There is a lot that one can read at this blog about what is wrong with forensic science, but there are also great efforts to reform and make forensic science better and scientific. As I stated a long time ago when I started this blog, I was going to be critical of those disciplines and people that are not scientific, but I was also going to praise those who are. One of the best organizations that is doing the correct thing (putting science back into forensic science) is the National Fire Protection Association (NFPA). In my opinion, NFPA is a model for forensic science reform.
As we discussed here in Fire Whisperers-the Story of Bad Arson Investigation, the world of fire investigation had been notoriously full of unscientific “fire whisperers,” those who had no real scientific training and simply opined as to origin and cause of a fire based upon subjective and purely wildly speculative means. Unfortunately there are many jurisdictions that still employ these non-scientific “fire whisperers.”
After great struggle, NFPA formed a committee to promulgate a document that would force fire and explosive investigations to be more scientific. This resulted in NFPA 921, Guide for Fire and Explosion Investigations. It is universally hailed as the industry standard. (A brief discussion of the history and the background of NFPA 921 can be found at the www.NAFI921.com website.)
The latest version of NFPA 921 has been published just this month. In the 2011, we find the last vestiges of the “fire whisper” abolished: negative corpus. For years, the false methodology and the illogical basis to support a negative corpus conclusion as far as origin and source had been well exposed (See The Pitfalls, Perils and Reasoning Fallacies of Determining the Fire Cause in the Absence of Proof: The Negative Corpus Methodology By Dennis Smith and in Dr. Gerald Hurst’s opinion letter regarding the Terri Hinson case-March 16, 1998). However, it is only with this most recent document NFPA 921:2011 that we see direct language that addresses this. The document reads in short regarding Negative Corpus NFPA 921-18.6.5
The process of determining the ignition source for a fire, by eliminating all ignition sources found, known, or believed to have been present in the area of origin, and then claiming such methodology is proof of an ignition source for which there is no evidence of its existence, is referred to by some investigators as “negative corpus.” Negative corpus has typically been used in classifying fires as incendiary, although the process has been used to characterized fire classified as accidental. This process is not consistent with the Scientific Method, is inappropriate, and should not be used because it generates un-testable hypotheses, and may result in incorrect determinations of the ignition source and first fuel ignited. Any hypothesis formulated for the casual factors (e.g., first fuel, ignition source, and ignition sequence), must be based on facts. Those facts are derived from evidence, observations, calculations, experiments, and the laws of science. Speculative information cannot be included in the analysis.
I say let us all take a minute and praise NFPA and the arson community for doing the right thing and putting science back into forensic science!