What is a Human Factors Expert in a Criminal Case?

March 31, 2022 Criminal Defense

Human factors is a science that asks the age-old question – why do people do what they do? Human factor expert witnesses can come from a variety of backgrounds and serve the same purpose as every other expert retained in a criminal trial, to assist the trier of fact in reaching a decision. Now you may be thinking, how can there be an expert on this? This blog will explore the science behind human factor experts, their qualifications, and the overall role they play in a criminal proceeding

The Science Behind the Expert

Human factors is an established science that examines the relationship between human beings and the systems in which they interact. More specifically, human factors is a science that studies how humans interact with the environments, products, machines, and equipment around them.  Experts in human factors study the “effects of people’s mental, perceptual, and physical capabilities and limitations on these interactions.” Therefore, human factors experts use many disciplines, such as architecture, engineering, anatomy, physics, and biomechanics, and work alongside experts in those fields to understand how people behave under different circumstances.

Interesting History Behind the Discipline

The discipline of human factors originated in the United States during World War II out of military necessity. Initially, when World War I began, a need arose for methods to quickly select and train qualified pilots to employ the newly invented airplane in combat. This need continued and exponentially grew through World War II, a time where “technological advances had finally outpaced the ability of people to adapt and compensate to poor designs [which] was most evident in airplane crashes by highly trained pilots due to problems with control configurations.” As a result, the focus switched from “designing the human to fit the machine (trial and error), [to] designing machines to fit the human.” Military-sponsored research centered around human factors continued throughout the two decades following World War II, driven by the Cold War.

Why Are They Hired in a Criminal Case?

A human factors expert witness may be utilized in either a civil or criminal trial. Most often, they assist in criminal cases where there is a need to “understand the awareness, attention, and disruption, learning and recollection, fatigue, and hazard perceptions of one or more individuals.” Through their knowledge and insight, both the defense and prosecution may be able to better understand the motives behind the crimes and injuries at issue. Therefore, when there are many pieces of evidence, some of which may be contradictory, at play, a human factors expert witness can offer opinions about the elements involved and clear up any discrepancies. Human factors investigations may include, but are not limited to:

  • Attention and distraction
  • Conspicuity
  • Driver behavior
  • Expectancy and guidance
  • Human error
  • Memory and knowledge
  • Risk perception
  • Training Instructions
  • Vision and hearing

It’s important to note that the process behind these investigations may differ. However, most experts will start by reviewing all the evidence, testimony, or other connected items in the case. They may be able to determine if someone is involved in the criminal matter, if their behavior is indicative of guilt or innocence, or come to conclusions on similar issues based on observation or examination. Further, human factors expert witnesses will employ scientific methods and procedures when necessary to ascertain the location of the criminal matter, the time it occurred, or other similar issues within a case.


 Because the scope of science behind human factors expert is quite broad, the qualifications or backgrounds each expert has may vary. Many human factor expert witnesses have a background in psychology, human behavior, forensic science, engineering, or sociology.  Experts may have experience in other fields that deal with human behavior in the context of the environment, equipment, or other people. One human factors expert may possess different qualities than another expert in the field, so it is imperative that the specific elements of a case be determined and prioritized when searching and retaining a human factors expert witness.

Tallahassee Criminal Defense Attorney

If you or a loved one has been accused of a crime, contact a qualified Tallahassee criminal defense attorney who will exhaust all measures, including finding an expert witness to assist in your case. Don Pumphrey and the members of the legal team at Pumphrey Law Firm have experience dealing with all kinds of criminal charges and will consult with knowledgeable expert witnesses in the field, such as the field of human factors, so every applicable defense is explored. Call us today at (850) 681 – 7777 or send an online message today to discuss your legal matter during an open and free consultation with an attorney in our legal team.

Written by Sarah Kamide

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