Monthly Archives: March 2013

The Constitutionality of DNA Collection Before Conviction: An Updated Scorecard

Fifteen years ago, Louisiana adopted a law mandating that “[a] person who is arrested for a felony sex offense or other specified offense . . . shall have a DNA sample drawn or taken at the same time he is fingerprinted pursuant to the booking procedure.” As of mid-2012, 28 states and the federal government had laws providing for DNA sampling before any conviction is obtained. Most other countries with DNA databases also collect samples on arrest.

These laws have provoked conflicting constitutional opinions. The Supreme Court heard argument in Maryland v. King in February 2013 and is likely to rule on the issue in June 2013. For a scoreboard on the litigation and a list of scholarly commentary to date, see

Are Two Heads Better than One? Mathematics and the Amanda Knox Case

In yesterday’s New York Times, “Leila Schneps, a mathematician and mystery writer, and her daughter Coralie Colmez” wrote an op-ed entitled “Justice Flunks Math.” They gave this failing grade to an Italian judge who declined to order a second DNA test in the notorious murder case against the American student, Amanda Knox and her Italian ex-boyfriend, Raffaele Sollecito.

If only the judge understood probability theory, they suggest, he might have ruled in favor of the prosecution’s request for another DNA test. As explained in Forensic, Science, Statistics, and the Law, I am not sure that their criticism of “bad judicial math” in this case computes.

Disgusting DNA: Striking Transit Workers

In England, the national DNA database has been employed to curb spitting on transit workers. As part of Operation Gobstopper, bus drivers in northwest London received 2,500 evidence collection kits. Tube staff in central London and train wardens in Scotland were similarly equipped, the BBC reported in 2004.

The kits helped prosecute about 100 people on the Tube in 2007. Reportedly, 7 out of 10 samples yielded a match to DNA profiles in the national database of criminal offenders and arrestees.

Cross-posted to Forensic Science, Statistics, and the Law

Disgusting DNA: The Whopper and the Copper

When my son worked at a pizza restaurant a long time ago, he told me that some of the kids preparing the food would spit into into their handiwork. I tried not to think about it, but the practice, at a Burger King in Vancouver, Washington, prompted a major decision on the tort of intentional infliction of emotional distress — and an unusual DNA-centered investigation. >> read more

Hot Off the Presses: Recent Publications

The final version of On the ‘Considered Analysis’ of Collecting DNA Before Conviction, previously mentioned, is now published in UCLA Law Review Discourse, Vol. 60, 2013, pp. 104-126. It is available on the review’s website or from SSRN.

A short essay on the relative insignificance of chimerism as a source of error in forensic DNA testing is in print: Chimeric Criminals, Minnesota Journal of Law, Science, and Technology, Vol. 14, No. 1, Winter 2013, pp. 1-9. It is available on the review’s website or from SSRN. Jeremy Gans has a thoughtful comment posted on Forensic Science, Statistics, and the Law.

The Oral Argument in Maryland v. King — Part V

It is time to sum up and read the tea leaves that are the transcript of the February 26th oral argument in Maryland v. King. Previous postings concerned these topics:

Part I

  • Whether taking DNA profiles of arrestees is distinguishable from acquiring them from the general population;

Part II

  • Whether deriving information from database trawls that could inform pretrial release decisions and conditions can constitute a special need for warrantless DNA acquisition now or in the future;

Part III

  • Whether DNA profiles are distinguishable from fingerprints on the theory that collecting fingerprints is not even a search;
  • Whether DNA samples are distinguishable from fingerprints because DNA samples contain more personal information;

Part IV

  • Whether Kyllo‘s analysis of thermal imaging of a home applies to DNA profiling;
  • Whether the Court’s precedents show it is unwilling to trust the government;
  • How Skinner, Greenwood, and Davis (4th Cir. 2012) affect the claim that a laboratory analysis limited to identifying features is a search in its own right.

