Is the Expert Admissibility Game Fixed?: Judicial Gatekeeping of Fire and Arson Evidence

Anecdotal evidence claims that in criminal cases, trial judges admit the prosecution's expert witnesses more readily than the defendants', and in civil cases the reverse is true; judges exclude plaintiffs' experts more often than civil defendants' experts. This occurs despite the fact that, with few exceptions, the same rules of admissibility apply to all parties and, in most jurisdictions, across criminal and civil cases. This article empirically tests this differential by reviewing judicial decisions to admit or exclude evidence holding the type of expert testimony constant, fire and arson evidence, across criminal and civil cases in the United States. The study examines the admissibility of fire and arson investigation experts in criminal and civil cases across all legal parties in fifty-seven federal and state opinions in the United States. The findings offer empirical support of a bias in criminal cases and in civil cases which present expert witnesses at trial, and is less pronounced, but still evident, on appeal. Specifically, the role of the party that offers the evidence has a profound effect on whether arson evidence is admitted, even when factors around the judge's political affiliation, attorney experience, expert qualifications, and rules of evidence are taken into account.