San Diego Criminal Lawyers Blog
When there are questions about the veracity of conclusions in a court case, it is reassuring to have forensic evidence to support inferences and assumptions, isn’t it? After all, there is no arguing with science! Actually, it may surprise you to know that researchers have found plenty to question about scientific conclusions in general and forensic evidence in particular.
The Question of Context
One huge issue as it relates to forensic evidence is the context of that evidence. We all know that context can influence the interpretation of any given fact. For instance, if a red-headed woman was seen breaking a window, and you see a red-headed woman coming around the corner from the building where that window was broken, the context of the situation could lead you to conclude that the woman you now see was responsible for the break. The same is true for forensic scientists. If, for example, a crime scene investigator collects evidence and then examines it in the lab, it is logical that impressions of that crime scene will influence assumptions going forward. If another detective shares information about a suspect, it might lead the forensic scientist toward bias in the evaluation, interpretation, analysis, and conclusion of any evidence studied.
Cascading Bias
Exposure to information and materials related to a particular crime can demonstrably impact a scientist’s interpretation and thoughts regarding forensics. One mistaken impression can then cascade throughout other phases of the investigation. The failure to isolate information that individuals consider can lead to what is referred to as a bias snowball. That snowball can send biased reasoning throughout multiple phases and people involved in a case, resulting in the inadvertent effort to prove a particular theory.
rather than simply allowing the facts to lead to a conclusion. For instance, consider the impact of determining the relevance of a particular piece of evidence. It may be quite difficult to differentiate between items of significance and those of no import at all. Let’s say, for example, that a cigarette butt is found in the street near a dead body. Is it a piece of trash or a clue? Would knowing that the key suspect is not a smoker influence an examiner’s evaluation of the evidence? It is not far-fetched to believe that it could. When an examiner is responsible for both studying and integrating various lines of evidence, the chances for error in terms of cascading bias increase.
A Serious Problem
The issue of bias has been described by researchers as both pernicious and generally unrecognized by those in the criminal justice field. Truly, this puts into question the reliability of so-called expert witnesses who testify to forensic conclusions and makes one wonder why it is that these kinds of errors related to bias are not being aggressively addressed by the criminal justice community. Continue reading