At least some of the Justices appeared to be searching for a theory that would distinguish routine DNA collection and analysis before conviction (DNA-BC) for arrestees from the DNA-BC for everyone in the population. But why? � read more �

The Oral Argument in Maryland v. King — Part IV

The previous installment of this series described counsel’s answers to questions as to how DNA profiling is different from fingerprinting. After pointing out that “there are profound privacy concerns associated with the government’s collection of an individual’s DNA” because “when you evaluate the entirety of an individual’s DNA, there is a great deal of personal information contained there,” counsel for Mr. King added that

Now, the government’s response to that is essentially the “just trust us” defense; namely that the government is not looking at all that information, it is only looking at a certain subset of that information. But that has never been how this Court has analyzed privacy interests, at least outside the special needs context. Probably the closest analog is this Court’s decision in Kyllo v. United States, where the Court said that it was of no moment that the heat-sensing device that was at issue in that case did not detect any information about the intimate details of activities within the home.

I think this is inaccurate (or at least incomplete, as oral argument often is). … [Read the full posting]

The Oral Argument in Maryland v. King — Part III

At the oral argument in Maryland v. King, the Justices wanted to know why DNA collection and databases were more personally intrusive or destructive to other privacy interests than fingerprint collection and databases. In response, Mr. King’s counsel advanced two formal, doctrinal points: He questioned whether fingerprinting even amounted to a search (because fingers are external and visible); and, referring to the limits on the “special needs” doctrine (see yesterday’s posting), he emphasized that fingerprint systems create a permanent record of individual identity for authentication of identity, whereas, at the moment, DNA is primarily used for criminal intelligence purposes (that is, for solving crimes). He also mentioned the most fundamental point — that DNA samples reveal more about an individual than his fingerprints — but the Justices did not pursue it directly.

Let us look at the exchanges on the nature of fingerprinting. Justice Alito focused on the methods for collecting fingerprint and DNA samples when he asked:

JUSTICE ALITO: Well, do you think the intrusion is worse when you just take a swab and you go inside somebody’s cheek, as opposed to rolling fingerprints?* Which is the greater intrusion?

Apparently, Mr. King’s position was that because the swab goes into the mouth, DNA sampling is the more invasive procedure:

MR. SHANMUGAM: Well, we think that it is settled that intrusions into the body constitute a search for Fourth Amendment purposes.

JUSTICE ALITO: Which is [the greater intrusion?]–

MR. SHANMUGAM: I suppose that the argument could be made, Justice Alito, that there is a similar trespass on the person and, therefore, a search when fingerprints are collected. I would note parenthetically that in the first half an hour of this argument we heard no explanation either by the state or by the federal government as to their theory as to why fingerprinting is constitutional. Now, we —

Justice Alito persisted in his demand for a more satisfying explanation of the difference:

JUSTICE ALITO: Well, the thrust of a lot of what we have been presented with in the briefs and what we have heard this morning — and by the way, I think this is perhaps the most important criminal procedure case that this Court has heard in decades — the attorney for the State began by listing a number of crimes just in Maryland that had been solved using this. So this is what is at stake: Lots of murders, lots of rapes that can be — that can be solved using this new technology that involves a very minimal intrusion on personal privacy. But why isn’t this the fingerprinting of the 21st century? What is the difference? If it was permissible — and it’s been assumed to be so for decades — that it is permissible to fingerprint anybody who’s booked, why is it not permissible to take a DNA sample from anybody who is arrested?

MR. SHANMUGAM: Justice Alito, we think that fingerprinting is distinguishable on three grounds. First of all, as a practical matter, an individual’s DNA contains far more information and far more personal information than an individual’s fingerprints. But as a doctrinal matter, we think that fingerprinting is distinguishable —

JUSTICE ALITO: Well, as to the first, in our cases involving searches for — where a urine sample is taken to determine drug use, the urine can be analyzed for all sorts of things besides the presence of drugs, and the Court has said in those cases, we are only going to consider that — we are considering that this is a reasonable search with respect to the determination of whether the person has taken drugs, not all the other information … that can be obtained from it.

