Measurement as the Basis of Forensic Identification

Abstract

In the face of recurrent discussion on how "unscientific" most of forensic identification methods are, as well as numerous mistakes of courts in cases based on the opinions of experts, many scientists sees the solution to the problem in a broader application of identification methods based on the measurement. In the literature, there are even voices that only task of an expert should be to determine (measure) the level of convergence of the characteristics of objects, and not to conclude whether the trace comes from a particular person or object. Considering whether the measurement is the panacea for the ills of the forensic identification, it should be remembered that although it is possible now to measure more and more objects and to use very accurate measurement tools, the objectification of results by taking measurements are feasible only if the characteristics of the identified object are constant - and such situation is, in practice, extremely rare. So, while the idea of objectification of research results by replacing the subjective judgments of an expert with objective measurement results is, by itself, correct, its widespread use in forensic science is not very realistic. When examined features do not have the attribute of immutability, subjecting them to the exact measurements is not synonymous with making correct and useful in court findings. Divergence of outcomes of measurements does not have to mean that we have to deal with different objects, as well as compatibility of the results do not always mean identity (homogeneity) of identified objects. Typical example of such situations include the identification of a person based on handwriting or identification of tools based on the trace left by it. Pretense of objectivity by making measurements when, in view of the nature of the object being measured, it is not justified, may, according to the author, lead to more harm than benefit. In order to objectify many traditional methods of forensic identification, we should focus on elements other than the measurement (for example the frequency of the specific characteristics in the population) and remember that in the end "each expertise is only as good as an expert, who executes it".