In recent years, lower courts have struggled to figure out how the Fourth Amendment applies to the collection of DNA from a suspect to try to prove identity in a criminal case (typically in rape cases). In general, courts have held that if a suspect uses a cup and throws it away, or spits on a sidewalk, the police can recover the cup or the spit and test it without triggering the Fourth Amendment. The suspect has “abandoned” the DNA, the thinking goes, so he has no continuing Fourth Amendment right in it. On the other hand, if the police for a suspect to submit to a DNA test, such as a inner-cheek swab for saliva, the suspect has Fourth Amendment rights in the DNA. Courts have not settled on exactly what protection the Fourth Amendment applies in those cases, and in particular whether a warrant or just some cause is needed to force the cheek swab. But they agree that there is at least some Fourth Amendment protection.
In Raynor v. State, the suspect in a rape case was asked to come to the police station for an interview. At the station, he was asked to submit to a DNA sample. The suspect refused. When the suspect left, however, the police swabbed the chair in which he had been sitting and were able to collect his DNA:
At that time, appellant was wearing a short-sleeved shirt and, according to Trooper Wenger, “kept rubbing his arms up and down the armrests of the chair.” . . . After appellant left the police barracks, Sergeant Decourcey swabbed the armrests of the chair on which appellant had been sitting. The swabs were submitted to the Maryland State Police Forensic Lab, where the forensic sciences supervisor, Bruce Heidebrecht, extracted DNA from the swabs and developed a DNA profile for comparison purposes. That DNA profile was found to match the DNA profile developed from the evidence taken from the pillow case and the patio at the scene of the crime.
Held, by the Court of Special Appeals of Maryland: The collection and analysis of the DNA was not a Fourth Amendment search. From the opinion:
DNA evidence, when used for identification purposes only, is akin to fingerprint evidence. And, although fingerprint evidence is suppressible if it is obtained in the course of an unlawful detention, see Hayes v. Florida, 470 U.S. 811, 816 (1985); Davis v. Mississippi, 394 U.S. 721, 727 (1969), the fingerprinting process itself “involves none of the probing into an individual’s private life and thoughts that marks an interrogation or search.” See United States v. Dionisio, 410 U.S. 1, 15 (1973) (quoting Davis, 394 U.S. at 727).
Thus, even if appellant could demonstrate a subjective expectation of privacy in his DNA profile, he nonetheless had no objectively reasonable expectation of privacy in it because it was used for identification purposes only. As in Williamson [an earlier Maryland case involving recovery of a cup the suspect had used and thrown away], the police were in lawful possession of the item from which the DNA was collected. In Williamson, the cup from which the DNA was collected came into police possession when the suspect discarded it in the holding cell; here, the chair in the police barracks was, from the outset, in the possession of the police. Thus, like the analysis of a latent fingerprint, which involves no physical intrusion into the body and is used for identification purposes only, the analysis in the instant case of DNA evidence, which was in the lawful possession of the police, was not a constitutionally protected search.
I don’t yet have a settled view of how the Fourth Amendment applies to the collection and analysis of DNA, but the analogy between DNA and fingerprint evidence strikes me as questionable. Fingerprint evidence is on the surface. It is often visible to the unaided eye, and anyone can pick it up. In contrast, obtaining a DNA sample requires extracting it from a sample, in ways that in some ways resemble drug testing of urine samples. Although the law isn’t totally clear on this, there is some authority for the view that the extraction may make a Fourth Amendment difference, see Skinner v. Railway Labor Executives Assn (1989) (holding that collection and drug-testing of a urine sample is a search, in part because of what the chemical analysis reveals). I think you can see the questionable fit here in the court’s suggestion that limiting the use of the DNA sample to identification purposes is important: It’s not clear to me how that could be right, given that the Fourth Amendment does not impose use restrictions.
Thanks to FourthAmendment.com for the link.