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Are Dog-Sniff Searches During Traffic Stops Lawful?

Posted by Dmitry Gorin | Feb 13, 2023

In our law firm's criminal defense practice, police procedures are closely examined for possible Fourth Amendment violations after they seize cash, drugs, or other forms of evidence in a state or federal criminal case. In addition, vehicle traffic stops often lead to a car search without a warrant and the seizure of evidence.

Are Dog-Sniff Searches During Traffic Stops Lawful?

For example, in People v. Ernesto Ayon (Court of Appeals Case # H047360), the Sixth District Court of Appeals reversed a defendant who pleaded guilty to drug-related crimes after his motion to suppress evidence was denied.

Ayon argued that police violated the Fourth Amendment's protection against unreasonable searches and seizures by extending the duration of his initial traffic stop for minor traffic infractions to give them more time to complete a sweep by a drug-detecting dog. 

The Court of Appeals agreed that the delay in allowing the dog sniff was unreasonable and that the trial court denied the motion to suppress.

The Ninth Circuit Court of Appeals reached a contrary conclusion in United States v. Nault (9th Cir. Case No. 20-30231), where the majority found it legal that a motorist in a parking lot was extended to facilitate the dog sniff first because of the need for:

  • To obtain the driver's license and registration, and
  • An officer's observations of the driver's intoxication.

The different outcomes illustrate the fact-bound nature of the Fourth Amendment inquiry regarding traffic stops.

Details of the Ernesto Ayon Case

In the first case, let's review some of the specific details of the Ernesto Ayon case:

  • He is driving around San Jose when multiple police vehicles follow him;
  • His vehicle crossed over into a bicycle lane;
  • His right-hand turn signal failed to illuminate;

While these are both citable traffic infractions under California law, police said later that the traffic stop was a pretext to seek evidence of more severe crimes.

The Court of Appeals' opinion is notable for the breakdown of the traffic stop based on body camera footage, which is critical to its analysis of the Fourth Amendment issue.

A traffic stop begins when a vehicle is pulled over and can't last longer than necessary to effectuate the legitimate purposes of that stop.

Police cross the line into unconstitutional detention of the suspect when they fail to diligently pursue means of investigation reasonably designed to quickly confirm or dispel their suspicions regarding the subject of the investigation. 

Simply put, when police in any way prolong the stop, they engage in a fishing expedition to secure evidence of unrelated offenses; the resulting evidence is obtained in violation of the Fourth Amendment and has to be suppressed.

Less than three minutes into the stop, Ayon provided his license and registration information, which the officers transmitted to dispatch. Then, about three and a half minutes into the stop, the officers ordered him out of his vehicle and began questioning him. 

Dispatch advised the officers that his license was valid at three minutes and thirty-two seconds.  After this, an officer ordered Ayon to the back of his vehicle, where he informed him that the reason for the stop was the bicycle lane infraction. 

Officers asked him if they could “take a quick look” into his vehicle at four minutes and twenty seconds.  He asked why they would search his vehicle over a simple moving violation and whether he could receive a ticket and get on his way. 

He said that the law would not allow a search under these circumstances, and a debate ensued.  An officer accused Ayon of being “hostile” and “confrontational” for refusing consent to search.  Six minutes into the stop, he explicitly denied permission to search.

Ayon was Handcuffed and Detained

After he denied consent to search, Ayon was handcuffed under the pretext that his detention was necessary due to the way he was acting.

About eight minutes into the search, officers asked whether a dog had been requested.  Officers questioned whether he had used drugs, which the court later found to be an additional pretext to extend the stop duration. 

The drug-detecting dog arrived about twelve minutes and forty-five seconds into the stop, which alerted to the suspected presence of drugs around nineteen minutes into the stop. Next, police searched the vehicle and found substantial amounts of multiple narcotics and related paraphernalia.

Analysis by the Court

The Court's analysis is a straightforward application of the standard principle that the legitimate justification for the stop ends once efforts bring the investigation into the basis for the stop has either confirmed or dispelled the officers' suspicions. 

Here, police obtained his license, registration, and license plate number in two minutes and thirty seconds and transmitted that information to dispatch to check for warrants or license issues, which is justified in any traffic stop. 

They received a negative response, meaning all that was left was to write up a citation for the bicycle lane and right-hand signal violations. So instead, police prolonged the stop by another sixteen minutes to allow the drug-detecting dog to complete its sniff procedure.

