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Propositions — key to the evaluation process

One of the key elements in the logical approach to evidence evaluation are the propositions used for the evaluation. They are, in a certain sense, the most important part of the whole process. At the same time, they are also one of the least understood.

Today’s post explores the concept of propositions. I will attempt to describe what they are, how they are used, why we don’t change them once set and why they matter so much, among other things… all from the perspective of forensic document examination (though also applicable to other forensic disciplines).

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Forewarned…

Forewarned is forearmed or, if Latin is your thing, “praemonitus, praemunitus”. So the saying goes and clearly there is great value in knowing what lies ahead for us. If we know what is coming our way we can, in theory, prepare properly for any challenge.

Challenges are nothing new to forensic scientists. Critics routinely point out issues they have with our work. Some of those criticisms are fair and reasonable, others not so much. Much of the critical commentary affects a discipline as a whole demanding an overall, or group, response by members of each discipline. In my experience, disciplines tend to be behind the curve in their responses to critics. Nonetheless, over time some issues have been addressed, at least partially if not completely, through empirical research. Others have not. To be fair, the activities needed to properly address the critics are not trivial and require both time and resources; scarce commodities in modern forensic labs. Overall, things are improving, albeit very slowly.

Criticism takes on a whole new meaning in the context of a court of law. Indeed, I think that criticism is the essence of cross-examination — a fundamental and important aspect of any adversarial justice system. Although essential, it is rarely an enjoyable part of the proceedings for any expert.

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Certification — ABFDE

What is certification? In my opinion, professional certification is a designation that indicates the holder of the certification has appropriate and adequate qualifications to do some particular, generally well-defined, job or task. As an example I am a forensic document examiner and I have received professional certification from the American Board of Forensic Document Examiners, Inc.

An internet search for ‘certification’ produces a huge list of possibilities, with more such programs being developed all the time as people become attuned to issues of quality and competency. Indeed, almost every profession has some type of certification and a few have several (consider all of the ‘certifications’ in the computing industry). Most, if not all, certification programs are aimed at improving the quality in a given profession by setting minimum standards for the job. The basic idea is that someone meeting or exceeding those standards will produce quality output on the job. Certification programs are generally created or are administered by a professional society, a college or university, or some private body set up expressly for that purpose.

Forensic Document Examination is no exception so it may be worthwhile discussing certification options as well as the pros and cons that I see for those options.

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The ‘best’ textbook ever written about forensic handwriting identification…

Huber and Headrick Handwriting Identification

Okay, determining the ‘best’ of anything is always a challenge. It is, in almost every instance, a highly subjective decision based on some set of appealing features or characteristics… appealing to the person making the determination, of course. And, because this is my blog, that person happens to be me. In fairness, there are a number of authors who have written extensively on the topic: Osborn, Ellen, Hilton, Harrison, Hilton, among others (and I apologize to those I have left off this list). I have read all of those textbooks (including most editions) and each has its strengths and weaknesses. Nonetheless, in my opinion the best general textbook written to date on the topic of handwriting identification was done by co-authors Roy A. Huber and A.M. (Tom) Headrick, both long-time document examiners in the R.C.M. Police laboratory system.

That textbook is Handwriting Identification: Facts and Fundamentals.1Read more

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Can of worms…

Worms in a can

When someone “opens a can of worms” it usually spells trouble. For many people, that phrase evokes a powerful image of a writhing mess of worms escaping from a previously-sealed, but now opened, can or container. With the result of such action being serious problems for the owner of said can, often problems of an unanticipated or uncertain nature. In the context of our work as Forensic Document Examiners, I sometimes hear this coming up in discussions of how to handle questions on the stand. The advice goes along the lines of ‘keep your answers simple and say as little as possible in order to limit any opportunity for questions from the other side.’

It is suggested that lengthy or complex answers will only lead to more questions and more discussion. The latter are the proverbial “can of worms” that one must strive to avoid opening.

That makes little sense to me.

