We all hate long lines, whether we’re at train stations, airports, or grocery stores. Researchers and governments are hard at work to ease frustrating line congestion via facial recognition technology. Facial scanners may reduce time spent standing in boring lines, but they also threaten our privacy, which we shouldn’t sacrifice on the altar of convenience.

In the United States, the Department of Homeland Security (DHS) is taking steps to implement facial scanning systems at airports. Facial scan trials are already underway in six airports, with more deployments planned by early next year at “high-volume”international airports. The scanners are part of a biometric entry-exit plan that aims in part to confirm the identity of travelers leaving the U.S.

Two airlines—Delta and JetBlue—allow travelers to use facial scanners at select airports. From the Associated Press:

DHS officials hope to defray costs through partnerships with airlines that are incorporating biometrics to boost efficiencies. Two airlines in the pilot program—Delta and JetBlue—tout identity-verification technology’s convenience for other ends: Delta for speeding baggage handling, JetBlue for eliminating boarding passes. Both carriers say they will not retain customers’ face scan files.

In their privacy impact assessment for the facial scanning scheme DHS bluntly states, “the only way for an individual to ensure he or she is not subject to collection of biometric information when traveling internationally is to refrain from traveling.” The same assessment also points out that Customs and Border Protection (CBP) can share facial recognition information with state, local, and federal agencies.

Although CBP does mention that all newly captured photos will be deleted after 14 days it’s worth keeping in mind that CBP could extend this time period in the wake of a terrorist attack or other emergency

In the United Kingdom, government-backed facial recognition technologycould be used to ease congestion at London Underground stations. The goal is for participating passengers to simply walk by cameras rather than wait at cumbersome ticket turnstiles. The technology, built by Bristol Robotics Laboratory, is reportedly accurate enough to distinguish between identical twins. According to Bristol Robotics Laboratory’s Professor Lyndon Smith, the technology could be commercially available in 2019.

The United Kingdom is one of the most surveilled countries in the developed world, and the data collected as part of this proposed scheme will be in the hands of Transport for London, a local government body. We shouldn’t be surprised if London Underground’s facial recognition data finds its way into the hands of law enforcement.

Such data sharing between Transport for London and London police would hardly be unprecedented. A 2014 report from London’s Metropolitan Police Service (MPS) stated that Transport for London sends MPS license plate data for national security purposes:

The Mayor’s Crime Manifesto, published in April 2012, made a commitment to make Transport for London Automatic Number Plate Recognition data available to the Metropolitan Police Service for the purposes of preventing and detecting crime.

[Transport for London] collects [Automatic Number Plate Recognition] data from the central London Congestion Charging Zone and the London-wide Low Emission Zone camera networks and processes it for the purpose of enforcement and traffic monitoring. This data is already transferred to the MPS for the purposes of National Security.

In May 2015, the London mayor announced that MPS had access to license plate data for criminal—not only national security—investigations:

The Mayor, Boris Johnson, has more than doubled the number of high-tech cameras used by the Police (MPS) to help identify criminals and bring them to justice. Around 2,300 Automatic Number Plate Recognition (ANPR) cameras are now in use for policing purposes in London after the MPS were granted access to 1,300 Transport for London cameras which were developed to enforce the Congestion Charge Zone and the Low Emission Zone. Each camera takes a digital reading of passing traffic, allowing speedy identification and collecting real-time data on the precise whereabouts of stolen cars or vehicles involved in crime. This vital information enables the police to detect more criminals, and deter and disrupt criminality on London’s streets. The move to incorporate Transport for London’s ANPR cameras into the Met’s network was one of the Mayor’s 2012 Manifesto pledges and part of his drive to bear down on crime in the capital.

A similar access policy will no doubt be in place once the London Underground’s facial recognition system is up and running.

Chinese companies are developing facial recognition technology that can not only identify people but may one day be able to predict crimes. A Singaporean company, Xjera Labs, has built surveillance technology that can identify vehicles as well as people. It also allows users to search CCTV footage for particular activity, such as a street fight. Xjera Labs’ technology is used by police in Singapore as well as Chinese schools. This may strike some as creepy and intrusive, but many people see benefits. Chinese researchers have built ATMs that use facial recognition to determine identity. Thanks to facial recognition, one cafe owned by the Chinese e‑commerce company Alibaba does not need self-checkout kiosks, let alone human check-out assistance.

These innovations from the United Kingdom and China or others like them will find their way to the United States, where around half of adults are already part of a facial recognition network.

Shorter lines, no ticket turnstiles, and stores without checkouts sound great, but they come at a significant cost when they rely on facial recognition.

The increased use of facial recognition will enable law enforcement to more easily track your lawful movements. When merged with CCTV, body camera, and drone technology facial recognition will allow law enforcement to identify law abiding citizens. The widespread use of facial recognition will open the door for increased tracking and surveillance as well as the stifling of First Amendment-protected activities.

We shouldn’t think of facial recognition as a necessarily nefarious technology. It would be great to live in a world where there are fewer airport and shopping lines and our privacy is protected. And we could, provided that lawmakers take steps to limit the facial recognition data government collect and citizens don’t hurry to sacrifice their privacy for convenience.