First NIST OSAC Forensic Science Standards Up for Public Comment

One of the responses to the 2009 NRC report on forensic science was the creation last year of an Organization of Scientific Area Committees (OSAC) for forensic science organized by the National Institute of Standards and Technology (NIST). This organization is developing new standards for forensic disciplines to follow.

Last week, NIST opened a 30-day public comment period for five standards from the Chemistry Scientific Area Committee. They are continuations or updates of existing ASTM (American Society of Testing and Materials) standards. The NIST OSAC News Release on the public comment period is at http://www.nist.gov/forensics/osac/osac-opens-public-comment.cfm. The five standards under consideration for inclusion on the OSAC Registry of Approved Standards are as follows:

• ASTM E2329-14 Standard Practice for Identification of Seized Drugs
• ASTM E2330-12 Standard Test Method for Determination of Concentrations of Elements in Glass Samples Using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for Forensic Comparisons
• ASTM E2548-11e1 Standard Guide for Sampling Seized Drugs for Qualitative and Quantitative Analysis
• ASTM E2881-13e1 Standard Test Method for Extraction and Derivatization of Vegetable Oils and Fats from Fire Debris and Liquid Samples with Analysis by Gas Chromatography-Mass Spectrometry
• ASTM E2926-13 Standard Test Method for Forensic Comparison of Glass Using Micro X-ray Fluorescence (µ-XRF) Spectrometry

Although they may seem technical and have forbidding names, some of these proposed standards should be of interest to lawyers as well as forensic scientists and statisticians who might want them to address how findings should be presented in court or in reports. For example, one standard involving glass fragments requires a difference of 3 standard deviations before the analyst can reject the hypothesis that the fragments on the suspect came from the crime scene. But 2.9 usually would be pretty good evidence that the suspect's fragments are from some other glass. What should the standard require or allow an expert to report in cases like this, where the suspect's fragments lie within the broad window for measurement error? Should there be an adjustment to the rejection range if more than one fragment has been tested? Should there even be a fixed window, or should the analyst simply report the probability of differences in the measurements as or more extreme as those observed if the fragments on the suspect came from the crime-scene glass? Better still, can a likelihood ratio be provided?

It appears that this 30-day period also offers an opportunity to view related ASTM standards on forensic science tests. Normally, ASTM, as the copyright holder, does not make its standards freely available.

Directions for subscribing to the OSAC newsletter and receiving announcements of comment periods, new standards, etc., are at the above URL and at http://www.nist.gov/forensics/osac/osac-launches-monthly-newsletter.cfm.

Disclosure and disclaimer: Although I am a member of the Legal Resource Committee of OSAC, the views expressed here (to the extent I have expressed any) are mine alone. They are not those of any organization. They are not necessarily shared by anyone inside (or outside) of NIST, OSAC, any SAC, any OSAC Task Force, or anyone else in the Legal Resource Committee.

Posted by siska ika

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