5 Ways Law Enforcement Will Use Tattoo Recognition Technology

There's an action movie cliché in which a cop inspects the body of a felled assassin or foot soldier and discovers a curious tattoo that ultimately leads to a rogue black-ops squadron, a secret religious sect, or an underground drug trafficking ring. 

The trope isn’t entirely Hollywood fantasy, but the reality of emerging tattoo recognition technology is closer to a dystopian tech thriller. Soon, we may see police departments using algorithms to scrape tattoos from surveillance video or cops in the field using mobile apps to analyze tattoos during stops. Depending on the tattoo, such technology could be used to instantly reveal personal information, such as your religious beliefs or political affiliations.

For years, law enforcement has used tattoos to identify criminal suspects as well as unidentified victims. Police have also used tattoos to map out subcultures and networks of gangs and hate groups. Until recently, however, tattoo matching and analysis has involved flipping through the pages of photo binders; any computer-assisted matching has been limited to metadata searches of keywords.

NIST's Official Tattoo Recognition Technology Logo

In 2014 and 2015, federal researchers at the National Institute for Standards and Technology (NIST) joined forces with the FBI to launch a program to accelerate tattoo recognition technology. As part of Tatt-C (the code name for NIST’s "Tattoo Recognition Technology Challenge"), officials assembled a giant dataset of prisoner tattoos and divvied it out to biometric companies, research institutions, and universities. They were asked to run five experiments to show how well their algorithms could match tattoos under various circumstances. 

Some tests involved matching different photos of the same person’s tattoo. Other experiments sought to match similar tattoos on different people based on their characteristics—such as a crucifix, Minnie Mouse, and Chinese calligraphy. These tests pose serious concerns for privacy, free expression, religious freedom, and the right of association.

Each one of these experiments correlated to a specific law enforcement use. The Tatt-C results, released last summer, now serve as a crystal ball into what law enforcement has planned for this technology over the years to come.

Here are the five tests and what they tell use about the future of tattoo recognition technology.

Related: Learn why EFF is calling for an end to this research. 

Note on the data: The Tatt-C dataset contained 15,000 images obtained by the FBI from prisoners. The dataset was split into subsets and sub-subsets for individual trials. Tatt-C participants self-reported their results, which were not independently verified. The percentages below reflect the accuracy within the experiment, and not necessarily how accurate the technology would perform in the real world.

Tattoo Detection: Why would police want algorithms that can detect whether an image has a tattoo or not? 

Any given law enforcement agency may be sitting on an immense, unsorted collection of images. Mugshots, scars, birthmarks, and tattoos—all mixed up together, some unlabeled, some mislabeled. Without computer assistance, it could take significant staff-power to sort through it all. NIST suggests that automated tattoo detection would streamline an agency’s ability to classify images.

Perhaps the more concerning use case for privacy advocates is that tattoo detection technology would also pave the way for algorithms to isolate tattoos from images scraped from the Internet or captured by security cameras.  

The bad news is the technology is already highly sophisticated. 

Tatt-C’s research team reported back that three different organizations’ algorithms could detect a tattoo in an image with more than 90% accuracy.  The private biometric technology company MorphoTrak (a subsidiary of Safran) claimed the best result; their algorithm was able to detect whether an image contained a tattoo or not with 96.3% accuracy.

Tattoo Identification: When we say biometrics, we are talking about unique physical or behavioral characteristics that can be used to identity you. Fingerprinting has been used by criminal justice agencies for over a century to identify suspects; tattoo recognition can be used in much the same way