But doesn’t that mean it is ‘more likely than not’?

When an examiner expresses an opinion along the lines of ‘the findings support one proposition over another proposition’, a question often follows. Specifically, does that opinion mean ‘it is more likely than not that the favored proposition actually happened’?1 The short answer is “no, it does not mean that.” At least, not necessarily.

In order to reach such a conclusion one must consider information that goes beyond the FDE evidence. As a rule, any opinion I provide will be constrained to the probability of the findings/observations in terms of one of at least two possible explanations.2 Ultimately, equating the two statements is inappropriate because they are not equivalent.

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CSFS Position paper on the Logical Approach

I recently published an editorial in the Journal of the Canadian Society of Forensic Science.  Two versions were published almost simultaneously (the original written in English and a translation in French) entitled, respectively, “CSFS Document Section Position on the Logical Approach to Evidence Evaluation and Corresponding Wording of Conclusions” and “La position de la Section des documents de la SCSJ sur l’approche logique de l’évaluation de la preuve et le libellé des conclusions”.

I wrote these in my capacity as the sitting chairman of the Documents section of the CSFS, on behalf of the members of that section.  The impetus for writing them was to introduce the “logical approach” and related topics to the Canadian forensic community in a ‘formal’ way (hopefully resulting in ongoing discussion) and to provide the public and the courts with the perspective of forensic practitioners who have reviewed the literature and studied this issue in depth. To that end, the document references many initiatives relating to the topic. I will note that it’s not a perfect document but it covers the main points reasonably well.

Please note that this position paper was first written a few years ago.  There was considerable delay in publication relating to the production of an acceptable French-language translation of the document. I must thank Julie Binette who was invaluable in that process. The delay, however, means the references provided in the paper are not fully up-to-date with the very latest developments in this area.

Nonetheless, that shortcoming doesn’t detract from the position expressed.  Today there is even more support and justification than is outlined in the paper. 

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CSFS 2018 Conference

The Canadian Society of Forensic Science (CSFS) is holding its 2018 conference and AGM in Gatineau, QC. I’m happy about that because it’s in my own backyard, so to speak.

CSFS conferences vary in their quality and content but this year is looking pretty good.  For example,  the keynote speaker is Dr. Claude Roux whose presentation is entitled ‘Will Forensic Science Reach the End of the Crossroads Soon?’  That’s a tremendous question.  How would you answer it?  Dr. Roux is sure to have an interesting perspective to share with us.  Read more