An illustration of a driver's license.

When you stand in line to have your photo taken for a driver’s license, you may be unwittingly signing up to join a database of images harnessed for facial recognition scans by the federal government.

Privacy advocates have complained about the practice, which has become a routine part of law enforcement, for years. But now government emails and other internal documents obtained by the Center on Privacy & Technology at Georgetown Law are calling new attention to how states have shared millions of photos with federal officials, including Immigration and Customs Enforcement and the Federal Bureau of Investigation, according to a report in the Washington Post.

In 2016, the Center on Privacy & Technology reported that about half of all American adult faces already appeared in police facial recognition databases. But Jameson Spivack, policy associate at the center, tells CR that those numbers may be higher now.

Photos are included even if the ID owner has never been accused of a crime.

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The FBI has been using Department of Motor Vehicles photos since at least 2011, according to privacy advocates. The databases are of interest to ICE because a number of states allow residents to obtain driver’s licenses regardless of their immigration status.

At a congressional hearing last month, Kimberly J. Del Greco, FBI deputy assistant director, testified that facial recognition technology is necessary “to preserve our nation’s freedoms, ensure our liberties are protected, and preserve our security.”

However, the use of DMV photos for law enforcement has vocal opponents. “[It] raises both privacy and civil liberties concerns,” says Sharon Bradford Franklin, director of surveillance and cybersecurity policy at the New America Open Technology Institute, a think tank based in Washington, D.C. “Just because one government agency obtains sensitive personal information legally for a specific reason doesn’t mean that any other government agency should have access to that data for a range of other purposes, including possible criminal prosecution.”

Here’s what you need to know.

Is This the Same as Face ID in an iPhone?

Facial recognition is already a part of many people’s lives. You may be using it dozens of times a day to unlock your smartphone. But there are important differences between the face scans that open iPhones and the methods employed by law enforcement.

“What we do on a phone is authentication,” says Anil Jain, a professor of computer science at Michigan State University who studies computer vision. “We are simply comparing two face images. But when law enforcement is searching for a person of interest, the system has to search against a large database of millions or even a hundred million photos. The accuracy of facial recognition goes down as the size of a database increases.”

Other factors can impair accuracy, too, including the age of the photos and the fact that law enforcement is often comparing photos in a database to low-quality surveillance footage.

In addition, studies have shown that facial recognition technology is far better at identifying white men than members of other groups, which can lead to mistaken arrests.

“The technology disproportionately impacts groups that are already marginalized, particularly women and individuals with darker skin,” says Jeramie Scott, senior counsel at the Electronic Privacy Information Center and director of the EPIC Domestic Surveillance Project.

Is the FBI Looking at Your DMV Photo?

Twenty-one states currently allow federal agencies such as the FBI to run searches of driver’s license and identification photo databases.

“If you live in one of these states and have a driver’s license, you are in one of the databases that the FBI has access to,” says Georgetown’s Spivack. “From state, local, and federal databases, the FBI alone has access to 641 million face photos, according to the Government Accountability Office. ICE has run searches of driver’s license photo databases in three states: Utah, Vermont, and Washington.”

To see a list of the states that are involved, see page 5 of the GAO’s Report [PDF].

Even if your state doesn’t grant law enforcement agencies access to ID photos, your image may still be swept up in other facial recognition programs. For instance, the Department of Homeland Security uses passport photos for its facial recognition systems.

“The thing about facial recognition is that it’s a covert operation,” Jain says. “A photo can be captured and used without your knowledge.”

Private companies often use consumers’ photos for facial recognition, as well. For example, Facebook uses facial recognition to identify users in photographs uploaded by their friends.

Is This All Legal?

No federal laws specifically address the use of facial recognition, and the Supreme Court has never weighed in on whether the Fourth Amendment’s prohibition of unreasonable searches and seizures applies to the technology.

Politicians on both sides of the aisle have called for greater federal oversight of law enforcement agencies’ use of facial recognition.

Meanwhile, San Francisco and the Boston suburb of Somerville, Mass., recently passed laws that ban local police from using facial recognition, and state legislation has been proposed in Massachusetts.

“This is yet another area where the technology is developing much more quickly than the law,” New America’s Franklin says.