Earlier this week, Facebook launched Moments, a new photo-sharing app that uses facial recognition technology to dig up forgotten snaps of friends from your camera roll. It's a neat trick, but not one that Facebook's European users will be able to try out: the social network has said that Moments won't launch on the continent due to worries that European regulators will object to its use of facial recognition.

"We have to offer an opt-in choice to people."

"Regulators have told us we have to offer an opt-in choice to people to do this," Facebook's head of policy in Europe, Richard Allan, told The Wall Street Journal. "We don’t have an opt-in mechanism so it is turned off until we develop one." Allan adds that there's currently no timeline for Facebook to develop such an option.

European regulators' dislike of facial recognition is well-established, with Facebook previously forced to withdraw the technology for European users on its main site in 2012 after an audit by the Irish Data Protection Commissioner. At the time, Facebook said it hoped to reintroduce the feature "once we have agreed an approach on the best way to notify and educate users," but judging by the roll-out of Moments, it seems that whatever efforts made since then haven't been enough. The social network isn't alone in facing restrictions in this area, though: Google's recently-launched Google Photos app — which uses facial recognition to sort snaps by who's in them — also limits its use of the technology to the US.

At the moment, America seems to be relatively accepting of facial recognition, but as the technology becomes more widespread and more accurate, it's possible that popular opinion will change. Earlier this week, the Electronic Frontier Foundation (a digital rights nonprofit) and eight other privacy advocacy organizations withdrew from talks with US law enforcement aimed at establishing a code of conduct for the use of the technology.

"People should be able to walk down a public street without fear."

"At a base minimum," wrote the groups in a public statement, "people should be able to walk down a public street without fear that companies they’ve never heard of are tracking their every movement — and identifying them by name — using facial recognition technology."

In a blog post, the EFF noted that it was "especially concerned about commercial use of face recognition because of the possibility that the data collected will be shared with law enforcement and the federal government." The organization noted that the FBI's standard warrant requesting data from Facebook asks for copies of all the images the user is tagged in, but that in future, this warrant might instead just request the "underlying face recognition data."