Facial recognition is becoming more and more common, but ask anyone how to avoid it and they’ll say: easy, just wear a mask. In the future, though, that might not be enough. Facial recognition technology is under development that’s capable of identifying someone even if their face is covered up — and it could mean that staying anonymous in public will be harder than ever before.

The topic was raised this week after research published on the preprint server arXiv describing just such a system was shared in a popular AI newsletter. Using deep learning and a dataset of pictures of people wearing various disguises, researchers were able to train a neural network that could potentially identify masked faces with some reliability. Academic and sociologist Zeynep Tufekci shared the work on Twitter, noting that such technology could become a tool of oppression, with authoritarian states using it to identify anonymous protestors and stifle dissent.

The paper itself needs to be taken with a pinch of salt, though. Its results were far less accurate than industry-level standards (when someone was wearing a cap, sunglasses, and a scarf, for example, the system could only identify them 55 percent of the time); it used a small dataset; and experts in the field have criticized its methodology.

“It doesn’t strike me as a particularly convincing paper,” Patrik Huber, a researcher at the University of Surrey who specializes in face tracking and analysis, told The Verge. He pointed out that the system doesn’t actually match disguised faces to mugshots or portraits, but instead used something called “facial keypoints” (the distances between facial features like eyes, noses, lips, etc) as a proxy for someone’s identity.

But although the paper has its flaws, the challenge of recognizing people when their faces are covered is one that plenty of teams are working on — and making quick progress.

Facebook, for example, has trained neural networks that can recognize people based on characteristics like hair, body shape, and posture. Facial recognition systems that work on portions of the face have also been developed (although, again; not ready for commercial use). And there are other, more exotic methods to identify people. AI-powered gait analysis, for example, can recognize individuals with a high degree of accuracy, and even works with low-resolution footage — the sort you might get from a CCTV camera.

One system for identifying masked individuals developed at the University of Basel in Switzerland recreates a 3D model of the target’s face based on what it can see. Bernhard Egger, one of the scientists behind the work, told The Verge that he expected “lots of development” in this area in the near future, but thought that there would always be ways to fool the machine. “Maybe machines will outperform humans on very specific tasks with partial occlusions,” said Egger. “But, I believe, it will still be possible to not be recognized if you want to avoid this.”

There are ways to trick these systems — wearing a rigid, full-face mask, for example

Wearing a rigid mask that covers the whole face, for example, would give current facial recognition systems nothing to go on. And other researchers have developed patterned glasses that are specially designed to trick and confuse AI facial recognition systems. Getting clear pictures is also difficult. Egger points out that we’re used to facial recognition performing quickly and accurately, but that’s in situations where the subject is compliant — scanning their face with a phone, for example, or at a border checkpoint.

Privacy advocates, though, say even if these systems have flaws, they’re still likely to be embraced by law enforcement. Last month, for example, police in London used real-time facial recognition to scan people attending the annual Notting Hill Carnival. Before the event they assembled a “bespoke dataset” with images of more than 500 people who were either banned from attending or wanted for arrest and then set up cameras at one of the Carnival’s main thoroughfares. According to a report from human rights group Liberty, only one attendee was successfully identified using this system (and even then his arrest warrant was out-of-date) while there were 35 false positives. The police still deemed it a success.

If you combine this attitude with the increasing adoption of police body cameras, the growth of facial recognition databases, and new AI techniques for analyzing data, it seems clear that public anonymity is being undermined. And in the current political climate, where protests are becoming more common and more violent, this is potentially very dangerous. And as Tufekci noted on Twitter, this new technology is often developed without considering the uses it might be put to.

Amarjot Singh, the lead researcher behind the recent paper published on arXiv, said he thought the systems themselves were neutral, and whether they would have a harmful effect on society depended on how they were deployed. “There are more benefits to this technology than harm,” he told The Verge. “Everything can be used in a good way and a negative way. Even a car.” He added that he and his colleagues were working to get funding to improve their system, and that they might eventually commercialize it. “To expand the dataset we might try and make a product out of it,” said Singh. “We’re not very sure of that yet, but we will definitely be expanding the dataset.”