Several arguments raised by the Attorney General on appeal and by the concurring opinion in the Court of Appeals are noteworthy:

  • The Court rejected the argument that Ayon extended the stop length by being argumentative with the arresting officers;
  • It found that he was within his rights to deny consent and made no hostile, threatening, or aggressive movements;
  • The police officer's displeasure with being denied consent to search did not justify prolonging the stop;
  • The Court rejected the Attorney General's suggestion that performing sobriety checks was a legitimate reason to extend the stop as he was not impaired in any way;
  • the Court of Appeals found that he did not act more nervously than a typical person in a traffic stop.

The majority noted that the officers were involved in a pre-existing drug investigation and had almost certainly pulled him over to further than investigation, not to issue traffic citations. 

While the majority's inclusion of this analysis is beneficial for defense lawyers, the concurring opinion correctly points out that well-established United States Supreme Court precedent that says an officer's subjective reasons for initiating the stop are irrelevant, as the Fourth Amendment's protections extend only to unreasonable searches and seizures.

Just as an officer's improper motivation for stopping a motorist does not transform an objectively justifiable stop into an unlawful one, their proper motivation for stopping a motorist does not transform an objectively unjustifiable stop into a lawful one.   

Details of United States v. Nault

In Nault, the driver's encounter with police was initially the result of mistaken identity.  The officer working in a drug task force was notified that a vehicle of interest was located in a nearby parking lot.

Possession of Methamphetamine

They knew the vehicle was registered and driven by a suspect named Ross, whom they knew to have outstanding warrants. 

Police vehicles blocked the vehicle into the parking space and approached the driver, who turned out to be Nault, not Ross.  When officers asked Nault about Ross's whereabouts, he said she was at a nearby gas station.

During the encounter, officers asked Nault for his license, registration, and proof of insurance.  He appeared fidgety, made erratic movements, had visibly constricted pupils, and was sweating profusely despite it being a chilly day. 

They asked him if he was under the influence of alcohol or drugs, which he denied.  They conducted a DUI investigation, which found a marijuana pipe and brass knuckles.  After his arrest, a drug-detecting dog alerted the vehicle, and a subsequent search found a pistol and a large amount of methamphetamine.

Motion to Suppress

Nault moved to suppress the evidence as fruits of the dog sniff, which he said was unconstitutional because the encounter should have been terminated when police learned that he was the vehicle's driver.

Motion to Suppress Evidence in California

The dissenting judge in the Ninth Circuit reasoned that the only legitimate purpose of the stop was to arrest Ross on her outstanding warrants, and any further detention was unjustified.

The majority based its ruling in favor of the government on the permissibility of requesting identifying information from motorists during a traffic stop. 

Asking for a license, etc., the majority explained, is always part of the “mission” of an officer in a traffic stop because it is related to protecting other motorists by ensuring they are safe to drive, meaning prolonging an encounter for this purpose is permitted.   

The dissent conceded that obtaining ID documents is an acceptable reason to extend a traffic stop but would have held that this was not a traffic stop because he parked in a parking lot, not driving in a public way. He was approached based on the suspicion that Ross was in the vehicle making all the precedents involving traffic stops inapplicable.

Suspicion to Justify a Search

The outcomes in Ayon and Nault are opposite but consistent.  In Ayon, the officers did not form any suspicion to justify prolonged detention. 

He handed over his paperwork to give officers what they needed to write his citation and send him on his way.

Suspicion to Justify a Traffic Search

No other reasonable suspicion materialized during the prolonged period while officers waited for the drug dog to arrive.  In contrast, Nault, the additional suspicion of intoxication, emerged almost immediately while trying to obtain his paperwork. 

To be sure, no traffic citation would have been written as he was not suspected of unlawful driving. Still, based on numerous prior cases, the Ninth Circuit held that getting identifying information from a motorist is always a legitimate part of a traffic stop. 

The dissent's argument that the encounter was not a traffic stop did not persuade most of the panel, so Nault's conviction was upheld.

You can contact our law firm for a case evaluation via phone or the contact form. Eisner Gorin LLP is located in Los Angeles, California.

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About the Author

Dmitry Gorin

Dmitry Gorin is a licensed attorney, who has been involved in criminal trial work and pretrial litigation since 1994. Before becoming partner in Eisner Gorin LLP, Mr. Gorin was a Senior Deputy District Attorney in Los Angeles Courts for more than ten years. As a criminal tri...

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