MR. SHANMUGAM: But that is because, Justice Alito, in those cases, cases like Skinner and Von Raab and Vernonia, there was a special need apart from the ordinary interests in law enforcement. And here it is clear that the primary purpose of the Maryland statute and, indeed, the similar statutes on the federal and state levels was the ordinary interest in crime control, to solve unsolved crimes. And that is why those special needs cases are distinguishable, and I think that’s why the state essentially disavows any reliance on the special needs doctrine.

So far, the question of how collecting DNA compares in its intrusiveness to recording fingerprints has gone largely unanswered. Justice Breyer certainly was not satisfied that the degree of intrusion was greater for a cheek swab:

JUSTICE BREYER: [I]f I look in terms of intrusion —  [and] I am not talking legally, I am talking practically — … I can argue that it is certainly a much lesser intrusion than fingerprints. You [only] have to stand there, have the thing rolled, stick out your tongue. I mean, it’s hard to say it’s more [intrusive — at least] for me. I’m not saying for others. …

Justice Breyer’s suggestion that having a swab inserted into one’s mouth is less invasive than having one’s fingers inked and rolled onto a card hardly seems convincing. My intuition is that the swabbing adds to the demeaning and humiliating nature of a modern, custodial arrest more than fingerprinting. Nevertheless, any difference in the level of offensiveness is slight, and the very question seems to miss the real point. If the limited invasion of the body were the decisive factor, then the government could sidestep the concern entirely by scraping some cells from the surface of the skin. A sticky pad might supply enough DNA for profiling, making the procedure indistinguishable from fingerprinting in terms of the physical intrusion.

At this point, then, we are left with one distinction between fingerprinting and DNA sampling — that “[f]irst of all, as a practical matter, an individual’s DNA contains far more information and far more personal information than an individual’s fingerprints.” Obviously, this concern about informational privacy has nothing to do with the process by which the information is obtained. It would apply even if DNA could be analyzed at a distance, with no physical contact between the police and the suspect.

But the Court did not immediately pursue this proffered distinction. Instead, Justice Kagan asked:

JUSTICE KAGAN: What are your other two distinctions?

MR. SHANMUGAM: With regard to fingerprinting, we think that, notwithstanding the physical intrusion involved with taking an individual’s fingers and putting them on the pad, that the better view is that fingerprinting is not a search, and to the extent that this Court has addressed the question it has suggested that fingerprinting is not a search because an individual has no expectation of privacy in their fingerprints because their fingers are constantly exposed —

Now, there are some lower court cases that take this point of view, but it seems to undercut Mr. King’s position. If fingerprints are not a search because the fingers that produce them are constantly exposed to public view, then DNA profiles are not a search because cells that contain DNA also are constantly exposed. To be sure, the Supreme Court has suggested (and held) that the Fourth Amendment does not shield features such as one’s voice and face that are constantly exposed to public view, but the Court has never considered whether recording or comparing fingerprints constitutes a search. The few Supreme Court cases finding fingerprints to have been unconstitutionally obtained have simply treated the detention of the individual–a seizure of the person–as the event that triggered the protection of the Fourth Amendment, and the personal interest in freedom of movement is the same for DNA collection as for fingerprinting.

It was at this point that Justice Breyer made the remarks quoted above, and he went on to express skepticism of the informational privacy claim as well:

JUSTICE BREYER: And by the way, when you talk about what information you could get out of it, there is a brief filed by leading scientists in the field. And I came away from the brief thinking there isn’t much more information, because fingerprints can be abused, too. Of course, you can learn loads from fingerprints. Photos, try photos; my God, you could learn a lot: Who he was, who — you know, so all these things could be abused. But I came away from that brief, frankly, to think, well, in terms of the possibility of abuse, it’s there, but [it’s also present with] these other things, photos, too. … Now, you tell me in light of that hostile question (laughter) [how] it’s different from fingerprints and worse because of one, two, three, and I will write it down and I’ll remember it.

