Police departments across the country are using facial recognition technology to identify protesters they say are breaking the law. NBC News' Jacob Ward explains how it works.Oct.

Protesters regularly wear disguises like bandanas and sunglasses to prevent being identified, either by law enforcement or internet sleuths. Their efforts may be no match for artificial intelligence, however. A new paper to be presented at the IEEE International Conference on Computer Vision Workshops (ICCVW) introduces a deep-learning algorithm--a subset of machine learning used to detect and model patterns in large heaps of data--that can identify an individual even when part of their face is obscured. The system was able to correctly identify a person concealed by a scarf 67 percent of the time when they were photographed against a "complex" background, which better resembles real-world conditions. The deep-learning algorithm works in a novel way.