Reasonableness and Reaction Time in Police Use of Force Incidents

by | June 17, 2019

Editor’s note: This article builds on concepts introduced in Chief Ranalli’s previous article on the limitations of video evidence in police use of force investigations. This article originally appeared in The Chief’s Chronicle; New York State Association of Chiefs of Police. Reprinted with permission.

In my last article, I modified the facts of a 2018 decision of the United States Supreme Court, Kisela v. Hughes (138 S.Ct. 1148 (2018)), to include the impact of video. For purposes of this article, I will revisit the Kisela case and stick to the facts cited within it.

Kisela v. Hughes

Officers responded to a call of a woman, Amy Hughes, acting erratically and hacking at a tree with a knife. Upon arrival, officers saw Sharon Chadwick standing next to a car in a driveway. Hughes then came out of the house carrying a large kitchen knife down at her side, with the blade facing to the rear, and walked toward Chadwick. Hughes stopped no more than six feet from Chadwick. The officers had their guns out and were separated from the women by a chain-link fence. They commanded Hughes at least two times to drop the knife, but she kept it in her hand. Believing Hughes to be a threat to Chadwick, Officer Kisela fired at Hughes four times. The entire incident took about a minute.

Hughes survived her injuries and sued the department and the officers. The majority of the Supreme Court did not rule on whether Kisela violated Hughes’ Fourth Amendment rights. Instead they ruled Kisela should have been granted qualified immunity since, under all these circumstances, Kisela’s actions did not violate any clearly established law. Hughes was behaving erratically, possessed a large kitchen knife, moved within just a few feet of Chadwick, and refused commands to drop the knife. Kisela had to quickly assess the potential threat to Chadwick based on the available information known to him at that time.

Two judges issued a strong dissent, ruling that a jury could find Kisela violated Hughes’ Fourth Amendment rights. They relied heavily on the fact that only one of three officers fired, while the other two subsequently stated they felt they still had time to attempt verbal techniques. The dissenting judges also pointed out Hughes made no aggressive or threatening movements, nor did she even raise the knife; she was just close to Chadwick, holding a knife she would not drop. Not surprisingly, media accounts of the decision accentuated the opinions expressed in the dissent.

If a person is posing a potential threat to someone with a knife or other type of weapon, and ignores commands to drop the weapon, at what point do the rights of the person at risk rise to a greater priority than the person causing the risk?

Again, the Supreme Court did not rule that the shooting of Hughes was justified under the Fourth Amendment, instead limiting its ruling to the question of qualified immunity. The Court granted qualified immunity to Officer Kisela because there was no clearly established law that would cause a reasonable officer to know that deadly force under these circumstances would constitute a violation. Similarly, this article isn’t meant to suggest that shooting a person under similar circumstances would always be justified or the best course of action.

Without being there it would be impossible to definitively state that Officer Kisela’s perceptions justified the use of deadly force one way or another. Since Hughes’s actual intent never manifested itself, whether she would have attacked Chadwick will never be known. As discussed in my previous article, the fact that the attack never took place creates a bias against the officer for not knowing the intent of the suspect at the time. Reasonableness requires, however, consideration of whether the suspect was in fact intent on stabbing the victim. If that was the case, then Officer Kisela probably could not have stopped it without use of deadly force.

What is learned after the shooting should be irrelevant to determining whether the officers’ actions were reasonable, but too often this knowledge becomes a factor in how officer-involved shootings are perceived by the media and the public. Police leaders need to be familiar with the concepts of reasonableness and reaction time in police use of force when interacting with the media and the public.

21-Foot Principle Clarified by Dennis Tueller and Ken Wallentine

The Speed of Life: Action Versus Reaction

A person can act faster than another person can react.(1) The typical training example given is that a person who has a gun in their hand at their side will be able to shoot it before an officer with a gun, already pointing at the suspect, can fire in response. The time it takes an officer to respond to a threat, also known as the perception-reaction time, can be summed up as follows:

Mental Sequence (reaction time) + Physical Sequence (movement time) = Response Time

Reaction time is further broken down into essentially three components:

  1. Stimulus identification (see what is happening)
  2. Response selection (interpret what is happening and choose)
  3. Response programming (send signal to body to react)

The officer, reacting to the action of the suspect, is at a tremendous disadvantage since he or she must move through all three components. The suspect does not, since they have already assessed the situation and decided on an action, all without the officer’s knowledge. All the suspect must do is complete the physical action of firing his weapon. In the Kisela case, this would mean closing the remaining distance and stabbing the victim.

