法证科学领域的决策

随着法证DNA证据以及它所适用的概率模型日益凸显,反映了传统法证科学的局限性,并使人们对法证科学领域的决策产生了越来越多的质疑,焦点集中在对结论的解读方式和实际运用。分析表明,科学证据的本质不是绝对性或确定性的,而是概率性的;同时,事实审判者需要基于这些概率性的证据对事实作出明确的决定。因此,对于法证科学领域的决策,应当是专家在一系列归纳得出的特定假设基础上,就研究结果的概率进行恰当的报告,由事实审判者承担对概率作出决断的任务。

Decision-making in the Forensic Arena.

In the real world,forensic science is increasingly criticized for its lack of a scientific basis,as much of what passes for forensic science does not on closer examination qualify as science.As a result of the growing prominence of the scientific paradigm associated with DNA evidence,traditional identification science is now lying heavily under siege.Any statement of the probability of a particular source attribution hypothesis necessarily involves two elements:the probability of the evidence under two competing hypotheses and an estimate of the prior probability of the hypothesis,i.e.,the probability of the source attribution hypothesis before the scientific evidence becomes available.Forensic scientists should not be allowed or take it upon themselves to usurp the role of the judge but should always be aware that the role of the expert is to pronounce upon the weight of the forensic evidence,not to address the ultimate issue.Unlike traditional reporting formats,the model used in the interpretation of DNA evidence is ideally suited to do just that:it forces the expert to report on the probability of the findings under a particular set of hypotheses and leaves the determination of the probability of the(prosecution) hypothesis to the trier of fact.