JUSTICE SCALIA: He gave us one and two. I have been waiting for three. Will you drop the shoe? (Laughter.)

MR. SHANMUGAM: Let me — I will gladly get to three with regard to fingerprinting … . [W]e think fingerprinting is different, above and beyond the fact that we think … that fingerprinting is not a search, … because fingerprinting as it is currently practiced does serve a special need. The primary purpose of fingerprinting is to identify an individual who is being taken into the criminal justice system.

If Justice Breyer did write down Mr. King’s proposed distinctions, he might have the following list: (1) DNA samples contain more information than fingerprint records; (2) collecting and using fingerprint records should not be considered a search because fingers are visible; and (3) fingerprints are taken on arrest primarily to ascertain whether an individual is who he claims to be and to see if he has a criminal record (and only secondarily to connect arrestees to crimes through comparison to latent prints). The latter two proposed distinctions are important only with respect to nuances of contestable caselaw. They do not directly address the fundamental question of the relative invasion of personal interests. In this regard, the only direct answer on the list is that “an individual’s DNA contains far more information and far more personal information than an individual’s fingerprints.”

Still, this is an important answer. I had expected the informational privacy issue to provoke more discussion. Although counsel for Mr. King stressed the issue in a reply to Justice Sotomayor,** only Justice Breyer picked up on it, and in doing so, he became the first jurist (to my knowledge) to recognize that fingerprint patterns are not entirely devoid of personal information.

Fingerprints have a genetic component, and the scientists’ brief to which Justice Breyer referred has a three-and-one-half page appendix listing “some studies reporting diseases associated with fingerprint features.” This brief (discussed in “Scientists’ Brief” on CODIS Loci: Q & A) focused on the information content of CODIS profiles, not samples. It suggested that even these profiles contained somewhat more personal information (being fully inherited characteristics) than fingerprint patterns (being influenced by both genes and the uterine environment).

The brief does not dispute — indeed, it presupposes — that DNA samples are replete with information. Yet, the issue of sample retention did not arise in the argument, and a few of the Justices even suggested that the ease with which police and private parties can acquire samples in other ways might defeat a reasonable expectation of privacy. The next posting will turn to this issue of “shed” or “abandoned” DNA.


* “Rolling” refers to the process by which each inked digit is rotated slightly from side to side while pressed on a cardboard surface to yield a permanent, ten-print card. Digital scanning is growing more common, but Justice Alito may have picked the messier inking process as the procedure to be compared because, for many years, lower court had upheld as constitutional fingerprinting arrestees in that manner, and Justice Alito regarded these holdings as correct.

** JUSTICE SOTOMAYOR: I was interested in [whether] there is something inherently dangerous about DNA collection that is not the same as fingerprinting.

MR. SHANMUGAM: Well, there is, … . [W]e certainly believe that there are profound privacy concerns associated with the government’s collection of an individual’s DNA. And leaving aside the question of how much personal information is contained in the 13 loci — and we certainly think that there is significant personal information even as to those loci — I don’t think there can be any dispute that when you evaluate the entirety of an individual’s DNA, there is a great deal of personal information contained there. And in our view, that has to be taken into account when engaging in balancing.

Cross-posted to Forensic Science, Statistics, and the Law.

The Oral Argument in Maryland v. King — Part II

As noted yesterday, the argument that DNA profiling and database trawling for past crimes is or will be useful for pretrial release determinations intrigued several of the Justices. Justice Sotomayor spoke up:

JUSTICE SOTOMAYOR: And I’m having a hard time understanding the bail argument.Because in my time, most bail decisions were made at the time of arrest. And here the arrest was in April and the results didn’t come up until August. … You don’t use it routinely for the bail determination.

