)). At a border 

checkpoint, the permissible duration is “the time necessary to ascertain the 

number and identity of the occupants of the vehicle, inquire about citizenship 

status, request identification or other proof of citizenship, and request 

consent to extend the detention.” Machuca-Barrera, 261 F.3d at 433. To 

extend a stop beyond the time necessary to investigate normal immigration 

matters, the border agent must develop “reasonable suspicion of other 

criminal activity,” and “[f]or extended detentions or for searches,” the agent 

must have “consent or probable cause.” Id. at 434 (citing Martinez-Fuente, 

428 U.S. at 567). “[A] border patrol agent may refer a car to secondary 

[inspection] for any reason (or no reason at all),” but “the length of the 

detention is still limited by the immigration-related justification for the 

stop.” Id. at 434 n.29 (citing United States v. Jackson, 825 F.2d 853, 862 (5th 

Cir. 1987)). A canine sniff of the outside of a vehicle is not a search, United 

States v. Dovali-Avilia, 895 F.2d 206 (5th Cir. 1990) (citing United States v. 

Lovell, 849 F.2d 910, 913 (5th Cir. 1988)), and accordingly during the time 

necessary to investigate normal immigration matters, border agents may 

conduct a canine sniff to search for drugs or concealed aliens so long as 

“conducting the sniff does not prolong the purpose of the stop,” Tello, 924 

F.3d at 787 (first citing United States v. Ventura, 447 F.3d 375, 378 (5th Cir. 

2006); and then citing Rodriguez, 575 U.S. at 357). 

An agent has probable cause to search when, considering the totality 

of the circumstances, “the facts available to him would warrant a person of 

reasonable caution in the belief that contraband or evidence of a crime is 

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present.” Florida v. Harris, 568 U.S. 237, 243 (2013) (cleaned up) (quoting 

Texas v. Brown, 460 U.S. 730, 742 (1983) (plurality opinion)). Probable cause 

requires only “the kind of ‘fair probability’ on which ‘reasonable and 

prudent [people,] not legal technicians, act.’” Id. at 244, 249 (alteration in 

original) (quoting Illinois v. Gates, 462 U.S. 213, 238 (1983)). “[W]e do not 

evaluate probable cause in hindsight, based on what a search does or does not 

turn up.” Id. at 249 (citing United States v. Di Re, 332 U.S. 581, 595 (1948)). 

“‘Reasonable suspicion is a low threshold’ and requires only ‘some 

minimal level of objective justification.’” United States v. Smith, 952 F.3d 

642, 648 (5th Cir. 2020) (quoting United States v. Castillo, 804 F.3d 361, 367 

(5th Cir. 2015)). “Reasonable suspicion demands something more than a 

‘mere hunch’ but ‘considerably less than proof of wrongdoing by a 

preponderance of the evidence, and obviously less than is necessary for 

probable cause.’” Id. (cleaned up) (quoting Navarette v. California, 572 U.S. 

393, 397 (2014)). 

When a dog that is “trained to alert . . . [to] contraband or people” 

does so “alert[] in the near presence of a particular vehicle, that action is 

sufficient to give rise to probable cause to search that vehicle.” Dovali-Avila, 

895 F.2d at 207. “A defendant, however, must have an opportunity to 

challenge . . . a dog’s reliability.” Harris, 568 U.S. at 247. 

The Supreme Court addressed how courts should evaluate a dog’s 

reliability in Florida v. Harris, 568 U.S. at 243–48. “The question—similar 

to every inquiry into probable cause—is whether all the facts surrounding a 

dog’s alert, viewed through the lens of common sense, would make a 

reasonably prudent person think that a search would reveal contraband or 

evidence of a crime.” Id. at 248. The Court emphasized a dog’s performance 

in “controlled testing environments” over “[f]ield data.” Id. at 246. 

“[E]vidence of a dog’s satisfactory performance in a certification or training 

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program can itself provide sufficient reason to trust his alert.” Id. “If a bona 

fide organization has certified a dog after testing his reliability in a controlled 

setting, a court can presume (subject to any conflicting evidence offered) that 

the dog’s alert provides probable cause to search.” Id. at 246–47. However, 

a defendant “may contest the adequacy of a certification or training program, 

perhaps asserting that its standards are too lax or its methods faulty,” and 

may “examine how the dog (or handler) performed in the assessments made 

in those settings.” Id. at 247. Furthermore, “evidence of the dog’s (or 

handler’s) history in the field, . . . may sometimes be relevant,” and “even 

assuming a dog is generally reliable, circumstances surrounding a particular 

alert may undermine the case for probable cause—if, say, the officer cued the 

dog (consciously or not), or if the team was working under unfamiliar 

conditions.” Id. 

