Tank the police dog is a good boy caught in a bad situation. But don’t blame him. When a federal court criticized the reliability of every drug K-9 in Utah on April 21, the rebuke had more to do with human behavior than anything else.

People can’t sniff out trace amounts of narcotics, but the humans in charge of law enforcement speak on behalf of the dogs who do. And sometimes, often unintentionally, the people who control training, certification and fieldwork cue behavior from their K-9 partners to get desired results.

Tank knows nothing about the stimulus and response. He’s just a pleaser who shows up eager for work at the West Valley City Police Department. He can read body language, but not the court order throwing out evidence from a traffic stop one year earlier.

On the day in question, officers pulled over an ex-convict on suspicion of speeding and asked for permission to search his vehicle. The man declined, which meant police needed probable cause as required by the Fourth Amendment to proceed. Tank specializes in such matters.

Some officers jokingly refer to their K-9 partners as “probable cause on four legs.” Others describe police dogs as blank permission slips because courts rarely question K-9 reliability. Knowing this, Tank’s handler rushed him to the scene and led him around the vehicle multiple times.

As Jessica Miller reported in The Salt Lake Tribune, police declared that Tank had “alerted” after about three minutes, despite the dog never demonstrating a trained response such as pawing at a particular spot. His natural behavior sufficed to give police permission to search the vehicle.

Once inside, they found a firearm, scale and marijuana residue on an empty pipe. Tank is either incredibly good at his job or a bluffer. A third possibility is that Tank’s handler cued him to alert.

This sometimes happens intentionally, as alleged in a 2012 Nevada case. Officers who filed the lawsuit accused the state of training dogs to respond to signals rather than drugs.

More commonly, cueing happens by accident. Clever Hans, a horse celebrated in the early 1900s for his math ability, shows how this can happen. Close examination revealed the animal was responding to the body language of his oblivious trainer.

Methods exist to check for cueing, but many law enforcement agencies resist scientific rigor in their K-9 programs. The reason relates to incentives.

Dogs respond to cues, and so do humans. Rewards and recognition in police work come from making arrests, which requires evidence that starts with searching. False positives are a feature, not a bug, when every alert opens a door that otherwise would stay closed.

Additional incentives emerge in drug enforcement programs, which tend to turn up large amounts of cash. Tank never could understand why, but humans get excited when they find wads of $100 bills.

All Tank knows is that the paper smells like drugs, something confirmed in multiple studies that show trace amounts of cocaine and other narcotics on two-thirds to 100% of bills in circulation.

Through a scheme called civil forfeiture, law enforcement agencies can seize and permanently keep property, including cash, without ever charging the owner with a crime. These agencies can then use the money to augment their budget. Unintentionally or otherwise, financial motives take over.

Tank found no money at his highly scrutinized traffic stop, but other dogs around the country have scored big. Phil Parhamovich, a musician driving to Salt Lake City in 2017, had his life savings of $91,800 seized after troopers stopped him in Wyoming and brought a K-9 to the scene.

Using an alert from the dog as an excuse, officers took apart the vehicle’s interior. They found no drugs, weapons or contraband, but they did discover cash hidden for safe keeping in a speaker cabinet. Celebrating the discovery, the officers exchanged high-fives. Dogs wag their tails instead, but the responses are similarly cued.

Another motorist in Oklahoma lost $53,000, which included five months of revenue from a Burmese Christian rock band tour and donations to a Thai orphanage. Deputies at the scene said their K-9 gave an alert, but no drugs or paraphernalia were found.

Fortunately, both men partnered with the nonprofit Institute for Justice and got their money back. With each lawsuit, local agencies rolled over almost immediately, knowing they had done something bad.

Studies suggest drug dogs are wrong up to 80% of the time, but unreliable noses are not the problem. The real issue is skewed incentives, especially with civil forfeiture.

Darpana Sheth


Daryl James

Darpana Sheth is a senior attorney and director of Institute for Justice’s National Initiative to End Forfeiture Abuse. Daryl James is an Institute for Justice writer.