99 Problems and They All Depend on an Impartial Canine

Written By: Jennifer Rose

Texas resident Alek Schott filed a Fourth Amendment challenge arguing video footage reveals local authorities unlawfully pulled him over and searched his car based on a handler-influenced K9 alert. Schott’s complaint, embedded with the deputies’ bodycam footage, shows a deputy asserting that the “only reason” for stopping Schott was because he drifted out of his lane. The deputy then frisked, detained, and interrogated Schott, but none of these measures yielded incriminating information. The deputy called a K9 unit to the scene.

The K9 walkaround led to an alert on Schott’s driver-side door, prompting deputies to conduct a sweeping search of the vehicle. The deputies found no drugs or evidence of criminal activity. Over an hour later, Schott was left on the side of the road with a written warning and a ransacked truck.

Schott claims that dashcam footage shows he did not drift lanes and that bodycam footage shows the K9 handler signaling to the dog just before it alerted. If either claim is proven, the stop and search may have violated the Fourth Amendment. Schott further alleges that, according to statistics and recorded statements by the deputy during the stop, Bexar County has a “policy and custom of using traffic stops as a tool to perform searches and seizures,” circumventing Fourth Amendment protections.

The Fourth Amendment seeks to balance the interests of law enforcement with the protection of individual privacy by prohibiting unreasonable searches and seizures and requiring probable cause for the issuance of a warrant. Probable cause to conduct a search requires a “fair probability that contraband or evidence of a crime will be found in a particular place.” The standard is a “fluid concept” dependent on the totality of circumstances and judicially assessed from the perspective of an objectively reasonable officer.

Long ago, the Supreme Court determined that drug-detecting K9 sniffs are not searches, rejecting the need to establish probable cause for most sniffs but allowing those sniffs to create probable cause for a search, giving rise to decades of debate about an oxymoronic “chicken and egg” conundrum. This article explores how K9s can create probable cause to search during traffic stops and the implications of Schott’s case.

Traffic Stops

A traffic stop constitutes a “seizure” under the Fourth Amendment, and an officer may initiate a brief stop upon probable cause or reasonable suspicion. Reasonable suspicion is a lesser standard than probable cause, defined as a “particularized and objective basis for suspecting criminal activity.” Law enforcement officers have substantial discretion in using their experience, special training, and expertise to make “commonsense judgments and inferences about human behavior.” But reasonable suspicion must be articulable—not a “mere hunch”—and a traffic stop is not unconstitutional simply because the officer made a reasonable mistake of fact or law. Like probable cause, reasonable suspicion is an objective inquiry; an officer’s subjective motives “play no role” in a Fourth Amendment challenge.

Duration is the critical factor for a lawful stop. Officers can perform “certain unrelated checks” during a stop if it does not prolong the process beyond “ordinary inquiries incident to the traffic stop.” Ordinary inquiries must reasonably relate to the initial traffic violation or relevant safety concerns. The Fifth Circuit, governing Texas, provides leeway in prolonging a stop to “dispel or confirm” any new reasonable suspicion of criminal activity that may arise before the ordinary inquiries are complete.

K9-Established Probable Cause

In 1983, the Supreme Court ruled that a “sniff” by a well-trained drug-detecting K9 does not constitute a “search” under the Fourth Amendment if the original seizure is supported by reasonable suspicion. The Court thus exempt K9 sniffs from Fourth Amendment constraints, emphasizing the minimal intrusiveness of the technique in both its manner and the limited information it may reveal. In effect, a K9 alert may establish probable cause for officers to search without a warrant in certain circumstances.

This decision raised uncertainty and disagreement amongst lower courts. In 2005, a state court held that the use of a K9 turned a lawful traffic stop into an unlawful drug investigation, characterizing the dog sniff as “the cause rather than the consequence of a constitutional violation.” The Supreme Court reversed. It reasoned that because interest in possessing contraband cannot be legitimate, and a K9 sniff “only reveals the possession of contraband,” the sniff does not compromise a legitimate privacy interest. To bolster this logic, the Court compared Kyllo v. United States, in which it held unconstitutional the use of a thermal-imaging device on a home because it could reveal non-contraband information, such as what time “the lady of the house takes her daily sauna and bath.”

The Supreme Court only requires that a K9 be well-trained or certified and has rejected “strict evidentiary checklists” for assessing the K9’s reliability. Circuits remain divided on what behavior by K9s is sufficiently reliable to constitute an alert, as the determination hinges on the dog’s training and a handler’s interpretation of its behavior. Some circuits hold that the dog need not give a “final response,” while others maintain that a mere change in behavior cannot establish probable cause. Most caselaw from the Fifth Circuit involves incidents at the southern border, which exceed the scope of this article as a matter of national security. However, the circuit generally holds that a change in behavior is presumptively insufficient to establish probable cause and must be supported by additional evidence of the K9’s training and tendencies.

