The prominent dataset used to train facial recognition systems was found to contain the facial images of nearly 700,000 individuals using photos from Flickr without users' explicit consent, prompting privacy and surveillance fears. 

As many as 700,000 people had their likenesses uploaded from Flickr to the MegaFace dataset, including many children, none of whom had any idea that their images had been used, or provided consent for them to be used. 

Some of these people were unhappy their images had been repurposed in this manner, according to the New York Times. 

The Times also reported that the dataset had been used by companies including Google, Amazon, Ntechlab, Mitsubishi Electric, Tencent, and SenseTime to test or train their facial recognition algorithms to monitor terrorists, protesters and the general public, including Uyghurs in China. 

The finding prompted speculation that companies using the MegaFace dataset may be subject to significant liability litigation, potentially leading to class-action lawsuits, notably under the US state of Illinois' Biometric Information Privacy Act (BIPA).