Can the Police Use a Dog to Sniff a Car for Drugs Without a Warrant?

The Supreme Court says a K-9 sniff during a roadside detention is okay—unless it unreasonably prolongs the stop.

By , Attorney · UC Law San Francisco

An officer pulls you over for a minor traffic violation, eventually hands you a ticket, and then has you wait—for a trained dog to sniff your car. Is that legal?

In Rodriguez v. United States, the U.S. Supreme Court held that, unless they have reasonable suspicion of a crime, the police can't extend a traffic stop in order to conduct a dog sniff. Otherwise, though, officers are generally entitled to use dogs to sniff cars during traffic stops.

Traffic Stops and Sniffing Around

On March 27, 2012, at just around midnight (when else?), a Nebraska police officer saw a Mercury Mountaineer "veer slowly onto the shoulder" of a highway "for one or two seconds and then jerk back onto the road." (Rodriguez v. U.S., 575 U.S. 348 (2015).) Knowing shoulder-driving to be illegal, Officer Struble of the Valley Police Department pulled over the SUV.

Officer Struble happened to be a K-9 officer and have his pooch Floyd riding along. Struble approached the driver and had the usual license/registration/proof-of-insurance exchange with driver Dennys Rodriguez. The officer gathered the paperwork and asked Rodriguez to come with him to the patrol car. Rodriguez asked if he had to, was told he didn't, and decided to stay in his car with his passenger, a man by the name of Pollman.

Struble ran a records check on Rodriguez and then returned to the SUV and talked to Pollman. He requested the passenger's driver's license and questioned him about what the two men were up to. (Pollman explained that they were returning to Norfolk after traveling to look at a for-sale Mustang.)

Struble ran another records check, this one on Pollman. The officer called for a second officer and began writing Rodriguez a warning ticket for the driving violation. He approached the Mountaineer for the third time; he issued and explained the warning to Rodriguez and returned each man's documents. About 20 minutes had passed from the time of the pull-over.

Here's where it got interesting—and why the case made it to the highest court. Officer Struble:

  • asked for and was denied permission to walk Floyd around the SUV
  • told Rodriguez to turn off the vehicle, exit it, and stand in front of the patrol car to wait for the other officer (Rodriguez complied)
  • waited until the second officer arrived, and
  • grabbed Floyd and led him twice around the SUV.

During the second trip around, Floyd indicated that the car held drugs. At this point, seven or eight minutes had passed from the point Struble issued the warning ticket. The police then searched and found a big bag of methamphetamine in the vehicle.

Supreme Court: Police Can't Prolong Traffic Stops to Conduct Dog Sniff

The question for the Supreme Court was whether the dog sniff was legal. If not, the methamphetamine—and the drug case against Rodriguez—would have to be tossed.

Here's what the Court said, by a six-to-three vote.

Police dog sniffs during lawful traffic stops are legal under the Fourth Amendment to the federal constitution (though state constitutions might provide otherwise). (Illinois v. Caballes, 543 U. S. 405 (2005).)

But an officer who doesn't have reasonable suspicion may not extend a traffic stop in order to conduct a dog sniff. The officer who pulls a driver over may not prolong the detention "beyond the time reasonably required to complete" the stop's "mission."

An officer's traffic-stop mission reasonably includes tasks like checking the driver's license, registration, and proof of insurance and running a warrant check. But a dog sniff isn't part of it. Once tasks related to the traffic infraction are or should be complete, the detention must end. The central issue actually isn't whether the dog sniff happens before or after the ticket had been issued—it's whether the sniff makes the stop take any longer than it otherwise would.

The Supreme Court sent Rodriguez's case back down to a lower court to determine whether Officer Struble reasonably suspected criminal activity that would justify the extended detention. But the facts as recited by the Court suggested that he didn't. In that case, the sniff would have been illegal, and the methamphetamine would be inadmissible in court. Likewise, in any case where the police unnecessarily drag out a roadside detention in order to fetch the K-9, any turned-up evidence will normally be no good. (For exceptions and background on the Fourth Amendment, see Understanding Search-and-Seizure Law.)

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