Think about everything else you left behind at the table the last time you went to a restaurant. Well, a good tip, hopefully. Maybe that horrid scarf your aunt gave you for Christmas.
But you also left behind telltale pieces of yourself: a strand of hair on the tablecloth, skin flakes on the arm rest of your chair, and saliva on your fork. In other words, you left enough DNA for anyone to find out more about your genetic identity than you probably know yourself.
Until recently that's never been a big deal. But in the 21st century, with its quickly improving and steadily cheaper genetic technology and ever-shrinking private lives, DNA theft is poised to become a more and more pressing issue—and restaurants are likely to be one of the front lines of that battle.
"This is an area where the law hasn't really caught up with reality," says Andrea Roth, assistant professor at Berkeley Law at the University of California, Berkeley, and a lecturer on DNA-based forensic science. "I don't think people realize what the implications are."
Or think of it this way, says University of California Davis School of Law professor Elizabeth Joh, who's proposed laws against DNA theft: Do you have anything to hide? Then this is an issue you should start thinking about.
"I don't know that every single person at the present moment needs to worry, but if there's any possibility you've committed a crime that would be worth police investigating your DNA, or if you're related to someone who may be the subject of an investigation, if you're a famous person, if you've done something that could make you the target of revenge or blackmail, or if you have a secret of some sort that someone could exploit, you might be worried," she says.
If you're a criminal who wants to eat out while you're on the lam, though, you're out of luck. American courts have almost unanimously treated the DNA you leave behind on coffee cups or dinner plates as fair game for cops without a warrant, even if you're eating at a privately owned restaurant. Under most courts' legal reasoning, you've essentially abandoned your DNA at the table, just as police are allowed to use what's in your garbage can against you without a warrant because you've legally abandoned that trash as well.
In the most high-profile criminal case involving genetic evidence surreptitiously obtained from a restaurant, in Los Angeles in 2010, an officer disguised as a pizzeria waiter took the utensils, plate, and pizza crusts a regular patron left behind to a police lab. From the DNA in the saliva on the crust, detectives identified the customer as the Grim Sleeper, a serial killer who terrorized women in southern California from 1985 to 2007. (Lonnie David Franklin Jr. is awaiting trial for ten counts of murders, but authorities suspect he may be linked to hundreds more.) And that's just one case involving cops using DNA left behind by diners—police are now well aware that restaurants are the one place they can be almost 100-percent sure to get usable genetic evidence for their cases, says David Kaye, associate dean and professor at Penn State Law School and the author of a blog on the legal issues surrounding modern forensic science.
"Restaurants are a popular place that police have used in a number of cases to obtain DNA without the suspects' knowledge," Kaye says. "No one means to leave a trace of their DNA on their pizza crusts, but when it comes to [what legal experts term] shed or 'out-of-body' DNA sampling, the courts always agree that there's no issue with the Fourth Amendment [which deals with police search and seizure and personal privacy protections against government intrusion]."
It's not much better if your biggest worry isn't the government but private and nosy citizens getting your DNA from your restaurant leavings. The current laws on the books, at least in the U.S., are at best vague about whether a person has the right to expect that he or she can keep his genetic information private. (Federal law and many states guarantee that employers and insurers can't use non-consensually obtained DNA to fire or not hire someone or reject them for coverage, but state laws rarely go beyond that.)
"Private people aren't covered by the Fourth Amendment, and in most jurisdictions, it's not a legal problem for someone to take your DNA and analyze it without your permission," Joh says. "There are a handful of states where it subjects people to civil liability, but a tiny number of jurisdictions where it's a crime, but it's never more than a misdemeanor. And in all my searches, I've never found someone who's actually been prosecuted for DNA theft. It's a largely symbolic crime."
Not that people, at least famous people, aren't already worried. On his blog, Kaye has discussed the specialized cleaning crews Madonna hires when she's on tour to eliminate any DNA samples she might leave on dresses, eating utensils, or furniture from falling into the hands of obsessed fans. He's also noted that the one of the jobs of the Secret Service detail for President Barack Obama is believed to be collecting any silverware, plates, and linens he uses at foreign dinners and wiping it clean of his DNA before it goes to the dishwashers.
"In the 2016 presidential election, is there going to be some genetic paparazzo who swipes a sample of a candidate's DNA at a restaurant from a cup or plate or spoon, has it analyzed, and publicizes what he finds?" Joh says. "A paranoid but smart campaign manager is going to have those plates and utensils taken away immediately after the photo op."
DNA evidence that private investigators have stolen from people's trash cans have already proven pivotal to especially nasty, high-powered paternity suits, Kaye says. But it simply isn't clear yet how courts will react to, say, a saliva-covered fork that proves a wealthy Hollywood producer is the father of the baby at the center of a multimillion-dollar divorce.
"The law works in its ponderous way," Kaye says. "And so far, these cases haven't been worth the cost of litigation. But sooner or later, really sensitive information is going to emerge, or someone famous is going to want to make a point about paparazzi, and a court will have to make a ruling."
Current laws dealing with obsessive fans, admirers, and haters are still stuck in the last century, when you couldn't order a full DNA profile on someone using a few cells left behind on the rim of a coffee cup, Roth says.
"Stalking laws say you can't follow someone around and be annoying, but, generally, you have to make somebody feel threatened," she says. "The law is not yet equipped to deal with these new realities."
Joh says U.S. legislators need to start thinking about strengthening privacy protections when it comes to DNA, perhaps looking to the strict laws countries like the U.K. have in place.
"This is going to be an increasingly common issue," she says. "Because people have secrets."
She imagines that, until then, enterprising restaurateurs may decide to take advantage of some people's fear of DNA theft by advertising guarantees to their patrons.
"Why not a restaurant—especially one with a big celebrity clientele—that offers a service to 'erase' your DNA traces from your utensils and food as soon as your are finished?" Joh says. "It's the sort of gimmicky gesture that might appeal to the privacy-obsessed."
But Kaye says there simply isn't the "groundswell of public outrage" that's needed for most people to feel reassured that their DNA won't be swiped and used against them when they go out to their favorite eatery—at least yet. Until then, he says, if someone actually is stealing your genetic material from your restaurant forks, straws, and leftovers, you can find some scant solace: "Most of the time, you won't even know about it."