Do People Under Arrest Have a Privacy Right in Their DNA? The U.S. Supreme Court Hears Argument in Maryland v. King Part Two in a Two-Part Series of Columns

This is Part Two in a two-part series of columns.  Part One in the series appeared here on Justia’s Verdict on Wednesday, March 20. –Ed.

In Part One of this column, I considered the case of Maryland v. King, currently before the U.S. Supreme Court, which asks whether police may routinely take DNA from suspects who have been arrested on probable cause but not convicted of any crime, without running afoul of the Fourth Amendment right against unreasonable searches and seizures.  Because both parties to the case accept the legality of routinely fingerprinting arrestees, I examined some of the respondent’s arguments for distinguishing fingerprinting from DNA-sampling, and I considered these arguments in light of relevant Supreme Court precedents.  Here in Part Two, I will continue my analysis of the question presented by the case and offer an account of why DNA might be different and what consequences that difference ought to have.

How Else Is DNA Different From Fingerprints?

Beyond distinguishing fingerprinting from DNA testing on the ground that no special law-enforcement interest justifies the latter, King’s attorney also argued to the Court that taking a DNA swab is itself more intrusive than taking fingerprints.  This argument strikes me as quite weak.  The process of taking a DNA sample typically involves having one’s cheek swabbed.  The process of fingerprinting involves having one’s hands inked and then rolled on paper.  As between the two, I imagine that many readers would find the second more intrusive than the first, as Justice Breyer at one point during the argument suggested that he himself would.

Beyond the process itself, however, King’s attorney added at oral argument that fingerprinting should trigger no Fourth Amendment reasonable expectation of privacy at all, because fingerprints are visually available to everyone, whereas DNA is not.  This argument, to my mind, is simply ridiculous.  Under ordinary circumstances, we cannot see people’s fingerprints without the use of some technology or color contrast.  A police officer cannot, for example, look at a suspect’s fingers and say “Wow!  I remember seeing those same fingerprints on the murder weapon!”  That is why we have a process for “taking” fingerprints, rather than simply eyeballing them from a distance.

Conversely, a suspect’s DNA is also available to everyone, in the sense that the suspect will shed that DNA wherever he happens to be, including the detention cell where he sleeps.  Indeed, Chief Justice Roberts advanced this very point as an argument for finding that people in custody really do not have any reasonable expectation of privacy in their DNA, given how easily it can be obtained from a cup of water from which a suspect has drunk, without anyone even having to subject the suspect to a sampling procedure.

What Really Makes a DNA Test Intrusive

In my view, the only real reason to be concerned about DNA sampling (versus fingerprinting) has to do with the information that can be found in DNA, not the process of obtaining it through a cheek swab.  The government can use a person’s DNA to learn all sorts of private, non-criminal facts about the person, including his health profile and susceptibility to various illnesses.  Fingerprints do not contain this information, and people undoubtedly ought to have a reasonable expectation of privacy in it.

The problem with this argument, however, is that Maryland regulations incorporate federal standards that limit DNA analysis to the parts of DNA that serve only identification purposes, in order to protect the suspect’s privacy in the remaining DNA that would reveal more personal information.  The law thus prohibits the use of an arrestee’s DNA to learn such personal facts about him as his medical condition.  It permits the government to analyze the DNA only for the purpose of collecting identifying information, the sort of information that would allow for a match between the suspect and cold cases or “known criminals” databases.

We know from the Court’s existing precedents, moreover, that a person lacks any reasonable expectation of privacy in the fact that he was involved in criminal activity.  This is why, for example, testing a defendant’s white powder to see whether it is cocaine invades no reasonable expectation of privacy, under United States v. Jacobsen, and it is also why a dog sniff of a car for the presence of contraband invades no reasonable expectation of privacy, under Illinois v. Caballes.  If police use DNA to learn only about a person’s involvement in prior crimes, then their actions do not constitute a Fourth Amendment “search” requiring any sort of individualized suspicion.

King’s attorney had what may appear to be a persuasive response to this argument.  His response was that once police are in possession of a person’s DNA, they cannot be trusted to use it to find out only those facts that the law permits them to find out.  They can easily exceed the scope of that permission and learn personal, private, intimate facts about the suspect that they have no right to know.  King’s attorney describes the government’s response to this state of affairs as a “Just trust us” defense.

This argument, however persuasive, though, proves too much.  Any time police have the authority to perform a search that is limited in scope, they can exceed the scope of that authority.  When police search a house on the authority of a warrant, for example, we must trust them not to open drawers that the warrant does not authorize them to open.  If they are bent on violating the Fourth Amendment and exceeding the scope of the warrant, then they can easily do so once they have access to the inside of someone’s home.  As Justice Breyer noted during the argument, once the government lawfully obtains an individual’s fingerprints, they can similarly abuse their authority by matching those fingerprints against locations where the individual had every right to be, and where the individual wished his presence to remain private.  Likewise, a urine test for narcotics can also be used to examine other, legitimately personal, facts about a suspect, such as whether she is pregnant, or whether he has diabetes.  And a dog who is trained to indicate to a police officer whether a car contains narcotics can be trained to let the police officer know additional—and more private—facts about the contents of the car, since the power of a dog’s sense of smell is not limited to ascertaining the presence of cocaine or marijuana.

Granted, it may nonetheless be that the information contained in DNA is greater and more extensive than the information that police can learn from these other sorts of searches, when they go beyond the scope of what is permissible in both zones.  A decision for King on this ground would essentially assume that the government will violate the legal limits on what can be gleaned from gathered information, and that the Court must therefore place Fourth Amendment limits on the taking of DNA itself, even when DNA is taken for legitimate and constitutionally valid purposes.

If this is the ground for the decision, however, then we are in trouble, because—as Chief Justice Roberts noted—DNA can easily be gathered without having to perform a swab, simply from a cup used by the suspect to drink water (or perhaps from the detainee’s dirty laundry).  If we truly cannot trust the police to confine the scope of their searches to statutorily- and constitutionally-dictated limits, then the Supreme Court’s decision—as to whether to permit or to prohibit DNA sampling—will thus have little practical impact on the privacy of people who have been arrested.  And if Fourth Amendment limits can restrain police from extracting private information from DNA, then there appears to be no good reason to distinguish fingerprinting from DNA sampling, along any of the dimensions that respondent proposes.  Accordingly, I would conclude that a government victory represents the right result in King.