The Devil Is in the Debris: How Contextual Deficiency in Forensic Fire Debris Analysis Contributes to Wrongful Convictions

Forensic science plays a pivotal and occasionally paradoxical role in the American criminal legal system. It helps solve crimes, yet also contributes to the conviction of innocent people. Although much of the scholarly literature related to the link between forensic science and wrongful convictions has focused on dubious forensic disciplines (so-called instances of “junk science”), this Essay examines valid forensic evidence that is misused or misunderstood within the greater context of the case. Specifically, we focus on overturned arson cases involving forensic fire debris analysis, exploring how scientifically accurate conclusions—such as the presence of ignitable liquid residues in evidence—can still lead to wrongful convictions when misattributed. In the process, we introduce the concept of “contextual deficiency.” Contextual deficiency occurs when the criminal legal process fails to properly integrate the results of scientifically valid forensic tests with case-specific contextual information. This can take place when there are innocuous reasons for the presence of the evidence (e.g., inherent chemicals in floorboards) or an intervening process undermines the probative value of the evidence (e.g., secondary transfer of DNA). Contextual deficiency can arise at almost any stage of the investigation and adjudication, from the forensic scientists to the prosecutors and jury. While all forensic evidence can be taken out of context, there are certain areas of testing that are more susceptible to contextual deficiency. Forensic fire debris analysis, often used in arson investigations, is one such discipline. [From the Introduction]