You might not realize it’s happening, and you definitely might not realize you have the right to object. But when you enter an airport in 2019, it’s possible that your airline—or the federal government—are scanning images of your face for their security-related purposes.

Say No to Airport Facial Recognition

This facial-recognition technology can be used during check-in, baggage drop, security and boarding. For the most part so far, it’s mostly only been deployed for international flights, to confirm passenger identity at the behest of Customs and Border Protection. But airlines and the Transportation Security Administration are considering doing so for domestic flights, as well.

You don’t necessarily get advanced notice that it’s happening, and various airlines—or even different parts of the airport—might give this notice differently. It could range from announcements, to a sign at the gate counter, to check-in reminder e-mails, to on-screen notifications at self-service kiosks.

You can probably count on the fact that your face is being scanned if you’re asked to look into a camera during your journey through the airport. And if you’re asked to remove your hat or sunglasses—which could reduce the effectiveness of the image—that’s another warning sign.

If you’re a U.S. citizen, you have the right to opt out of facial scanning. The Department of Homeland Security has told Congress this on numerous occasions. The website of Customs and Border Protection says so explicitly—but in the fine print—in the “Privacy” section on this page. The Transportation Security Administration confirms the process is voluntary on its website.

It’s worth noting that if you do opt out of facial recognition scanning, authorities will manually inspect your travel documents. And that might mean standing in another line, which could be moving more slowly. In fact, speed and convenience are among the features that CPB and TSA tout in encouraging citizens to go the facial scanning route.

Non-citizens don’t necessarily have the option to just say no—it depends on the airline. Some allow people with foreign passports to join the “opt out” line, but some do not, and it’s possible that in the future, the government will decide that non-citizens must be facially scanned. It could even be the case that citizens will need to do so, although that seems farther off and less likely. It’s also possible that airports could use facial scans for mass surveillance, instead of just individual check-in.

For now, if you want to find out whether your airline has flown this route, you can check on the website, which went live in early June. The site has been put together by a coalition of digital rights advocacy organizations, including a group called Fight for the Future.

But for now, it doesn’t sound as if very many passengers are fighting against facial recognition—either that, or they’re not even aware of it’s happening. According to Delta Airlines, which uses biometric screening at Terminal F in Hartsfield-Jackson Atlanta International Airport, fewer than 2 percent of passengers choose to join the opt-out line.