Jane J. Lee
Anyone who’s been through an airport, crossed national borders, or gone to a public school in the United States has seen detection dogs, noses diligently sniffing for illegal drugs or banned produce and invasive insects.
There are even dogs trained to detect wildlife or wildlife parts, like rhino horns and ivory, that smugglers try to sneak across borders. Just last week, the U.S Fish and Wildlife Service graduated their first class of dogs—four retrievers—trained to sniff out illegal wildlife.
But what happens when one of those drugs, fruits, or animals is taken off the list of contraband? The question has gotten new currency since Washington state and Colorado legalized marijuana through voter-approved referendums last fall.
At least 16 other states, meanwhile, have some form of legalized or decriminalized marijuana, whether for medical or recreational uses. And other states are taking steps toward legalization.
Some police departments in Washington have already announced plans to retrain their canines to stop indicating when they smell the plant. Other states may soon find themselves having to follow suit.
Mary Cablk, a scientist at the Desert Research Institute (DRI) in Reno, Nevada, who studies dog-handler teams, says that dogs can be reeducated so that they don’t sit, lie down, or bark when they detect an odor they’ve been trained to recognize.
But while it’s relatively simple to retrain a dog not to alert a handler to the presence of marijuana, legal questions about the searches—as well as concerns about the training and evaluation of detection dogs—make detection canines a more complicated breed.
Sticky Legal Questions
The problem with retraining dogs to stop indicating when they’ve scented marijuana is that drug loads can be mixed, said Jason Landrum, a training supervisor at the U.S. Customs and Border Protection’s (CBP) Canine Center in El Paso, Texas.
“What if it’s marijuana and cocaine?” he said. How do you know which substance the dog is alerting on for its handler?
That uncertainty can lead to sticky legal questions, said Larry Myers, an associate professor and veterinarian at Auburn University in Alabama, who provides expert testimony on cases involving detection dogs. “And that’s where defense attorneys are going to have a blast in Washington [state].”
Lawyers could argue that even though a dog was retrained to no longer alert on marijuana, there wasn’t adequate evidence to confirm that reeducation, he said.
It’s also unclear whether every Washington police department intends to retrain their detection dogs. A canine that hasn’t been retrained might alert an officer to a substance legal under state law, leading to a search when the police had no cause to detain someone based on that alert.
Retraining a dog to stop alerting on a particular scent, such as marijuana, is fairly straightforward, Cablk said. If a trainer stops rewarding a dog for alerting a handler to the presence of a particular scent, then the alert behavior can be unlearned.
But even if dogs are trained to stop telling humans about the presence of marijuana, “they’re absolutely [still] going to smell it,” she said.
“Detection is a physiological phenomenon,” Cablk said. “[Dogs are] constantly detecting things,” and they don’t have control over that any more than we have control over seeing what’s in front of us if our eyes are open, she explained.
A strong drive to follow airborne scents is one of the characteristics that the CBP looks for in detection dog candidates, said Landrum.
Once dogs with a strong scent drive are found, the CBP screens them for potential medical issues. If they clear their physicals, Landrum said, the dogs begin their training.
Trainers scent one toy with four target odors, such as marijuana, cocaine, methamphetamines, and heroin, and teach the dogs to find the toy.
The dogs learn to sit when they discover a target odor, and once they have learned a set of smells, they practice finding each odor separately.
The canines also get experience searching in different environments—like open brush, forested areas, or airports—that they’re likely to encounter in their seven-year-plus careers, Landrum said.
After six weeks, a dog is paired with the law enforcement officer who will work with it in the field—its handler—and the dog-handler teams then undergo another six weeks of training together.
Customs and Border Protection’s Landrum saw firsthand how effective these teams were in apprehending illegal aliens and smuggled narcotics when he was stationed at a checkpoint near Falfurrias, Texas (map), 70 miles (113 kilometers) north of the Rio Grande River.
“That checkpoint consistently led the nation in the amount of seizures it was making,” he said.
A ruling last month by the U.S. Supreme Court—which struck down the use of drug detection dogs to gather evidence around a person’s home without a warrant—compared the canines and their keen sense of smell to a “specialized device” like high-powered binoculars or heat-detection technology.
Room for Improvement
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