First, here’s some cool new science:

Dogs understand human behavior better than most people believe, according to a new research.

Researchers in Hungary undertook a study to examine how canines are able to sense emotion in human voices. They trained 11 dogs to sit still in a functional magnetic resonance imaging scanner (fMRI). The scientists recorded brain function in the canines as they listened to 200 human and dog sounds, including crying and laughing.

A group of human subjects was then put through a similar experience . . .

“In this first comparative neuroimaging study of a nonprimate and a primate species, we made use of this special combination of shared environment and evolutionary distance,” the Hungarian team wrote in the article detailing the study.

If brains of both species have similar structures, they could handle social clues in much the same way as one another. This could also partly explain the special bond between humans and dogs.

“This method offers a totally new way of investigating neural processing in dogs. At last we begin to understand how our best friend is looking at us and navigating in our social environment,” Attila Andics, of MTA-ELTE Comparative Ethology Research Group in Hungary, wrote in the press release.

Dog lovers often say their canine companions understand feelings and emotions. This study confirms that widely-held belief. It also provides a basis for the understanding.

Law enforcement agencies of course use dogs in a variety of ways. And when dogs are used in ways that don’t put them in a position in which their sense of smell competes with their desire to please their handlers, they perform very well. Dogs that hunt for explosives or land mines, for example, do well because their handlers’ suspicions aren’t a factor. Indeed, the handler’s safety rests on him putting his faith in the dog’s abilities. It’s also in the best interest of the handler, the dog and everyone else involved to be sure that the dogs are trained to compensate for the fact that we’ve bred into domestic dogs a strong desire to please us.

But it’s quite a bit different when we’re talking about dogs that are used to sniff for drugs or to identify suspects in “scent lineups.” Here, a handler may well tip off his dog to alert when the handler suspects a motorist is transporting drugs or may direct the dog to the suspect that he thinks committed the crime. This can be blatant and planned or it can be subtle and unintentional. But the result is the same: Reviews of performance records show that drug dogs have disturbingly high rates of “false alerts,” sometimes with error rates well above 50 percent.

Police will say that “false alerts” aren’t really false at all, that the dog is instead alerting to trace amounts of an illicit drug that had previously been stored in the car. That may or may not be true. One academic study of K9 handler teams found that packages designed to trick dog handlers were much more likely to trigger false alerts than packages designed to trick the dogs. Again, the dogs were reading and reacting to subtle clues from the handlers.

But here’s the problem: Dog trainers I’ve interviewed say drug dogs can be trained to only alert to measurable quantities of a given drug. But police departments don’t want them trained that way. They want dogs that will given the legal authority to conduct a search whenever the handler wants to conduct one. Which is to say they want dogs that will merely confirm the hunches of its handler. (It doesn’t help when they give the dogs names like “Guilty.”) And the problem with that is that the entire reason we have a Fourth Amendment is to prevent the government from subjecting us to searches based on nothing more than the hunch of a government official. Yet the Supreme Court seems fine with all of this.

But as bad as the drug dog problem is, “scent lineups” are even worse. Which brings me to this story:

A Texas woman has sued investigators who used dogs to pick her out of a “scent lineup” — a widely questioned investigative technique that nonetheless put her in prison for six years before her murder conviction was overturned.

The woman, Megan Winfrey, 25, was freed in April after the Texas Court of Criminal Appeals upheld its own ruling acquitting her in the 2004 slaying of a high school custodian.

Her father, Richard Winfrey Sr., and her brother, Richard Winfrey Jr., have also been cleared in the case after trials that all used the same evidence.

In a suit filed this week in U.S. District Court in Houston (PDF), Winfrey accuses San Jacinto County, current and former sheriffs and deputies and the dog trainer of malicious prosecution and civil rights violations.

The suit involves a former Texas police deputy named Keith Pikett, who claimed his dogs had near miraculous powers. For example, in the case of exonoree Anthony Graves, Pikett claimed his dog could detect Graves’s scent on a 17-year-old piece of evidence retrieved from a burned-out crime scene. Graves served time on death row and 18 years in prison before he was released in 2010. Pikett was something of a celebrity in Texas law enforcement. Prosecutors put him on the stand in hundreds of cases. He has since been the subject of a class action lawsuit brought by others wrongly convicted or arrested by his testimony.

But he isn’t the only one. In Florida, at least three people have been exonerated after they were convicted by testimony from the late dog handler John Preston, who claimed his dogs could even track a scent underwater. Questions about Preston in fact go back two decades, including one prosecutor who resigned in protest rather than take part in what he said was “manufacturing evidence.” But prosecutors kept using him, and the courts kept allowing them to. Activists say there are dozens more still in prison. Yet Florida officials and lawmakers haven’t shown much interest in going back to see if some of those people might be innocent, too. (Perhaps they’re too busy trying to find ways to speed up executions.)

Despite the growing piles of evidence that these “scent lineups” are junk science, and that people implicated by them have later been shown to be innocent, the federal courts have still been reluctant to grant new trials based on scent lineup claims without other evidence of innocence. And so far, only some five states have banned or restricted “scent lineup” evidence from the courtroom.