EVIDENTIAL VALUE OF HAIRS AND REPORT WRITING

• Jurisdiction: Australia

Nomenclature and language......................................................................... [88B.700]

Role of DNA analysis .................................................................................... [88B.720]

Daubert, Bayes and beyond ......................................................................... [88B.740]

[88B.700] Nomenclature and language

The late Jim Crocker (1991) stated that "the greatest challenge faced by forensic hair examiners is to be able to leave the witness box with a feeling of assurance that members of a jury, or a judge acting alone, have the same appreciation as the examiner of the proper level of significance to be given to hair evidence".

Arguably it is the responsibility of the forensic scientist to go further and define what hair "evidence" does not say and its boundaries and limitations. The scientist's formal report plays an important role in meeting the aim put forward by Crocker.

The underlying principle which should govern the approach of the hair examiner is that the fundamental hypothesis should be to attempt to exclude an individual or individuals as the donor of recovered or questioned hairs. The language used should reflect this principle. Hence, in the author's opinion, the use of terms such as "similar" and "consistent" is inappropriate in the hair examiner's vocabulary. Recent draft reporting guidelines from the US National Institute of Justice regrettably still recommend the use of "similarities" and "dissimilarities" (2016).

Crocker (1991) discussed the results of a study to interpret forensic science phraseology. The approach used was to assess the weight placed, by jurors and criminal law professionals, on a series of statements. From the results of this study, the term "consistent with" was considered positive (certain) by 42% of jurors and positive (probable) by 35% of jurors. Eighteen per cent of jurors thought it meant "possible". Professionals were more conservative, with 38% indicating positive (probable) and 62% possible. The term "could have" was taken by 100% of professionals to mean possible; only one juror felt it meant positive (certain) and 6% of jurors positive (probable).

The critical message which should be clear from this study is that whatever terminology is used by a particular laboratory or an individual, the report (if it is to be meaningful and not potentially misleading) must attempt to spell out what weight or significance is or should be attached to the terms used.

If the principle of exclusion is accepted, then hair reports should be written from a perspective of what they can say with some certainty, that is, a particular (questioned) hair could not have come from a particular individual. Even here caution needs to be exercised, as there may be factors which do not allow even this "strong negative" conclusion. If it is not possible to exclude a nominated individual as the donor of a questioned hair, the examiner must then attempt to assess the weight and significance which ought properly to be placed on that finding.

The term "consistent with" should be rejected, and at least two major commissions of inquiry (Kaufman, 1998; Shannan, 1984) into wrongful convictions have criticised the use of this term in the strongest possible way. Shannan states that "it seems to me that the use by...