In today's second Supreme Court case involving police dogs, Florida v. Harris, the justices seemed much more inclined during oral arguments to side with the government. Unlike in Florida v. Jardines, where Antonin Scalia joined some of the more left-leaning justices in questioning the constitutionality of bringing a drug-detecting canine to a suspect's doorstep without a warrant, even the liberals were wary of establishing rules for assessing the reliability of a dog's signal as grounds for a search, while Scalia was transparently hostile to the idea.

The argument offered by Gregory Garre, the lawyer representing Florida in this case as well as Jardines, was pretty straightforward: Trust us. "The handlers themselves are going to be in the best position to know the dogs and evaluate their reliability," he said, "and they have a strong incentive to ensure the dogs are reliable." So if a cop trying to justify a search vouches for the reliability of a dog whose alert supposedly justifies that search, why should anyone question him?

Garre argued that "the most important thing" in judging a dog's reliability "is successful completion of proficiency testing." How does a judge know a dog has successfully completed proficiency testing? Because the police say so. When training is done by "actual police departments," Garre said, "this Court ordinarily would presume regularity." And what constitutes "regularity," especially in a state that, like Florida, has no uniform standards for training dogs or their handlers? "We would ask whether or not the dog successfully completed training by a bona fide organization," Garre said. "We don't think it's an appropriate role for the Court to delve into the contours of the training….You would have to accept it…on its face."

And why wouldn't you? After all, Scalia observed, "if the reasonableness of a search depended upon some evidence given by a medical doctor, the court would not go back and examine how well that doctor was trained at Harvard Medical School." Then again, Harvard Medical School, unlike a police department's dog training program, is accredited, based on uniform national criteria, by the American Association of Medical Colleges, and its graduates must satisfy objective, transparent tests to be licensed and certified in their specialties. Plus, unlike police dogs, doctors can talk, which means they can testify and be cross-examined regarding their qualifications and the reasons for their conclusions.

Scalia seemed genuinely flabbergasted not only by the idea that a dog might be inadequately trained but also by the suggestion that police might exaggerate a dog's reliability. "Why would a police department want to use an incompetent dog?" he asked Glen Gifford, the assistant public defender urging him to agree with the Florida Supreme Court that merely asserting a dog has been trained is not enough to establish its reliability. "What incentive is there for a police department?" Gifford patiently explained that "the incentive is to acquire probable cause to search when it wouldn't otherwise be available." Scalia deemed that suggestion patently absurd:

Officers just like to search. They don't particularly want to search where they're likely to find something. They just like to search. So let's get dogs that, you know, smell drugs when there are no drugs. You really think that that's what's going on here?…They like to search where they're likely to find something, and that only exists when the dog is well trained.

Bear with me, Justice Scalia, and imagine a scenario along these lines: A cop pulls over a pickup truck, ostensibly because of an expired tag but maybe because something about the driver strikes him as suspicious. The guy seems nervous, squirrely, and restless, and the cop thinks: I bet he's a tweaker. After the driver refuses consent to a search, the cop, who just happens to have a drug-sniffing German shepherd with him while keeping his eye out for expired vehicle registrations, walks the dog—let's call him Aldo—around the truck. Although no one else (certainly not Aldo) can testify to this, the cop claims the dog alerted to the driver's side door handle by getting excited and sitting down. The cop searches the truck but does not find any substance that Aldo is trained to detect. He does find hundreds of pseudoepedrine pills, along with other ingredients for making methamphetamine. About two months later—weird coincidence!—the same cop stops the same guy in the same pickup truck, this time ostensibly because of a busted brake light. Aldo supposedly alerts again at the same spot, but again there are no illegal drugs in the truck. The cop suggests that both unverified alerts were due to meth residue from the driver's hand, which might be true. Alternatively, the dog may have been distracted by other smells, or he may have alerted in response to subconscious signals from a handler keen to confirm his suspicions. Maybe the cop, due to said suspicions, misinterpreted the dog's behavior. There are other possible explanations as well.

This scenario may sound familiar, Justice Scalia, because it is exactly what happened in the case you are currently considering. Can you discern any possible incentives here for misrepresenting a dog's reliability, or even for valuing a dog who will alert on cue, subconscious or not? I can, but I am not as mesmerized as you are by the "new professionalism" of America's police officers.

One justice, Sonia Sotomayor, did express concerns about the high error rates of some police dogs and how they might affect probable cause for searches of not just vehicles but also homes (the issue in Jardines). "Who determines when a dog's reliability in alerting has reached a critical failure number?" she asked. "I'm deeply troubled by a dog that [accurately] alerts only 12 percent of the time….That seems like less than probability." Garre refused to be pinned down on that question, saying "this Court has rejected a numerical conception of probable cause." Gifford made the same observation but added that "in the lower courts, once you get below 50 percent, probable cause is much less likely to be found." That seems about right to me. Contrary to what Garre claimed, the Florida Supreme Court is not demanding that drug-detecting dogs be "virtually infallible." But is it too much to ask that they be right at least half the time?

The full transcript of the oral arguments is here.