Some notes on Perceived infallibility of detection dog evidence: implications for juror decision-making

a good boy.

a good boy.

I just read Lisa Lit and colleagues’ “Perceived infallibility of detection dog evidence: implications for juror decision-making ” (Criminal Justice Studies). Since reading about the role of dog evidence in the wrongful conviction of Guy Paul Morin, I’ve wondered about how such evidence is used at trial - this paper filled in some of those gaps for me, and provided some new empirical evidence.

The article provided a brief background into how courts evaluate dog drug detection evidence (in the U.S.). It sounds an awful lot like how they evaluate other contentious forensic expert evidence:

Detection dog evidence is among the more technical areas of forensic science, and scientific falsifiability would be a high threshold for it to meet given the common challenges associated with this form of evidence. In practice, however, the 2013 Harris v. Florida Supreme Court case ‘closed the door on science-based challenges to the reliability of canine sniff evidence’ (Shoebotham, 2016, p. 227). Rather than confronting the fundamental usage of detection dog evidence, the Harris case accepted this practice and instead limited questions of reliability to the performance of individual dogs (Shoebotham, 2016; Taslitz, 2013).

In assessing a particular dog’s reliability, the courts weigh its training and certifications, and in some cases, field performance (Fazekas, 2012; Shoebotham, 2016; Taslitz, 2013). Anecdotal support for dog training and certification is routinely provided by handlers and dog industry professionals who are considered expert witnesses, including the training and certification protocols recommended by The Scientific Working Group on Dog and Orthogonal Detector Guidelines (SWGDOG). However, it is important to note that there are no national standards for dog training and that certifications are typically generated and provided by the private agencies that train and then ultimately sell detection dogs (Johnen, Wolfgang, & Fischer-Tenhagen, 2017; Minhinnick, 2016; Shoebotham, 2016). Accordingly, when it comes to the reliability and admissibility of detection dog evidence, the Harris case has resulted in the Daubert Standard’s threshold of scientific falsifiability being superseded by criteria that are more subjective and prone to bias.

The article goes on to mention research supporting the impetus behind the authors’ study: drug detection dogs do have an error rate (apparently about 10%, but it doesn’t say exactly how that was measured and if it’s the false positive rate). But, that some research has suggested that people ascribe a mystical infallibility to dog detection.

In the authors’ study, they provided jury-eligible individuals with a summary of a case in which a drug dog had detected a drug, but that the drug wasn’t actually found. 33.5% of participants indicated they found find the person guilty and 66.5% did not. The main finding was that there was a correlation between guilty verdicts and belief in dog drug detection.

As a whole, I found the review in this article quite useful and it’s interesting that people indicate they will find people guilty for drug offenses despite the drug not being found, and that they place such great weight on dogs. There were some exploratory analyses in here (some properly flagged as exploratory, like relationships between study variables and need for cognition). I’d encourage the authors to preregister these analyses in the future.