MS. WINFREE: At this point, you’re absolutely correct, Justice Sotomayor. We don’t use it routinely for a couple of reasons. For one, as in Mr. King’s case, there has been in the past a more substantial delay in getting those results back. Our — our lab now is getting results between 11 and 17 days. … Now, of course, that wouldn’t be timely for that first bail determination, but the State under Maryland’s procedure certainly has the ability to go back to — to the judge and ask that … that bail determination to be modified. And in point of fact, … in California’s amicus brief, which was joined by the 49 other States and D.C. and Puerto Rico, they actually do cite two particular examples where [release or] diversion was revoked . …

The Deputy Solicitor General maintained that this use of the DNA would only grow:

MR. DREEBEN: [R]apid DNA will permit DNA identification to replace fingerprint identification because it’s far more accurate and it has far more utility in the secondary purpose of fingerprints, which is to match them to latent prints and solve crimes. … Any judge who is looking at a bail case would like to know: I have a guy who has been arrested on grand theft auto. He has no criminal history. Should I release him back on the street? Well, it’s a first offense, he has family ties; maybe yes. If that … defendant’s DNA came back and returned a cold case hit to a murder-rape, the judge would know he’s not such a good risk to be put back on the street.* [* Order of clause rearranged.]

In responding to this argument, counsel for Mr. King first seemed to concede that when DNA profiling and database trawling could be done rapidly, the system would become constitutional:

CHIEF JUSTICE ROBERTS: There are two different, two different interests. One is we want to solve unsolved crimes; and the other is we want to be sure — we have someone in our custody and we want to be sure, before he is released back into the community, that he isn’t a person who has committed five violent crimes before that. Now, your brief says, well, the only interest here is the law enforcement interest. And I found that persuasive because of the concern that it’s going to take months to get the DNA back anyway, so they are going to have to release him or not before they know it. But if we are in a position where it now takes 90 minutes or will soon take 90 minutes to get the information back, I think that’s entirely different, because there you can find out whether — it’s just tied in with the bail situation, do you want to release him or not.

MR. SHANMUGAM: The touchstone of the analysis under the special needs doctrine is what was the primary purpose of the program at issue. And there is no evidence that pretrial supervision was a purpose of any of these.

CHIEF JUSTICE ROBERTS: That’s because, that’s because we are not yet at a situation where it takes 90 minutes. Sure, it’s not going to do you any good if it’s taking four months or whatever it took in this case. But if it’s at the point where it’s 90 minutes, it would be critical to make that determination.

MR. SHANMUGAM: Well, Mr. Chief Justice, … the constitutional analysis may very well change at a later point. But I think it’s important to underscore that neither the State of Maryland nor the federal government identifies a single instance in which a pretrial supervision decision in their jurisdictions was altered as a result of the DNA test.

But a little later he qualified his position:

JUSTICE SOTOMAYOR: Counsel, so I am really worried about the question … that I think one of my colleagues asked. I agree completely that today it’s used primarily and almost exclusively for purposes of solving other crimes.* But let’s — is this — the question only because technology hasn’t moved fast enough? You said we have to look at the constitutional principles 5 years from now when they will use it to pull up a guy’s criminal history. Not unsolved crimes, but criminal history. Get to that day. … Tell me what the — why you would then say that would still be unconstitutional. [* Order and wording of sentences altered slightly.]

MR. SHANMUGAM: Justice Sotomayor, … the only other potentially applicable exception to the principle that warrantless, suspicionless searches are unconstitutional is the special needs exception, and that exception looks to the primary purpose of the program at issue. And the mere fact that DNA testing could be used for other purposes wouldn’t necessarily be dispositive of the inquiry. If the primary purpose of DNA testing is still to investigate unsolved crimes, the program would still not qualify under the special needs doctrine.

Then again, under questioning from Justice Kagan, he conceded that the multipurpose system could be constitutional:

JUSTICE KAGAN: Just suppose — I mean, I guess the question is, would this be unconstitutional? It’s not the world we are living in now, but let me — 10 years from now the government says, we are really switching over to a fingerprint system — to a DNA system and what that system is going to allow us to do, is it’s going to allow us to identify, and it’s going to allow us to bring up the old criminal history and it’s going to allow us to see whether there are also unsolved crimes that we can tag to this person and discover that he’s really, really dangerous. All right? And so the government puts that system into effect. Is it constitutional?

