Comment les juges détectent-ils les mensonges lors de procès? Étude des mécanismes communicationnels sous-jacents aux déclarations de culpabilité pour parjure

Both in criminal law trials and in administrative, civil or family law trials, deception can lead to the development of narrative patterns that obscure facts that judges should know in order to properly apply the law. In addition, if judges are unable to distinguish truth from falsehood in testimonies, the public trust essential to the proper functioning of the justice system may be compromised. Furthermore, even if researchers have, since the 1960s, been interested in detecting deception, especially during police interrogations conducted in laboratories, these experiments ignore several attributes of adversarial justice systems (e.g., court proceedings, incriminating evidences, sworn statements, examinations, cross-examinations and pleadings). As a result, since the detection of deceptive testimony by judges during trials is hardly ever addressed, judges in municipal, provincial and federal courts are practically left on their own. In my thesis, I present a descriptive, analytical and explanatory work to observe and better understand the reasoning, or at least part of the reasoning, by which judges, in a natural setting, have come to determine, from their perspective, that witnesses have lied while testifying. This research aims, among other things, to improve the ecological validity of laboratory experiments and to address more adequately the problem of deception during trials. On the one hand, in order to study the detection of deception in the actual context in which it takes place rather than in the context of an experimental representation of this activity, I have chosen to turn to written judgments of Canadian courts as research data, more specifically, four Canadian judgments pertaining to a criminal charge of perjury resulting from an incriminating statement in which the accused was found guilty. On the other hand, in order to describe, analyze and explain in a thorough and in-depth manner the underlying communicative mechanisms of perjury convictions, I have chosen to use a contemporary approach to discourse analysis that is part of the work of the Montreal School—the ventriloquist approach to communication (Cooren, 2013)—to the extent that this approach allows to identify the elements that appear to make a difference in the constitution of a judgment. Aside from the alarming scarcity of judgments rendered following trials on a criminal charge of perjury resulting from a testimony, the results of my analyses make it possible to observe the substantial role of popular beliefs and the considerable contribution of precedents in the judges’ decision-making process during trials. As demonstrated in my thesis, these popular beliefs may expose assumptions about human behaviour conveyed or expressed, explicitly or not, by judges in their judgments. As for precedents, they may have the effect of veiling the substantial role of these very beliefs in the judges’ decision-making process. Furthermore, the results of my analyses suggest that the detection of deceptive testimony by judges during trials depends, among other things, on several contextual elements as staged in the judges’ reasoning and has little to do with the typical experimental design set up for studying deception detection. Finally, although they do not offer a “new technique” for distinguishing the honest litigant from the liar, the results of my analyses are consistent with other research that demonstrates the a priori limited usefulness of behavioural indicators of deception and suggests that legal practitioners, particularly judges, should be systematically trained on the fallible nature of the decision-making process during trials.

Keyphrases: Trials, witnesses, perjury, deception detection, ventriloquism, Montreal School