As a lawyer, determining whether a witness is a liar is incredibly important.

An experienced lawyer, and by that I mean someone who has spent many years in the courtroom and in depositions, may be able to intuit better than a layperson who is and who is not lying, but it would be helpful to have something more objective and scientific than intuition. Experience and cross examination are helpful, but is there more?


The June 2017 issue of National Geographic was entitled “Why We Lie”. The research quoted in the article found that people tell lies for many reasons:

  • Personal transgression (cover up of a mistake or misdeed) – 22%
  • Economic advantage – 16%
  • Personal advantage – 15%
  • Avoidance (escape or evade people) – 14%
  • Self-impression (shape a positive image of ourselves) – 8%
  • Unknown – 7%
  • Humor – 5%
  • Altruistic (help people) – 5%
  • Malicious – 4%
  • Pathological – 2%
  • Social of polite – 2%

The article comes to the conclusion that people lie and tell the truth to achieve a goal. According to researcher Tim Levine, “We lie if honesty won’t work.”

Another interesting fact, according to psychologist Bruno Verschuere, is that “The truth comes naturally, but lying takes effort and a sharp, flexible mind.”

That is why very small children tend to tell the truth. Children learn to lie between ages 2 and 5, and lie most when they are testing their independence.

This guidance is helpful because it teaches us to examine possible motives, but it is obviously true that not all people always tell a lie even if there is a hypothetical motive to lie or negative consequences if they tell the truth.

Are more clues available?

There are researchers who believe they can predict deception by closely examining linguistic styles. Researchers at the University of Texas at Austin, Southern Methodist University and the University of Washington have studied how people write or talk about personal topics. Their study was published in Personality and Social Psychology Bulletin, 29, 665-675, 2003. They analyzed the “language of truthfulness versus deception.”

The researchers analyzed language using a computer-based text analysis program and human judges.

The researchers concluded that “liars tend to tell stories that are less complex, less self-relevant, and more characterized by negativity. At a broad level, the differences between deceptive and truthful communications… are consistent with the idea that liars and truth-tellers communicate in qualitatively different ways. Consequently, the present studies suggest that liars can be reliably identified by their words – not by what they say but how they say it.”

The computer-based technology correctly decided whether a person’s story was truthful 67% of the time. The human judges were correct only 52% of the time.

To my knowledge, there are no studies which evaluate the accuracy of juries in evaluating the truthfulness of witnesses.

If you believe in the “wisdom of the crowd” (collective judgment) and if you believe that the crucible of the courtroom and cross examination tend to reveal the truth, then you will probably conclude that trials usually arrive at a just result, but there is obviously room to doubt.

What can be said is that humans have devised no better system than a trial before a jury conducted by a competent judge with both parties represented by able lawyers.