MR. SHANMUGAM: I think that it could be, and that would simply be because you would have a system where DNA testing is essentially being used as fingerprinting is being used today. But again I don’t think —

The difficulty the Justices experienced in receiving a definitive response to their vision of a multipurpose DNA database system exposes part of the soft underbelly of the so-called special needs doctrine. One might well ask why “the primary purpose” of a program that produces evidence for criminal investigations and prosecutions is so critical? And, if it is so crucial, may a state salvage a law struck down as unconstitutional (because it was intended and used only to generate evidence in unrelated matters against mere arrestees) by re-enacting it, continuing to use it for its previous primary purpose of generating evidence, adding a new statutory preamble, and also using it (like fingerprints) for one or more additional purposes (such as gathering appropriate information for a bail determination) proclaimed in a carefully crafted preamble?

I asked these questions 13 years ago (Kaye 2001). The so-called special needs exception to the ordinary requirements of probable cause and a warrant applies when the government can articulate special interests in a program that also generates evidence of wrongdoing. For example, the government’s special interest in jail security and inmate health and safety justifies most of the searches that the Deputy Solicitor General reminded the Court about in the opening of his argument. When the government’s sole interest is producing evidence with which to catch criminals and the search is a significant intrusion of persons, houses, papers, or effects, then the normal rule is that warrants and probable cause are required. This reflects a prior balancing of governmental and personal interests that allows some searches but constrains arbitrary or unjustified government action. When special interests are present, however, the prior balancing is incomplete, and the outcome of a more comprehensive balancing could be different, As a result, the normal rule demanding warrants and probable cause might not apply (Kaye 2013).

Under this “special interests” theory, balancing is appropriate whenever special interests are present, and whether the balance of interests favors the government or individual does not depend on whether evidence production is a primary, secondary, or tertiary purpose of the program of searches. Yet, since 2000, the “special needs” doctrine has been more complicated–and less coherent than the reconstruction sketched above. As King argued, special interests do not trigger balancing unless they are the “primary purpose” of the program.

At least, this is what the Court first announced in City of Indianapolis v. Edmond, 531 U.S. 32 (2000). However. Edmond was not a multiple-purpose case. For the single purpose of finding narcotics in vehicles, Indianapolis established a program in which police used dogs to sniff for drugs in vehicles pulled over in groups at fixed roadblocks. The Court previously had upheld brief, suspicionless seizures at highway checkpoints for the such singular purposes as combating drunk driving and intercepting illegal immigrants. In addition, it had ruled that walking a drug-sniffing dog around a properly seized vehicle was not even a search. Thus, both components of the program–the checkpoints and the dog sniffs–had withstood constitutional attack. Yet, the Edmond majority reasoned that these cases did not govern: “Because the primary purpose of the Indianapolis narcotics checkpoint program is to uncover evidence of ordinary criminal wrongdoing,” the special needs exception was unavailable.

But neither Edmond nor any other case has tried to apply the primary-purpose limitation to a program that plausibly serves two or more purposes. Would the Indianapolis program have been eligible for special-needs balancing had the city established roadblocks strictly to check for intoxicated drivers, and then, after waiting a decent interval, added a dog-sniff in parallel with the sobriety check?

To cope with the analogous situation envisioned in the questions from the Chief Justice and Justices Kagan and Sotomayor, the Court has at least two stark choices. It could overrule Edmond and abandon the primary-purpose restriction, allowing special needs balancing as long as special interests actually are present. Or, it could engage in a slightly mystical search for the “primary” purpose of a truly multipurpose program.

But even if the special needs exception would apply in the future, the Chief Justice asked, what does it mean for the Maryland law today?

CHIEF JUSTICE ROBERTS: How can I base a decision today on what you tell me is going to happen in two years? You say, in two years we will have this rapid DNA available, but we don’t now. Don’t I have to base a decision on what we have today?

