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Some law enforcement uses of force are associated with a term known as a "mistake of fact (MOF)." The MOF may occur when a law enforcement officer misunderstands some fact or misidentifies an object. A MOF may include an unarmed subject, a toy/replica weapon, or other known, but relatively, harmless objects (cellular telephone, wallet, television remote control, etc.). While a MOF use force can occur under any lighting conditions, at least 71% of all MOF police shootings occur at night (Aveni, 2002).

Scotopic vision is eye sight under low light conditions, with colors typically perceived only in black and white (Encyclopedia Britannica, 2006). Mesopic vision occurs in intermediate lighting conditions as a combination of scotopic and photopic (well-lit) vision. In most night-time urban environments, available ambient light allows the eye to use mesopic vision. Such vision provides poor acuity and no color vision (Green, M., 2013).

In their study of human vision in low light, Barton and Brewer found that the brain did not process information gained under low light any differently than in the light at noon day. The authors reminded, “We are functionally blind in the center of our vision under low light. . .” In an effort to compensate, human beings typically look at objects under low light at an angle to provide as much information as possible so that the brain can make decisions based on experience (Barton, B., Brewer, A., 2015). The authors continued, “What your brain is trying to do is guess what the sensation means and what’s causing the sensations so it can figure out what to do about them. Your brain is trying to put together thoughts, feelings, and perceptions so they arrive as needed, not a second afterwards.”

Thomas Aveni, of the Police Policy Studies Council, studied and tested law enforcement MOF uses of force in low light environments (2008). Aveni observed that a subject, “[With] a clenched hand exudes ambiguity. It is much less likely to be viewed innocuously, especially in the context of possible criminal activity.” In addition, Aveni found that more than 70% of the tested officers said their use of force decision was influenced by a subject turning toward them with “something” in their hand. “Noncompliance with verbal commands,” Aveni added, “was one of the most consistent factors” cited as a precursor to a shooting decision. “From that frame of reference, potentially aggressive actions made subsequently by a suspect would understandably be perceived as threatening.”

Aveni suggested that a “practical and altogether reasonable interpretation” of what an officer might do when, for example, confronted by a non-compliant robbery suspect, would be to preemptively shoot as the suspect initiates a turning motion toward the officer. Aveni concluded, “This will likely be construed as ‘controversial’ in some quarters, but this study’s findings certainly suggest that such latitude is both reasonable and necessary for an officer’s protection."

To what extent a law enforcement officer “can accurately discriminate a handgun from a cell phone, flashlight, or wallet held by a suspect at night is a source of concern. If a subject does the wrong things at the wrong time, a reasonable officer is likely to pull the trigger, believing his own life to be in peril (Police One)."


Is a trained law enforcement officer subject to the conditions of human physiology? Why, or why not?

Is a MOF a law-enforcement-only, or human condition? Why?

Generally, human eyesight is poor in low light conditions. How might this condition influence a law enforcement use of force? How should your answer be considered when examining a low light use of force for reasonableness?

How can an understanding of how MOF uses of force can occur assist with the objective, reasonable analysis of a similar use of force?

Does a MOF use of force negate an element of a criminal offense (crime)? Why, or why not? If so, which one?

Why do the majority of MOF shootings occur at night? Is this to be expected? Why, or why not?

How does the brain "see" in low light? Is this different, or the same, as what the eye sees? Could the brain's perception be different from a video recording of the incident? Why, or why not?

Is it reasonable to expect a law enforcement officer to perform outside human capability?


Aveni, T. (2008). "A Critical Analysis of Police Shootings Under Ambiguous Circumstances." The Police Policy Studies Council.

Barton, B., Brewer, A. (2015). "fMRI of the rod scotoma elucidates cortical rod pathways and implications for lesion measurements." Proceedings of the National Academy of Sciences Apr 2015, 112 (16) 5201-5206.

Encyclopedia Britannica, (2006). "Eye, human." Ultimate Reference Suite DVD.

Green, M., (2013). "Visual Expert Human Factors: Night Vision."…/1665473-What-the-new-study-of-…/

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