The Golden State Killer, who terrorized Californians from Sacramento to Orange County over the course of a decade, committed his last known murder in 1986, the same year that DNA profiling was used in a criminal investigation for the first time. In that early case, officers convinced thousands of men to voluntarily turn over blood samples, building a genetic dragnet to search for a killer in their midst. The murderer was eventually identified by his attempts to avoid giving up his DNA. In contrast, suspected Golden State Killer Joseph James DeAngelo, who was apprehended just last week, was found through other people’s DNA — samples taken from the crime scenes were matched to the profiles his distant relatives had uploaded to a publicly accessible genealogy website.
You can see the rise of a modern privacy conundrum in the 32 years between the first DNA case and DeAngelo’s arrest. Digital privacy experts say that the way DeAngelo was found has implications reaching far beyond genetics, and the risks of exposure apply to everyone — not just alleged serial killers. We’re used to thinking about privacy breaches as what happens when we give data about ourselves to a third party, and that data is then stolen from or abused by that third party. It’s bad, sure. But we could have prevented it if we’d only made better choices.
Increasingly, though, individuals need to worry about another kind of privacy violation. I think of it as a modern tweak on the tragedy of the commons — call it “privacy of the commons.” It’s what happens when one person’s voluntary disclosure of personal information exposes the personal information of others who had no say in the matter. Your choices didn’t cause the breach. Your choices can’t prevent it, either. Welcome to a world where you can’t opt out of sharing, even if you didn’t opt in.
Yonatan Zunger, a former Google privacy engineer, noted we’ve known for a long time that one person’s personal information is never just their own to share. It’s the idea behind the old proverb, “Three may keep a secret if two of them are dead.” And as far back as the 1960s, said Jennifer Lynch, senior staff attorney for the Electronic Frontier Foundation, phone companies could help law enforcement collect a list of all the numbers one phone line called and how long the calls lasted. The phone records may help convict a guilty party, but they also likely call police attention to the phone numbers, identities and habits of people who may not have anything to do with the crime being investigated.
But the digital economy has changed things, making the privacy of the commons easier to exploit and creating stronger incentives to do so.