MS. WINFREE: Well, that’s really only one component of our argument, Mr. Chief Justice, that certainly with respect to a bail determination we will be able to make it more rapidly at the time that rapid DNA comes into effect.

Whereupon Justice Scalia got in the last word during Maryland’s rebuttal argument. Expressing his reticence to uphold the Maryland program because of what it might become, he stated:

JUSTICE SCALIA: Yes, but if we believe that the purpose of it has much to do with whether it’s legitimate or not, you can’t demonstrate that the purpose is immediate identification of the people coming into custody. You just can’t demonstrate that now. Maybe you can in two years. The purpose now is — is the purpose you began your presentation with, to catch the bad guys, which is a good thing. But you know, the Fourth Amendment sometimes stands in the way.


1. David H. Kaye, The Constitutionality of DNA Sampling on Arrest, 10 Cornell J. L. & Pub. Pol’y 455 (2001), available at

2. David H. Kaye, A Fourth Amendment Theory for Arrestee DNA and Other Biometric Databases, 15 U. Pa. J. Const. L. No. 4 (forthcoming 2013), available at

Cross-posted to Forensic Science, Statistics, and the Law

The Oral Argument in Maryland v. King — Part I

Oral argument before the Supreme Court in Maryland v. King took place on Tuesday, Feb. 26.1/ Alonzo King, Jr., had been arrested in 2009, then charged and convicted of an assault. A Maryland law requires defendants charged with certain crimes to provide a DNA sample–before they are even tried. On this basis, King’s identifying DNA profile was obtained and included in a database of DNA profiles from arrestees and convicts, to be checked periodically against DNA profiles recovered from crime scenes.

King’s DNA profile played no role in the assault case. The state did not want it for that prosecution. Rather, it wanted to see if his DNA might connect him to some unsolved crime. Sure enough, it linked him to an unsolved 2003 rape of a 52-year-old woman. In the ensuing trial for that crime, the state proved that King, then 19 and wearing a mask, broke down the door, held a gun to the woman’s head and sexually assaulted her. He was sentenced to life in prison.

The question before the Supreme Court was whether the state’s law mandating routine DNA sampling before conviction violates the Fourth Amendment’s protection against unreasonable searches or seizures.

I had the worst seat in the house — a small wooden chair against the far wall behind the farthest row of permanent seats. That hardly mattered. From any distance,  the argument would have appeared kaleidoscopic, with patterns forming and shifting apparently at random. Nevertheless, one major theme emerged from the questions: Is the rationale for upholding Maryland’s law confined to arrestees? Several Justices clearly were concerned that upholding this law would permit states or the federal government to acquire the DNA of everyone.

The Chief Justice introduced this line of questioning earlier in the argument for the state:

CHIEF JUSTICE ROBERTS: Your procedure limits the collection to certain violent offenses, right?

MS. WINFREE: It does, Mr. Chief Justice.

CHIEF JUSTICE ROBERTS: But your argument would not be so limited, would it? Under your theory, there’s no reason you couldn’t undertake this procedure with respect to anybody pulled over for a traffic violation?

MS. WINFREE: Well, in Maryland, it’s not just the fact that we have those — those violent crimes and burglaries. Actually, we don’t collect DNA unless someone is physically taken into custody. Now, with respect to —

CHIEF JUSTICE ROBERTS: Well, I understand. But there’s no reason you couldn’t, right? I gather it’s not that hard. Police officers who give Breathalyzer tests, they can also take a Q-tip or whatever and get a DNA sample, right?

MS. WINFREE: Well, what I would say to that is that with respect to a traffic stop, this Court said in Berkheimer that a motorist has an expectation that a traffic stop is going to be relatively brief and temporary, that he or she will be given a citation and sent on their way.

