Human beings leave behind DNA wherever we go. We shed skin. We sneeze out DNA-containing droplets. We shed hairs. We can’t avoid it.
Now, DNA testing has reached the point where the police could start testing this unavoidably-shed DNA and using it in criminal cases. With ancestry DNA, we don’t even have to be the person the police are interested in; any reasonably close relative will do. Some DNA testing allows the identification of a person based on a close relative’s DNA sequence.
But the information contained in our DNA isn’t just an ID tag for the police to use. It contains information about our ancestry and biology, including our propensity to get certain medical conditions. In 2008, Congress passed the Genetic Information Nondiscrimination Act recognizing that some genetic information could easily be used against people. It’s private, and it’s only getting more revealing over time.
When should the police be able to use a person’s DNA without a warrant? It’s potentially the most private and telling information we have about ourselves, so there need to be standards. Should the police be allowed to use the DNA that has been publicly uploaded to databases like GEDmatch and FamilyTreeDNA? Should they be allowed to follow people around and pick up discarded napkins and hairs?
Police are actually doing this
According to the ACLU, it’s becoming more common for law enforcement to do either or both of those things. They often start out with crime scene DNA, which they upload to GEDmatch or the like, looking for matches. The matches can include relatives as distant as third cousins. They can use these matches to build a family tree of the suspect and ultimately identify him or her.
Once they have extrapolated who the suspect might be, they follow that person around and collect items like discarded napkins, hairs or the like for further testing. That way, they can match their original crime scene sample to that of an actual person.
Should the police be allowed to create a genetic dossier on someone based on crime scene DNA? Should they then be allowed to surreptitiously collect DNA samples from suspects without a warrant and the associated legal constraints and judicial oversight?
The ACLU, the Electronic Frontier Foundation and other groups have filed amicus briefs in a recent South Dakota case where police used just this method to identify a suspect. They developed a dossier based on third cousins, then took garbage from a man’s house to confirm he was the suspect.
Do we lack any privacy interest in our shed DNA? If not, what can still be considered private?