The case for bifurcated trials: narrowing the odds of executing the innocent.

• Author: Balko, Radley
• Position: Columns - Column

LAST JULY, the Texas Forensic Science Commission found that arson investigators had used flawed science in the trial of Cameron Todd Willingham. Willingham was convicted of setting the 1999 fire that killed his three children. He was executed in 2004, despite serious questions about his guilt. The case garnered national attention last year after a David Grann investigation in The New Yorker argued that there was no evidence the fire was intentional.

Now another questionable arson-related death penalty case is percolating in Pennsylvania, where Daniel Dougherty sits on death row for setting the fire that killed his two sons in 1985. Arson experts John Lentini and Angelo Pisani have found that, in a situation similar to the Willingham case, fire investigators relied on outdated and disproved science. One of them, for example, testified that the extreme heat put out by the fire could only have come from the use of a liquid accelerant, an assertion that arson specialists today say simply isn't true. Accelerants have little to do with how hot a fire burns. Subsequent investigators have found no forensic evidence that the blaze that killed Dougherty's children was deliberate.

In Mississippi two men--Devin Bennett and Jeffrey Havard--today sit on death row for the murder of children in their care. Both men insist the deaths were accidents. Both were convicted mostly based on the testimony of the controversial medical examiner Steven Hayne, whose dubious record was the subject of an investigative feature I wrote for the October 2007 issue of reason. In both cases, more reputable medical examiners who later reviewed Hayne's work reported that the signs of abuse he claimed to have found simply aren't there.

In recent years, DNA testing has exposed some serious flaws in several fields of forensic science. A 2009 National Academy of Sciences report found that forensic specialists often make exaggerated claims in the courtroom, expressing levels of certainty that aren't always supported by scientific research. In cases where it's certain that a crime was committed and for which DNA is available for testing, the challenge is getting prosecutors to agree to the tests. But in cases like that of Dougherty, Willingham, Bennett, Havard, and others, the question isn't who committed the crime, but whether a crime was committed in the first place.

DNA isn't of much use in those cases. But during a panel discussion at the Georgetown Law Center last year...