CHIEF JUSTICE ROBERTS: Well, how long does it take to — to undergo the procedure? You say, ah and then —

MS. WINFREE: It doesn’t take long, but what I was suggesting is that because of the nature of a traffic stop, this Court might well decide that a motorist has a reasonable expectation of privacy not to —

These answers are unsatisfying. In Illinois v. Caballes, 543 U.S. 405 (2005), the Court deemed the nature of a traffic stop irrelevant to the reasonableness of a search for something unrelated to the stop. Specifically, the Court rejected the argument that walking a drug sniffing dog around a car while an officer wrote the citation “converted the citizen-police encounter from a lawful traffic stop into a drug investigation, and because the shift in purpose was not supported by any reasonable suspicion that respondent possessed narcotics, it was unlawful.” Given that “governmental conduct that only reveals the possession of contraband ‘compromises no legitimate privacy interest,'” the Court concluded that the dog-sniff was not itself a search, and the traffic offense fully justified the temporary restraint on the driver’s freedom to travel was fully justified.

Rather than “the nature of the traffic stop” creating a reasonable expectation of privacy that would make the traffic-stop DNA sampling a search, it is the nature of DNA sampling (as currently conducted) that has this effect. Justice Scalia emphasized this when he later commented:

If there’s no reasonable expectation of privacy, there’s no search. But here, there is a search. You have a physical intrusion. You — you pull a guy’s cheek apart and stick a — a swab into his mouth. That’s a search — a reasonable expectation of privacy or not. 2/

Soon afterward, Maryland’s Chief Deputy Attorney General took another stab at explaining why its justifications for the law would not subject everyone to compulsory DNA sampling:

MS. WINFREE: Well, happily we don’t have to decide that one today. But what I — the cornerstone of our argument is that when an individual is taken into custody, an individual is arrested on a probable cause, on a probable cause arrest, that person by virtue of being in that class of individuals whose conduct has led the police to arrest him on — based on probable cause surrenders a substantial amount of liberty and privacy.

The U.S. Department of Justice’s Deputy Solicitor General elaborated at the outset of his presentation:

MR. DREEBEN: Thank you, Mr. Chief Justice, and may it please the Court: Arrestees are in a unique category, they are on the gateway into the criminal justice system.    They are no longer like free citizens who are wandering around on the streets retaining full impact Fourth Amendment rights. The arrest itself substantially reduces the individual’s expectation of privacy. The arrestee can be searched and sent to arrest. His property, whether or not connected with a crime, can be inventoried. When he’s taken into the jail situation, he can be subjected to a visual strip search. If he’s admitted to the population of the jail, he’ll be given a TB test and a thorough medical screen. These are not individuals who are like free citizens, and they are not like free citizens in another significant respect. Arrestees are rarely arrested for the first time. They tend to be repeat customers in the criminal justice system. Up to 70 percent of arrestees have been previously arrested.

The trouble with this argument should be obvious. Of course, arrestees have been arrested and may be searched in ways inapplicable (thankfully) to people who not currently in police custody. But the fact that “they are not like free citizens” does not necessarily mean that the justifications for taking their DNA are not just as powerful when applied to the general population. One must go beyond diffuse talk of surrendering “a substantial amount of liberty and privacy” to adequately distinguish this group from the general population for the purpose of DNA identification testing. The argument that arrestees are different just because they have been arrested (and are likely to be re-arrested) is empty.

One thing that gives the difference claim some content is the state’s argument that DNA databases do or can provide significant information for pretrial supervision of arrestees. Much of the hour’s argument focused on Maryland’s contention that the “purpose of the statute is to enable the state to identify perpetrators of serious crimes and — and to use the information to make bail determinations for people who are validly in their custody.” Part II of this series will describe the Justices’ often skeptical questioning on this point.


  1. For the same-day transcript, see
  2. On its face, this comment seems to be internally inconsistent. The first sentence asserts that there can be no search without a reasonable expectation of privacy. The third says that is a search even if there is a reasonable expectation of privacy. I take it that Justice Scalia means that one need not fuss with reasonable-expectation test when there is a traditional trespass to gather information. This was the position that the Justice articulated for a majority of the Court in United States v. Jones, 132 S.Ct. 945 (2012).

Cross-posted to Forensic Science, Statistics, and the Law.