Though Inconclusive, DNA Evidence Could Not Be Excluded

In prosecution for possession of cocaine base with intent to distribute, admitting expert's testimony that DNA tests were inconclusive regarding the link between the defendant and DNA recovered from a cocaine bag found in the bedroom of the defendant's girlfriend; the DNA tests suggested that while the defendant could not be identified as having a connection to the bag, nor could he be eliminated as a suspect since the DNA on the bag had a chrosome marker possessed by a few other men as well, rendering the DNA evidence merely suggestive of the defendant's presence in the room, rather than his possession of the bag, in United States v. Kent, 531 F.3d 642 (8th Cir. July 7, 2008) (No. 07-2920)

We have previously discussed some of the uses of DNA evidence in federal courts. See, e.g., DNA Posts. However, the large bulk of these blog posts tend to focus on procedural issues regarding the use of DNA tests, rather than their use or abuse as substantive evidence at trial. Several years ago, the Eighth Circuit considered why a DNA test that was inclusive might still be relevant at trial of a drug offense. The case offers an interesting twist on the role of relevance and DNA evidence.

In the case, an city police officer trying to serve an arrest warrant on the defendant. Based on a tip that the defendant was driving a black car, officers stopped a car he was driving arrested him. However, the car was registered to a woman and not to the defendant. Accordingly, officers went to the woman’s house to find out why the defendant was driving the car. The car's owner, she said had loaned the vehicle to the defendant with whom she was currently living. However, she also consented to the search of her room. In that room, officers came across a revolver, cash, and crack cocaine. At the police station, the defendant permitted a DNA swab to be taken. DNA testing confirmed that his DNA was located on bed sheets and on cigarette butts found in his girlfriend's room. Photographs on his cell phone showed the defendant having sex with her. Based on these connections, the prosecution added drug distribution charges to charges that had brought the defendant to police attention initially. At trial, a DNA expert testified that the defendant could not be excluded as the person who contributed DNA found on one of the crack cocaine bags seized from Amy’s room. As explained by the Circuit

The DNA expert testified at trial that one of the crack cocaine bags found in Amy Doyle's room had a mixture of at least two people's DNA on it, one male and one female. The male DNA was consistent with Kent's (all 12 of Kent's Y chromosome alleles from his swab were present on the Y chromosome alleles on the crack bag). The expert could not testify that Kent was definitely the contributor of the DNA, however, because all males in Kent's family have the same marker on their Y chromosomes. The expert's opinion, therefore, was only that Kent could not be excluded as a contributor of the DNA."
Kent, 531 F.3d at 651.

The circuit noted that the basis of the defendant's objection was not founded on the reliability or unrealibility of the DNA evidence under FRE 702. Rather, the defendant presented a relevance argument, which took the circuit a sentence or two to dismiss:

Expert testimony is admissible if it will “assist the trier of fact.” Fed. R. Evid. 702. Evidence is relevant if it will have any tendency to make the existence of any fact of consequence more or less probable than it would be without the evidence. Fed. R. Evid. 401. “The district court enjoys broad discretion in its determination of relevancy.” “[A DNA test] ‘cannot exclude’ finding can tell a lot, and can increase the probability that the person's DNA is present.
Kent, 531 F.3d at 651 (citing United States v. Robertson, 387 F.3d 702, 704 (8th Cir. 2004); United States v. Mitchell, 502 F.3d 931, 970 (9th Cir. 2007) (“[A] ‘cannot exclude’ finding can tell a lot, and can increase the probability that the person's DNA is present.”), cert. denied, 553 U.S. 1094 (2008).

Federal Rules of Evidence