Issues in Explosive Residue Analysis: Daubert provides guidance and a means to expose limitations and evaluate explosive investigations, methods, and interpretation

Issues in Explosives Residue Analysis A Primer for the Bar Frederic Whitehurst, Ph.D.[1]

[Editor’s Note: This is a multi-part series deigned to educate the defense bar on important issues concerning explosive and explosive residue investigations]

Part 1: Introduction

Part 2: Back to the Basics: Was it the result of an explosive device in the first place? How do we know that?

Part 3: Daubert provides guidance and a means to expose limitations and evaluate explosive investigations, methods, and interpretation

Part 4: The Explosion Crime Scene: Sampling and Homogeneity Issues

Part 5: Disposition Homogeneity in explosive scene investigation

Part 6: Contamination and Cross Contamination in explosive scene investigation

Part 7: Contamination by “Render-Safe” acts of explosives

Part 8: Transportation and storage of evidence in explosive scene investigation

Part 9: Chemical analysis in explosive scene investigation

Part 10: Identifying Techniques in explosive scene investigation

Part 11: Interpretation of data in explosive scene investigation

Part 12: Experience: What makes for a proper expert in explosive scene investigation?

Part 13: Conclusion

Within the parameters described earlier in this paper, the scientist must decide the limits of the interpretation of the data. Despite the complexity of the problem, however, there is now a guide which can be followed in addressing this problem. That guide comes to us from Daubert v. Merrell Dow Pharmaceuticals, Inc. [17] Those scientists that might scoff at the idea of learned men of law dictating protocols to men of science especially in such a complex area as explosives residue analysis might be surprised to realize that this rule was informed by a variety of perspectives from the scientific community as expressed in twenty-two amicus briefs. [18]These briefs were presented by recognized authorities in science to include the American Association for the Advancement of Science and the National Academy of Sciences as well as individual scientists. [19]If forensic scientists must ultimately satisfy the needs of the court system, this is an admirable guide to give them the direction they need. Possibly without realizing it, the Supreme Court in Daubert has given the forensic scientist at once a guide as well as the freedom to dynamically address the problem before them free of the strict confines of the superseded requirements of the Frye test of “general acceptance.” [20]

The criminal/terrorist bomber is an extremely dynamic target and demands the quick investigative response not allowed by strict adherence to these cumbersome “general acceptance” requirements. Without the requirements of publication and/or general acceptance in the scientific community as the sine qua non of admissibility of expert testimony, forensic explosives analysts, who are very few in number and overburdened with the task of analysis, do not have to see their scientific credibility in court unequivocally impeached for lack of publications and extensive peer review. The court has, by this decision, made this analyst much more dynamic and effective against terrorism.

Along with the release from unnecessary burden, however, the new protocol has brought responsibilities to the science obviously defined in amicus briefs by the scientific community itself. Those responsibilities define parameters within which the science will be conducted and give definite controls over the interpretation of data and presentation of opinions. As pointed out in Wilson [21] “the consequences of this liberality is not, or at least should not be, a free-for-all. The elimination of formal barriers to expert testimony has merely shifted to the trial judge the responsibility of keeping ‘junk science’ out of the court room.” Daubert requires that the Frye rule be superseded by the Federal Rules of Evidence.

Beginning with Rule 402 as the “baseline” [22], Daubert defines “relevant evidence” as “that which has ‘any tendency to make the existence of any fact that is of consequence to the determination of the action more probable or less probable than it would be without the evidence.'[23]Daubert goes further then to quote Rule 702 governing expert testimony; “If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise…. The subject of an expert’s testimony must be scientific knowledge…. The word ‘knowledge’ connotes more than subjective belief or unsupported speculation. The term applies to any body of known facts or to any body of ideas inferred from such facts or accepted as truths on good grounds…. To qualify as ‘scientific knowledge’ an inference or assertion must be derived by the scientific method. Proposed testimony must be supported by appropriate validation… based on what is known.” Quoting from Weinstein and Berger [24]Daubert notes that “Expert testimony which does not relate to any issue in the case is not relevant and, ergo, nonhelpful.

Following the guidelines set out in Daubert this paper will explore issues in the development of protocols for analyses and possible interpretations of data and hopefully will more fully educate the bar and the court to be able to ask appropriately probing questions of the expert in explosives residue analysis. As the court is the ultimate quality assurance and quality control mechanism for the forensic scientist, this paper should also sharpen those functions with an understanding of underlying issues. The aim of the paper will be to educate the court in this particular area of forensic science in order to ensure that “The trier of fact should have all relevant investigative data available, and not just what is beneficial to one party.” [25].

This paper will be divided into discussions of the various aspects of the “chemical” investigation of explosives crime scenes. The direction will rely on and quote the various requirements established by Daubert where they are appropriate guides. Starting with sampling and transportation of evidence, the paper will then proceed to issues in instrumental analysis and interpretation of data gleaned from those analyses. The paper will also address the definition of “explosives expert” noting the many types of specialized skills required to successfully analyze a bombing crime scene.


[1] Executive Director, Forensic Justice Project, Washington, D.C., B.S. Chemistry, 1974, East Carolina University, Ph.D. in Chemistry, 1980, Duke University, J.D., 1996, Georgetown University School of Law. (202)342-6980.

[17] Daubert v. Merrill Dow Pharmaceuticals, Inc., 113 S.Ct.2786 (1993).

[18] Id. at 2799. Rehnquists notes in his dissent that the “various briefs filed in this case are markedly different from typical briefs, in that … they deal with definitions of scientific knowledge, scientific method, scientific validity and peer review.”

[19] Id. at 2795.

[20] Frye v. United States, 54 App.D.C. 46 (1923), required that expert opinion based on a scientific technique is inadmissible unless that technique is generally accepted asreliable in the relevant scientific community.

[21] Wilson v. City of Chicago, 6 F.3d 1233 1238 (1993).

[22] Rule 402, Federal Rules of Evidence: “All relevant evidence is admissible, except as otherwise provided by the Constitution of the United States, by Act of Congress, by these rules, or by other rules prescribed by the Supreme Court pursuant to statutory authority. Evidence which is not relevant is not admissible.”

[23] Daubert, supra note 17, at 2794.

[24] Daubert, supra note 17, at 2795, quoting from 3 Weinsteinand Berger 702(02), at 702-718.

[25] Editorial comment, Forensic Science Committee, 45 Fire And Arson Investigator (1994).

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