Abstract:
In the previous part of this contribution I discussed the history of so-called
“demeanour evidence” and its current role in the law of evidence. I furthermore
examined the extensive empirical evidence that shows that demeanour – as a
means of accurate and reliable credibility assessment and decision-making in
litigation – essentially is worthless. Human lie detection is fraught with
difficulty. It is predicated upon a multitude of misconceptions about how liars
behave, including specific verbal and nonverbal cues commonly believed to
indicate dishonesty.
Below I continue with an analysis of the social science research data on
veracity judgments based on demeanour in order to attempt to answer the
question: Why are human beings such poor lie detectors? Next I expound upon
the reasons why lie detection in court might actually be more difficult than in a
laboratory setting. I then explore the potential impact of empirical findings upon
the principle of appellate deference to credibility findings of first instance. I
conclude by addressing the question regarding the appropriate response of the
legal system in the face of the overwhelming research data on the lack of
reliability of so-called “demeanour evidence”.