Schott’s Case and Counterarguments to K9-Established Probable Cause

Schott’s case presents an interesting Fourth Amendment challenge because of the nature and succession of the stop and search. If Schott were not drifting lanes, the deputy may not have had a factual basis to support a traffic stop and may have unreasonably prolonged the process beyond ordinary inquiries. However, the deputies will likely wield their discretion to rebut these claims. Schott’s stronger argument is that the K9’s handler prompted the alert, causing a warrantless search without probable cause. The question is whether the handler can establish that the dog’s behavior was a sufficient alert per its tendencies and notwithstanding the possibility that a signal prompted its final response. Either way, the court must determine whether Bexar County deputies have abused their authority by using traffic stops to facilitate K9 sniffs.

Scholars have quarreled with this body of law for decades. K9s have a significantly powerful sense of smell—220 million olfactory receptors compared to 5 million in humans—making them a highly efficient asset for law enforcement. But the accuracy and reliability of K9 drug detection are unclear. Many narcotic odors to which a K9 alerts are also found in commonly-used household products and on over 90% of US dollars in circulation, although both contain significantly less concentrated amounts than narcotics. If a household product or cash can trigger an alert, K9s may reveal more than just contraband.

Schott’s case illustrates another, perhaps more persuasive, argument regarding unreliability: the potential for handlers to influence an alert. Even if we assume most officers act in good faith, dogs inherently “react to subtle, or even subconscious messages from their handlers.” Potential handler influence removes the dog’s objectivity—its neutrality and reliability to expose only contraband—part of the justification for allowing K9s to establish probable cause. A K9 alert may “cloak an officer’s decision to search with both a suspicion of criminal activity and an appearance-of-impartiality that can cover for other, more insidious human motivations,” such as racial biases. But since an officer’s motives play no role in the reasonableness inquiry under the Fourth Amendment, it provides little to no protection against handler-influenced K9 sniffs.

Scooby Snacks for Thought

Persuasive arguments exist on both sides of this debate. The traditional warrant requirement acknowledges that an “officer engaged in the often competitive enterprise of ferreting out crime” may not always objectively assess the circumstances. A neutral judicial officer who determines whether there is probable cause to issue a warrant thus serves as a “checkpoint” of constitutionality. Can a K9 serve this same purpose, or has the risk of handler influence become too great? Maybe it is time to revisit the broad parameters of K9 paws in the laws. Should the chicken still come before the egg, or…?


Article, Investigations and Police Practices, Geo. L.J. Ann. Rev. Crim. Proc. 3 (2022).

Complaint, Alek Schott v. Joel Babb et al., No. 5:23-cv-706 (W.D. Tex., filed June 1, 2023).

Daniel Kaseff, Note: Far-Fetched Uses of Drug Detection Dog Alerts: A Case Note on United States v. Braddy, 44 Cardozo L. Rev. 359 (2022).

Florida v. Harris, 568 U.S. 237 (2013).

Heien v. North Carolina, 574 U.S. 54 (2014).

Illinois v. Caballes, 543 U.S. 405 (2005).

J. Justin Wilson, Lawsuit: Texas Sheriff’s Deputy Falsifies Traffic Offense to Justify Unwarranted Truck Search, THE INSTITUTE OF JUSTICE (June 6, 2023).

Jacey Lara Gottlieb, Note: Who Let the Dogs Out—and While We’re at It, Who Said They Could Sniff Me?: How the Unregulated Street Sniff Threatens Pedestrians’ Privacy Rights, 82 Brooklyn L. Rev. 1377 (2017).

Kansas v. Glover, 140 S. Ct. 1183 (2020).

Kyllo v. United States, 533 U.S. 27 (2001).

Leslie A. Shoebotham, Articles and Brief of Amici Curiae, Fourth Amendment Scholars in Support of Respondent, Florida v. Clayton Harris: Off the Fourth Amendment Leash?: Law Enforcement Incentives to Use Unreliable Drug-Detection Dogs, 14 Loy. J. Pub. Int. L. 251 (2012).

Lewis R. Katz & Aaron P. Golembiewski, Article: Curbing the Dog: Extending the Protection of the Fourth Amendment to Police Drug Dogs, 85 Neb. L. Rev. 735 (2007).

Rodriguez v. United States, 575 U.S. 384 (2015).

Steagald v. United States, 451 U.S. 204 (1981).

United States v. Place, 462 U.S. 696 (1983).

United States v. Reyes, 963 F.3d 482 (5th Cir. 2020).

United States v. Rivas, 157 F.3d 364 (5th Cir. 1998).

Whren v. United States, 517 U.S. 806 (1996).