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2014 ASQDE-ASFDE Panel Discussion “Conclusions…”

The 2014 ASQDE–ASFDE conference included an interesting panel discussion with the title “Conclusions… Signature and Handwriting Conclusion Terminology and Scales”. I was fortunate to be able to take part, albeit only remotely via Skype.

ASQDE ASFDE logos

 

The abstract for the session was as follows:

A current and global issue in our field is the topic of conclusion terminology and conclusion scales, particularly in respect of signature and handwriting conclusions. It is an important yet difficult topic to address because, while there is some commonality in the conclusion scales used in different geographical regions around the world, within a number of geographical regions there are multiple scales in use. It is for this very reason that it is also a topic in great need of discussion and there is a strong argument that we should attempt to reach a consensus (even if the result is that we agree to disagree).

This panel discussion is a collaboration of insights from numerous colleagues in our field in person, via Skype and in writing from private and government laboratories in geographical regions across the Americas, Australia, Asia, Africa, the Middle East and Europe.
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R. v. Mohan — Canada’s Daubert?

It is safe to say that pretty much everyone working in the forensic sciences has heard of the Daubert ruling or, more specifically, Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993).1 It was a pivotal ruling that, together with two subsequent rulings General Electric Co. v Joiner, 522 U.S. 136 (1997)2 and Kumho Tire Co., Ltd. v Carmichael, 526 U.S. 137 (1999),3 has greatly affected many legal jurisdictions in the United States. And, as is often the case, whatever happens in the USA tends to have influence elsewhere.

R. v. Mohan — Canada's Daubert

Shortly after that, in Canada, there was a key Supreme Court ruling that addressed admissibility of forensic expertise — R. v. Mohan, [1994] 2 S.C.R. 9.4

That ruling laid out the test for the admissibility of ‘novel’ expert evidence (see Mohan, page 4) in Canada.

Subsequently, the factors explained in that ruling have been applied, just as those in Daubert were, to many types of traditional forensic science evidence. It is, perhaps, rather ironic that rulings intended to liberalize the admission of new (and potentially) helpful evidence would lead to challenges of all forms and types of evidence.

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ICFIS 2014 — Teaching the Logical Approach for Evidence Evaluation to FDEs

This year’s International Conference on Forensic Inference and Statistics (ICFIS) is being held at Leiden University in the Netherlands.  ICFIS 2014 logoICFIS conferences are always very good and this is the 9th such event.  I am hoping to attend to present my thoughts on the topic of education relating to the logical (a.k.a. likelihood-ratio or LR) approach to evidence evaluation. Over the last few years I have given several one and two-day seminars and workshops on this topic, mainly for Forensic Document Examiners (FDEs) though the subject matter relates to all disciplines equally.  Those workshops have been great and provided a relatively unusual opportunity to learn about how fully trained examiners come to grips with a complicated and difficult topic.  One that is fundamental to FDE work.
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Tobin Tanaka at the CIS conference, Richmond BC

My colleague and fellow document examiner, Tobin Tanaka, is giving a presentation about Forensic Document Examination at the Canadian Identification Society (CIS) Annual Educational Conference at the River Rock Casino in lovely Richmond, BC.

A full review of the conference will be provided at some time in the future but, for now, Tobin has asked me to provide links to his presentations so that attendees have access to his talk in electronic format.

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Statistics — Worse than a lie

It has oft been said that “there are three kinds of lies: lies, damned lies and statistics”.  That phrase, according to Mark Twain, came from Benjamin Disraeli. Interestingly, it has never been found in Disraeli’s written works so that attribution is likely incorrect.

A lie, perhaps, by Twain?

Lies - Mallett

But I digress.  The source of the statement doesn’t really matter.  It is enough that the phrase reflects the belief that many people have when they think about statistics.1

It is a catchy little phrase.  Yet most reasonable people know that numbers — and statistics are simply numbers after all — cannot do anything on their own.  Hence, statistics can no more lie than they can sing or dance.

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