Every two minutes, we shed enough skin cells to
cover nearly an entire football field. With a single sneeze, we can spew 3,000
cell-containing droplets into the world. And, on average, we leave behind between
40 and 100 hairs per day. As long as we
live in the world and leave our homes each day, we can’t avoid leaving a trail
of our DNA in our wake.
Every strand of DNA holds a treasure trove of deeply personal information, from our propensity for
medical conditions to our ancestry to our biological family relationships. And
increasingly, police are accessing and testing the DNA contained in our unavoidably
shed genetic material without judicial oversight. That’s why we’re asking
a court to require police to get a warrant before
collecting the DNA we unavoidably leave behind.
Warrantless
access to unavoidably shed DNA is just one part of a troubling trend in police
investigations involving DNA. Already, in more than 60 criminal cases across
the country over the last two years, police have uploaded DNA evidence found at a crime scene to enormous
consumer genetic databases — such as GEDmatch and FamilyTreeDNA — in order to search
for family members of a possible suspect. The databases often return likely relatives
as distant as the suspect’s third cousins. Using this list of likely relatives,
police start building out massive family trees based on marriage certificates,
death records, and more.
Police then
pare the tree down, usually by age and location, in order to identify a likely
suspect (or several). Finally, police follow the suspects around until those
individuals discard items containing their DNA — anything from a Baskin-Robbins spoon to a napkin to a colostomy bag adhesive patch. Without getting a warrant from a
judge, police extract and test the DNA on those items, and use the resulting
genetic profile to determine whether that suspect’s DNA matches the original crime
scene evidence.
This
practice raises profound civil liberties and privacy concerns. Law enforcement
is searching through databases of thousands upon thousands of people’s highly revealing
DNA profiles, and then surreptitiously collecting and testing people’s DNA
without the protections and constraints of a warrant.
In a
friend-of-the-court brief we filed this week together with the ACLU of South
Dakota and the Electronic Frontier Foundation, we argue that law enforcement
must first get a warrant before extracting and analyzing unavoidably shed DNA. The
genetic blueprint we inadvertently leave behind as we discard coffee cups, toss
crumpled tissues, spit out gum, or even lose hair is entitled to the full
protection of the Fourth Amendment.
In the case at hand, State v. Bentaas, a South Dakota state
criminal case, South
Dakota police sent a DNA sample to Parabon Labs, which created a genetic
profile and then ran it against GEDMatch’s database of over one million genetic
profiles. The lab uncovered a few family names in South Dakota’s Sioux Falls
and Hutchinson County areas and identified possible third cousins. Using this
information, South Dakota detectives embarked on their own research to build
out a family tree. Eventually, based on these findings, investigators
identified the defendant, Ms. Bentaas, as a possible suspect.
Without first obtaining a warrant, investigators went to Ms. Bentaas’s residence and took garbage left outside for the trash collector. From the trash bag, police retrieved cigarette butts, cotton swabs, Kleenex with hair, earplugs, water bottles, glass bottles, beer cans, and dental floss. The government then extracted and analyzed the DNA found on these items. Based on the results, investigators arrested Ms. Bentaas.
To defend
its warrantless search and seizure, the state is asserting that people do not
have a reasonable expectation of privacy in their trash, and, therefore, people
also do not have a privacy interest in the DNA they leave on discarded items.
The government’s argument relies on a decades-old, flawed precedent holding that
when we leave our garbage on the curb to be collected, we relinquish our Fourth
Amendment privacy rights in the items contained in our opaque trash bags.
Whatever
the merits of that rule as applied to physical items in the trash, it should
not be stretched to permit warrantless searches of DNA. As the Supreme Court
recently made clear in Carpenter
v. United States, a case argued by the ACLU, old
rules permitting warrantless searches cannot be automatically extended to new
police capabilities made possible by modern technologies. The scope and types
of information that might be discovered through a search of one’s physical
trash pale in comparison to the deeply sensitive and highly personal
information our genetic blueprints can reveal. And though people might
sometimes be able to avoid discarding certain physical items, they cannot avoid
shedding DNA on virtually every surface and object they touch. Our DNA requires
greater protections under the Fourth Amendment.
The
implications of the government’s argument are chilling. If police are allowed
to surreptitiously extract and sequence our DNA without a warrant anytime they wish,
there is little stopping them from grabbing every person’s trash, secretly
extracting our DNA from it, and building a massive database containing our most
sensitive genetic information. Already, local law enforcement officers have
tried to track anti-pipeline protesters by swabbing cigarette butts left behind at protest
sites.
As our
ability to decode DNA improves, the scope of sensitive, private information
that is discernable will only increase. As it does, so will the need for strong
Fourth Amendment protections to keep this information safe from warrantless
searches and unconstitutional intrusion.