But new research underway is taking on the fingerprint match probability problem. And preliminary results published in February in Significance, the magazine of the American Statistical Association and the UK’s Royal Statistical Society, give a taste of what may one day be a new fingerprint evidence reality. The researchers’ report announced the creation of a statistical model that will allow fingerprint evidence to be quantified so it can be accorded appropriate weight in courtrooms.

Cedric Neumann, Pennsylvania State University assistant professor of forensic science and statistics, is its lead author. “It is unthinkable that such valuable evidence should not be reported, effectively hidden from courts on a regular basis,” he said in a statement. “Such is the importance of this wealth of data, we have devised a reliable statistical model to enable the courts to evaluate fingerprint evidence within a framework similar to that which underpins DNA evidence.”

Neumann is not suggesting anything close to overnight change here. The goals are long term and much testing remains to be done, both of the model itself and if that passes muster, of the legal system’s reaction to it. Courtroom battles surrounded DNA in its infancy and are certain to converge on any attempts to introduce a statistical approach to fingerprint evidence.

“It remains to be seen how future legal battles play out,” Neumann and his fellow researchers wrote, “but we see models such as this one as a powerful platform for change.” The full study is due to be published later this year.

Meanwhile, the FBI’s fingerprint database, the Integrated Automated Fingerprint Identification System, grows by thousands daily, with more than 70 million subjects’ prints in its criminal master file alone. Some experts, like Mnookin and cognitive neuroscientist Itiel Dror, ask if the database’s very size may make accidental matches more likely.

As Dror said in 2009, “It enables you to look at millions of prints very quickly, make quite good comparisons; it enables you to resolve cold cases and is very good in many ways. However, that same powerful technology that helps solve crimes has also increased the likelihood of finding very similar fingerprints by accidental coincidence.”

In February, the National Institute of Standards and Technology and the Department of Justice’s National Institute of Justice issued a report—three years in the making—on improving fingerprint analysis. After examining all manner of factors that can impact the process, the 34-people strong Expert Working Group on Human Factors in Latent Print Analysis offered 34 recommendations, including “Urging management at forensic science provider facilities to foster a culture in which it is understood that some human error is inevitable and that openness about errors leads to improvements in practice.”

In February 2009, the day after the release of the National Academies of Science’s sweeping report on forensics, Robert J. Garrett, then-president of the International Association for Identification, also sounded a cautionary note (pdf). “It is suggested,” he wrote, “that members not assert 100% infallibility (zero error rate) when addressing the reliability of fingerprint comparisons.”

Researchers Mark Pagea, Jane Taylor and Matt Blenkins, in their March 2011 paper Uniqueness in the Forensic Identification Sciences – Fact or Fiction, contend that “the forensic examiner should therefore not use terms such as ‘unique’ or even ‘individualization’ as they are not the issues the forensic practitioners should concern themselves with; these are issues for the judge and jury. To claim that a fingerprint or bitemark has identified someone ‘to the exclusion of all others,’ or has been ‘individualized’ to only this person, usurps the jury’s role as the rightful assessor of the evidence…”

“It’s a match!” claims also have been notoriously derailed in a couple of high-profile cases. In March, a report finally vindicated Scottish police officer Shirley McKie, who was accused of leaving a fingerprint in the home of a female murder victim. Officer McKie canvassed neighbors in the case but always swore that she never entered the victim’s home – the crime scene.

In the most notorious mistaken print case of all, Oregon resident Brandon Mayfield was erroneously fingered by several top FBI analysts as the Madrid train bomber. Fortunately for Mayfield, Spanish authorities tied the prints to their correct owner, Ouhnane Daoud. Ultimately, the FBI was compelled to admit that its bias and “circular reasoning” had led it to target an innocent man.

But the relevance and importance of probability research becomes clear when you consider that the reason such similar prints were located in the first place was as a result of the FBI database’s power to search through tens of millions of images. Reason enough for a vocabulary rethink.