“Consider this: None of the challenges I just mentioned is ‘systemic.’ What I mean is that, over time, research has been (and will keep) overcoming each and all of them,” he said in an email. Social networks are growing their databases of people’s faces everyday, and algorithms are getting better at distinguishing between similar faces. Computing, too, seems to forever be getting cheaper.

In other words, no huge technological advance needs to happen for facial recognition to get much better. Acquisti said that a breakthrough would likely occur when facial-recognition technology could be combined with other social-network-provided metadata, such as location, gender, height, and IP address. That would reduce the scope of the task, changing it from ‘identify this random stranger’ to ‘identify this skinny, 5′11″ man on this street in this U.S. city around this time of day.’

“From a technological perspective, the ability to successfully conduct mass-scale facial recognition in the wild seems inevitable,” Acquisti told me. “Whether as a society we will accept that technology, however, is another story.”

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“Let’s say someone is walking down the street,” said Alvaro Bedoya, the executive director of the Georgetown Center on Privacy and Technology and one of the consumer-privacy leaders in the talks. “Shouldn’t a company that has no relationship with that person have to ask for that person’s consent before identifying them?”

This, Bedoya said, is what negotiators were arguing about when consumer advocates decided to abandon the government-hosted talks. Though the talks were rarely productive, he said, it was industry unwillingness to admit that consent was possibly needed even in this one specific case that led consumer advocates to walk out. Bedoya had helped arrange and push for the NTIA talks when he served as chief legal counsel to Senator Al Franken.

A spokeswoman for NTIA told me the agency is “disappointed” the talks fell apart, and that they will continue to hold meetings about the issue. Carl Szabo, a policy counsel at the e-commerce trade association NetChoice, is still participating in those talks on the industry side. He implied that he believed consent would not be needed in many situations.

“You, I, everyone has the right to take photographs in public,” he told Fusion. “Facial recognition can be applied immediately, or days later, or months later. If someone takes a photograph in public, and wants to apply facial recognition, should they really need to get consent in advance? Are they going to chase someone down the street to get them to fill out a form?”

I’m struck by consent being the issue here. Consent as a virtue seems to arise from respect for personal autonomy and, even below that, from the Golden Rule, the moral maxim so universal that almost no ethical tradition omits it. The idea’s also just core to the concept of a contract: Two parties agree about what they will do for each other before they do it.