 On appeal, Martinez renews his attack on the adequacy of Bak’s 

training. He argues a dog cannot be reliably trained to differentiate between 

the scents of the driver and other concealed humans in a vehicle. 

Accordingly, he argues Bak’s alerts and indications did not provide Agent 

Compton reasonable suspicion to extend his stop and probable cause to 

search his tractor-trailer. That argument fails for two reasons. 

 First, by focusing on a dog’s ability to detect concealed humans, 

Martinez improperly parses the situation in hindsight, rather than examining 

it through the totality of Agent Compton’s experience in the moment. The 

record shows that Bak is trained and certified to detect both concealed 

humans and controlled substances. When Bak alerted to Martinez’s tractortrailer, a reasonable person could have thought Bak was detecting either 

concealed humans or controlled substances. Of course, Bak actually found 

concealed humans, but “we do not evaluate probable cause in hindsight, 

based on what a search does or does not turn up.” Id. at 249 (citing Di Re, 

332 U.S. at 595). Martinez does not challenge Bak’s ability to detect 

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controlled substances, a skill he is certified in. “If the [Government] has 

produced proof from controlled settings that a dog performs reliably in 

detecting drugs, and the defendant has not contested that showing, then the 

court should find probable cause.” Id. at 248. Because Bak is trained and 

certified to detect controlled substances, which Martinez does not contest, 

his alert provided Agent Compton reasonable suspicion to investigate for and 

probable cause to search for controlled substances. See Powell, 732 F.3d at 369 

(stating this court may affirm on any basis established by the record); cf. 

Outlaw, 319 F.3d at 704 (holding that the alert of a dog that was reliably 

certified to detect marijuana, cocaine, heroin, and methamphetamine 

provided reasonable suspicion, even though the briefcase the dog alerted to 

actually contained phencyclidine, known as PCP, which the dog was not 

trained to detect); United States v. Viera, 644 F.2d 509, 511–12 (5th Cir. Unit 

B May 1981) (holding that the alerts of dogs that were trained to detect 

heroin, cocaine, hashish, marijuana, and related drugs provided probable 

cause, even though the briefcases the dogs alerted to actually contained 

quaaludes, which the dogs were not trained to detect). 

 Second, even evaluating Bak’s ability to detect concealed humans, the 

district court’s finding that Bak was reliable in this regard is not clearly 

erroneous. The district court found Martinez’s argument that dogs cannot 

differentiate between the scents of different concealed humans to be 

speculative and noted the ability of rescue dogs to find people buried under 

rubble and to work around the obvious or other people engaged in the search 

and rescue operation. The court also noted Bak can go weeks without an alert, 

controverting Martinez’s argument that Bak is alerting to the smell of the 

drivers or responding to cues. The court examined the standards of USBP’s 

training program and noted USBP has been training canines to detect 

concealed humans for nearly forty years with reliable results in testing. Both 

Bak and Agent Compton are trained and certified through USBP’s program 

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and have continued to receive above-average scores on their bi-weekly 

trainings. Because the court’s conclusion that Bak was reliable is “plausible 

in light of the record as a whole,” it is not clearly erroneous. See OchoaGomez, 777 F.3d at 282. 

 Based on this finding, the district court correctly held Bak’s alerts and 

indications at the primary inspection point provided Agent Compton 

reasonable suspicion to extend the stop and investigate for concealed 

humans. See Machua-Barrera, 261 F.3d at 434. Further, the district court also 

correctly held that, at the secondary inspection point, after Martinez exited 

the vehicle1

 and stated no one else was inside, Bak’s continued alerts to the 

cab area of Martinez’s tractor-trailer provided probable cause to search the 

cab for concealed humans. See Harris, 568 U.S. at 248; Dovali-Avila, 895 

F.2d at 207; Machua-Barrera, 261 F.3d at 434. 

IV. 

 The judgment of the district court is AFFIRMED. 

_____________________ 

1

 It is well established that, once a vehicle has been lawfully stopped, officers may 

order the driver out of the vehicle without violating the Fourth Amendment due to 

concerns for officer safety. See, e.g., Pennsylvania v. Mimms, 434 U.S. 106, 111 (1977); United 

States v. Meredith, 480 F.3d 366, 369 (5th Cir. 2007). That objective justification remains, 

“subjective thoughts notwithstanding,” i.e., even if the officer has different subjective 

intentions for ordering the driver out of the vehicle, such as, here, to conduct a secondary 

sniff. See Ohio v. Robinette, 519 U.S. 33, 38 (1996). 

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