Problems With Forensic Expert Testimony in Arson Cases

by Becky Huting, UMN Law Student, MJLST Staff

In MJLST Volume 14, Issue 2, Rachel Diasco-Villa explored the evidentiary standard for arson investigation. Ms. Diasco-Villa, a lecturer at the School of Criminology and Criminal Justice at Griffith University, examined the history of arson-investigation knowledge, and how the manner in which it is conveyed in court can mislead, possibly leading to faulty conclusions and wrongful convictions. The article discussed the case of Todd Willingham, who was convicted and sentenced to death for setting fire to his home and killing his three children. Willingham had filed numerous unsuccessful appeals and petitions for clemency, and several years after his execution, a commission’s investigation concluded that there were several alternative explanations as to the cause of the fire, and that neither the investigation nor the evidence testimony were compliant with existing standards.

During the trial, the prosecutor’s fire expert, a Deputy Fire Marshall from the State Fire Marshall’s Office, testified as to why he believed the fire was set by arson. Little science was used in his explanation:

Heat rises. In the winter time when you are going to the bathroom and you don’t have any carpet on the rug. . .the floor is colder than the ceiling. It always is. . . So when I found that floor is hotter than the ceiling, that’s backwards, upside down. . .The only reason that the floor is hotter is because there was an accelerant. That’s the difference. Man made it hotter or woman or whatever.

The expert went on to explain that fire investigations and fire dynamics are logical and common sense, such that jurors themselves could evaluate with their sense and experiences to arrive at the same conclusions. All samples taken from “suspicious” areas of the house tested negative for any traces of an accelerant. The expert explained the chemical results: “And so there won’t be any — anything left; it will burn up.”

Fire and arson investigation has traditionally been experiential knowledge, passed down from mentors to their apprentices without experimental or scientific testing to validate their claims. Fire investigators do not necessarily have scientific training, nor is it necessary for them to hold a higher educational degree beyond a high school diploma. The National Academy of Science released a report in 2009 stating that the forensic sciences needed standardized reporting of their findings and testimony, and fire and arson investigation was no exception. The International Association of Arson Investigators has pushed back on such guidance, having filed an amicus brief arguing that arson investigation is experience-based and not novel or scientific, so it should not be subjected to higher evidentiary standards. This argument failed to convince the court, which ruled that fire investigation expertise should be subject to scrutiny under the Daubert standards that call for exacting measures of reliability.

Ms. Diasco-Villa’s note also considers the risk of contextual bias and overreach, should these experts’ testimony be admitted. In the Willingham case, the expert was given wide latitude as to his opinion on the defendant’s guilt or innocence. He was allowed to testify as to his belief that the suspect’s intent “was to kill the little girls” and identify the defendant by name as the individual who started the fire. Under Federal Rules of Evidence section 702, expert witnesses are given a certain degree of latitude in stating their opinions, but the author was concerned with the risk of jurors giving extra weight to this arguably overreaching testimony by expert witnesses.

She concluded by presenting statistics concerning the vast number of fires in the United States each year (1.6 million), and the significant quantity that are classified as having been intentionally set (43,000). There is a very real potential that thousands of arrests and convictions each year may have relied on overreaching testimony or evidence collected and interpreted using a defunct methodology. This state of affairs in arson investigations warrants continued improvements in forensic science techniques and evidentiary standards.