Criminal Law

Drug-Sniffing Dogs and Traffic Stops

By John McCurley, Attorney
The rules for when police can bring in a canine to sniff your car for drugs during a roadside detention.

The sensitive noses of drug dogs give law enforcement an effective tool for detecting illegal drugs. For this reason, narcotics-sniffing dogs are a common sight in airports and border crossings. But what about when police employ the services of a drug-sniffing canine during a routine traffic stop? Is it illegal for police to walk a dog around your car while you wait?

Police can use drug-detection dogs during traffic stops—but there are limits.

First Things First: What’s the Reason for the Stop?

Dog or no dog, police must have a legitimate reason for pulling you over. In other words, police need to have reasonable suspicion that the driver—or someone else in the car—has violated the law. A minor traffic violation such as speeding or running a red light will normally suffice. Traffic stops without valid justification, however, are illegal. Typically, all evidence police find following an illegal detention will be inadmissible in court—including drugs discovered by a drug-sniffing dog. (Learn more about how the “exclusionary rule” applies to illegal police searches.)

Don’t Police Need Probable Cause of a Drug Offense?

Police had a valid reason for stopping me, a traffic violation. But my citation had nothing to do with drugs. Don’t police need probable cause of a drug offense before bringing in a drug dog? Nope.

But wait—a minor traffic violation generally doesn’t give an officer the right to search a car and its occupants. (Read more about searches following traffic stops.) So why then can police use a dog to search a car for drugs?

The U.S. Supreme Court answered this question in Illinois v. Caballes. There, an officer pulled the defendant over for speeding. As the officer was making the stop, he radioed in to dispatch and reported his status. A second officer overheard the transmission and responded to the scene with a drug-detection dog. While the first officer was issuing a warning for the speeding violation, the second officer walked around the defendant’s car with the dog. Having been alerted by the dog, police searched and found marijuana in the trunk.

The defendant argued that the sniff was an illegal search and seizure—a violation of his Fourth Amendment rights. The Supreme Court, however, didn’t buy it.

The Court said that drivers don’t have a “reasonable expectation of privacy”—a requirement for Fourth Amendment protection—in the smell of their vehicles. So, the officer’s use of a narcotics-detecting canine didn’t constitute the type of search that’s protected by the federal constitution. (Illinois v. Caballes, 543 U.S. 405 (2005).)

Are There Limits?

Some law enforcement felt Caballes gave them carte blanche to use a dog during any traffic detention. Officers with this mindset would complete a traffic stop then make the motorist wait for a canine unit to arrive. Oftentimes, the result was an unnecessarily long roadside detention.

In Rodriguez v. U.S., the Supreme Court declared this practice illegal. The Court said that an officer who doesn’t have reasonable suspicion (other than for the traffic violation) can’t prolong a stop to conduct a dog sniff. In other words, a dog sniff is legal only if it doesn’t extend the detention “beyond the time reasonably to complete” the traffic stop. (Rodriguez v. U.S., 135 S.Ct. 1609 (2015).)

Example: While driving cross country, Patrick was stopped by a Nevada Highway Patrol officer for having a taillight out. The officer issued Patrick a warning for the taillight. But instead of letting Patrick go, the officer started explaining his general concern about cross-state drug trafficking. The officer asked if Patrick would mind waiting for a canine unit to arrive. Patrick sympathized with the officer’s concern, but said that he would rather get back on the road. Under Rodriguez, the officer can’t make Patrick wait.

(For more about Rodriguez v. U.S., see Traffic Stops and Police Dog Sniffs.)

Questions for an Attorney

  • Is it illegal for an officer to let a dog walk on top of my car?
  • How long should it take police to complete a traffic stop?
  • If police illegally prolong a traffic stop, will any evidence they find be thrown out?
  • Do all states follow the Rodriguez rule?
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