Eying the Body: The Impact of Classical Rules for Demeanor Credibility, Bias, and the Need to Blind Legal Decision Makers

Abstract

To detect lies, people can scrutinize a speaker's body language or flip a coin. The results are about equally reliable. The justice system has known this 25 years, but demeanor credibility remains critical in legal outcomes. Work on cognitive and implicit bias has reinforced skepticism. Why has nothing changed?

One reason is the unacknowledged influence of classical rhetoric, until recently the heart of Western education. Today, ancient rules for credibility and assumptions about truth, rationality, and a universal language of non-verbal communication continue to be taught in law schools and enforced in courts. Together, they reconcile the professional claims of highly trained advocates with the trial as a search for truth.

This system imposes profound risks, particularly on individuals with non-elite demeanor. Improved instruction may help. Another solution, blinding, is increasingly common to support proper decision making. It would require screening judge and jury. Such blindfolded justice imposes appropriate humility about the limits of rationality, including our own.

Keywords: rhetoric, demeanor, demeanor credibility, evidence, delivery, non verbal communication, body language, legal education, contempt