[…] The researchers discovered that even if individual users turned off data tracking and didn’t share their own information, their mobility patterns could still be predicted with surprising accuracy based on data collected from their acquaintances.

“Worse,” says Ghoshal, “almost as much latent information can be extracted from perfect strangers that the individual tends to co-locate with.”

In many (most?) jurisdictions it is illegal to make a recording of a conversation either which you are not party to, or without consent of all parties involved; sometimes with consideration towards whether there was reasonable expectation that the conversation be private. Even when legal, there are often restrictions on how that recording can be used.

The laws aren’t always written specific to audio/video recording (not that always-recording by google/apple/amazon/etc isn’t a problem already…) – how does such surveillance figure in to existing legislation around the world?