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Can drug-sniffing dogs make mistakes?

On Behalf of | May 8, 2025 | Criminal Defense

Seeing red and blue lights flash in your rearview mirror can make any driver panic. You pull over, and minutes into the traffic stop, the officer mentions a K9 unit is on the way. Suddenly, what seemed like a routine stop feels much more serious. As the dog circles your vehicle, you wonder: Just how reliable are these animals at detecting drugs?

What happens during a K9 traffic stop?

Officers may use a drug-sniffing dog during a traffic stop to detect illegal substances. In Indiana, the law allows this, but it’s essential to know your rights. Police can’t detain you indefinitely while waiting for a K9 unit. The dog’s sniff should be quick and not cause unnecessary delays.

Further, never forget that you have the right to remain silent and refuse consent to search your vehicle without probable cause or a warrant.

Can police dogs make mistakes?

Drug-sniffing dogs and their handlers undergo training and certification, but this doesn’t make them perfect. Studies show these dogs can be wrong surprisingly often.

Drug dogs can and do give false alerts. A “false alert” happens when a dog signals for drugs, but no drugs are there. This can happen for several reasons:

  • Dogs can pick up on subtle handler cues, alerting when the handler suspects drugs
  • Residual odors from previous drug presence can trigger alerts even when no drugs exist
  • Dogs may alert to similar-smelling legal substances
  • Some handlers reward dogs for alerting, which can encourage false positives

Rates vary between dogs, handlers and police departments, but it is not unusual for a dog to have an error rate of over 50 percent. These error rates mean that just because a dog “alerts” on your vehicle, it doesn’t automatically mean drugs are present.

What to do during a traffic stop with a K9

If police stop you and a drug dog appears, stay calm and remember your rights. First, be polite but minimal in your responses to questions. Don’t volunteer information.

If possible, document everything about the stop. Note the time the stop began and how long it took for the K9 to arrive. If the dog alerts, watch carefully for any handler behaviors that might influence the animal.

Drug-sniffing dogs are tools used by law enforcement, but they’re not infallible. Knowing your rights during traffic stops helps protect you from potential mistakes and wrongful conviction.

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