Just more than a month ago, privacy advocates celebrated a win when a federal judge ruled that border agents need reasonable suspicion before they can search a person’s device at U.S. entry points. But excitement for traveling privacy is quickly dissipating as the Trump administration intends to implement a different kind of personal invasion: a facial scan requirement for all travelers entering or leaving the country.

The Department of Homeland Security (DHS) is set to officially propose the policy with more details next July. But Reuters reports it would require all international travelers, U.S. citizens or not, to be photographed if they want to pass through the American border.

People should be able to move freely without being forced to surrender to an invasive biometric facial scan every time they travel internationally. They already have to prove their citizenship with a passport when traveling abroad. Adding the additional facial scan requirement is an unnecessary breach of every traveler’s personal privacy.

The government can already track people’s movement to some extent. But it doesn’t need to document a person’s facial features just because he’s traveling abroad. The Trump administration argues such a mechanism is needed, as it will help the feds “combat the fraudulent use of U.S. travel documents and aid the identification of criminals and suspected terrorists.”

Which criminals they will be tracking and what constitutes a “suspected terrorist” is up for debate. And it’s a sticky one, as the answer could change depending on who’s in power and what biases they have. Either way, mere suspects should not have travel rights preemptively restricted prior to a conviction — especially when the feds have a track record of vague standards and poor judgments when it comes to categorizing people as threats. Innocent until proven guilty.

A picture or video surveillance can automatically identify people, which is why facial scans are so attractive to DHS. Some airports already use the technology in partnership with the Customs and Border Protection biometric exit program, wherein travelers can trade their privacy for convenience. But the exit program is different in that it allows people to opt out — just barely.

Facial Scan Technology Is Unreliable and Invasive

One problem with a full-on airport security rollout is the unattainable goal of better identifying people with facial scans. The current error-prone facial recognition technology is not ready for security reliance. The technology is far from accurate, and when tested in California, it misidentified 26 legislators as criminals — that’s 1 in 5 people.

While that may be a laughable example, it’s pertinent that these mistakes are not fully considered in the implementation and use of the technology, especially when a person’s privacy and ability to freely travel is on the line. It’s unclear how airports that use facial scans handle this problem.

The current algorithms are particularly inaccurate in identifying women and nonwhite people. Tom Simonite of Wired reported that even the best facial recognition technology misidentifies black people five to 10 times more than it does white people. It also performs lower when identifying women in comparison to men. This is one of the many reasons some states, such as Oregon, New Hampshire, and California, have banned police from using the technology with their body cameras.

Even if the technology had a 100 percent accuracy rate, facial scans for identification simply aren’t needed. DHS already has complex systems for detecting people. All major U.S. ports of entry collect international travelers’ fingerprints — a form of identification that is more accurate in identifying people than facial scans have proved to be. They also photograph foreign travelers entering the country.

But DHS has not provided a sound reason why fingerprints are now inadequate, and facial scans should be expanded for all people. Domestic terrorists are a far greater threat than foreign terrorists to the safety of Americans today. So if the goal is to protect the public from terrorism, it makes no sense to focus surveillance efforts on international travelers.

To fly in and out of the United States in a post-9/11 world, one must have proper government-issued documentation. These documents must be thoroughly checked by federal agents upon entering the airport gate, and every person is subject to have all her belongings scanned and searched. They must also comply with a full-body scan, fingerprint swabs, bodily pat downs, and sometimes strip searches.

That’s allegedly not enough intrusion into travelers’ lives in the government’s eternal quest to capture potential threats. Now the feds want to run everyone’s facial scan through a database to determine just exactly who they are.

If facial recognition technology is implemented at airports, its uses will extend far beyond identification. For example, some countries are now using it to detect emotions by tracking people’s facial movements when Border Patrol agents ask them questions. Certain tics are supposed to determine whether a person is lying. But the reliability of emotional detection technology is unfounded, according to an academic study commissioned by the Association of Psychological Science. Relying on yet another flawed technology is yet another bad move.

The Cost of Facial Recognition Is Individual Privacy

Every time we give an inch of freedom, not only is it impossible to gain back, but that inch gradually expands to two, then three, and never stops growing. Proponents of small government should be familiar with this problem, inherent across government agencies nationwide. Privacy rights are no different.

If Americans get used to the idea of government scanning their faces, despite its potentially limited use to international travel now, facial recognition will eventually become more prevalent in the future. Once authorities use it in airports, it logically follows they will employ the technology in domestic travel. It will likely expand beyond flights and into other modes of public transit such as buses or trains, and even in public areas such as parks.

It may seem implausible now, but other governments have already gone far beyond this. The surveillance state is being used to suppress free expression and movement in Hong Kong, a nation once considered one of the freest places on Earth, for example. Biometric facial scanning is already expanding in police departments across the country with very little regulation. As mentioned above, only three states have banned it so far. And the states’ agencies that use it do so with little governance.

The idea of heightened security sounds great in theory, but it often comes at the cost of relinquishing individual privacy. In a nation with an incredibly low risk for international terrorism, facial recognition is an unnecessary tool. There’s no clear gain in using facial scans for travelers, but the privacy consequences are real. The threat to individual privacy is a right under constant attack — something that important may not be realized until it’s gone.