Two jury simulation experiments tested participants’ sensitivity to variations in the probative value of a piece of negative forensic evidence: failure to find gunshot residue (GSR) on a defendant alleged to have fired a gun. Experiment 1 found that if no GSR was detected, juries (N = 115) of undergraduates were appropriately less likely to convict a criminal defendant when the probability of detecting GSR was high than when it was low. Participants were unaffected by contextualizing expert testimony that emphasized either the value of the negative evidence for making inductive inferences or that the negative evidence was inconclusive for making deductions. Experiment 2 used a sample of venire jurors (N = 420) and manipulated the probability of detecting GSR (0 percent, 50 percent, 60 percent, 90 percent, or 100 percent) given that a gun was fired. Consistent with the first experiment, venire jurors were more likely to convict when the probability of detection was 0 percent or 50 percent than when it was 100 percent, but verdicts did not differ between the middle groups. This pattern of results suggests that jurors may evaluate negative evidence according to a fairly crude metric—giving it no weight if the probability of detection is zero, a great deal of weight if the probability of detection is 100 percent, and moderate weight if the probability of detection is somewhere in between.

Several forensic sciences, especially of the pattern-matching kind, are increasingly seen to lack the scientific foundation needed to justify continuing admission as trial evidence. Indeed, several have been abolished in the recent past. A likely next candidate for elimination is bitemark identification. A number of DNA exonerations have occurred in recent years for individuals convicted based on erroneous bitemark identifications. Intense scientific and legal scrutiny has resulted. An important National Academies review found little scientific support for the field. The Texas Forensic Science Commission recently recommended a moratorium on the admission of bitemark expert testimony. The California Supreme Court has a case before it that could start a national dismantling of forensic odontology. This article describes the (legal) basis for the rise of bitemark identification and the (scientific) basis for its impending fall. The article explains the general logic of forensic identification, the claims of bitemark identification, and reviews relevant empirical research on bitemark identification-highlighting both the lack of research and the lack of support provided by what research does exist. The rise and possible fall of bitemark identification evidence has broader implications-highlighting the weak scientific culture of forensic science and the law's difficulty in evaluating and responding to unreliable and unscientific evidence.