This is the reality of human performance and response. Reactions to changes in stimuli do not occur instantaneously.

In a complex environment such as our scenario, the officer’s response time can range from .7 to 1.5 seconds.(2) During that time the suspect may be moving. In the time it takes the officer to complete the response (from identification of the stimulus to the physical sequence), the suspect may end up in a completely different location or facing a different direction. Then we must add more time for the same process to occur in reverse—meaning it will also take time for the officer to perceive the movement of the person and respond. This process is why some suspects are shot in the back. In such cases, when the officer started the process of firing his or her weapon, the suspect was facing them, but in the time it took to fully respond, the suspect had turned. Officer Kisela fired four rounds at Hughes. Was it possible that one round may have been enough to render her incapacitated? It is possible, but by the time Kisela would have perceived this he could have easily fired the remaining rounds.

This is the reality of human performance and response. Reactions to changes in stimuli do not occur instantaneously. Consider a couple simple examples: You are ending a phone call and are reaching for the end button when the other caller says, “Oh, one more thing” but your finger hits the button, ending the call. You heard it, it registered in your brain at some level, but your brain could not catch up to the motor program already being executed to stop it. Another example is a basketball player going up on a layup, but the ball is rejected by a defender. The shooter’s hands still complete the motion of the shot, even though the ball is no longer in his or her hands. It takes time to register the change in stimuli and generate a response.

Implications for Law Enforcement

The implications of these concepts place officers in potentially unwinnable situations. Where is the priority of life in such situations? If the officer had waited, and Hughes had attacked Chadwick, she could have closed the short distance and stabbed Chadwick before Kisela could have effectively reacted. The angle and positioning of the people involved could also then be an issue, with the victim at risk of being unintentionally shot as well. Obviously with excessive force cases the focus is on the rights of the person bringing the lawsuit. But we must also ask, what about the rights of innocent persons?

If a person is posing a potential threat to someone with a knife or other type of weapon, and ignores commands to drop the weapon, at what point do the rights of the person at risk rise to a greater priority than the person causing the risk? This is what objective reasonableness is all about (and why the standard should not be changed).

In a domestic case in a jurisdiction near mine, a man held a knife to the chest of his partner and was increasing the pressure as he told officers to leave. Attempts at communicating with him failed and he ignored all commands to drop the knife. One officer was able to get into a position where he could fire his weapon without risk to the victim. He did so and the victim was safe and relatively uninjured, but the suspect died from his wounds. In my subsequent conversation with the district attorney regarding the case, I indicated that the right of the victim to live overcame the criminal actions of the suspect. It was the suspect creating the risk, not the victim. Waiting for a clear signal that the suspect would stab the victim is untenable. Audio from the in-car camera system revealed the officers had given more-than-sufficient warnings, which were ignored by the suspect. In fact, my initial reaction was they had waited longer than necessary as they clearly did not want to shoot the suspect.

While justification in this case is obviously clearer than the facts of the Kisela case, the principle remains the same. Officers must assess risk in situations where whatever choice they make can lead to a tragedy. Therefore, it is important for officers to understand the priority of life and, if necessary, the risk must fall back on the person who is creating it.

In my last article I concluded with a list of considerations for police leaders to use when preparing to explain a use of force incident. The concepts of reasonableness and reaction time in police use of force should also be included in that list.


  1. See generally: Blair J, Pollock J, Montague D. et al. Reasonableness and Reaction Time. Police Quarterly, 2011;14(4):323–343; Lewinski W. and Hudson B. Reaction Times in Lethal Force Encounters: Time to Start Shooting? Time to Stop Shooting? The Tempe Study. Police Marksman. 2003;28(May):26–29; Schmidt RA and Lee T. Motor Control and Learning: A Behavioral Emphasis (5th ed.). Human Kinetics: Champaign, Ill., 2011
  2. See the Lewinski study mentioned above, as well as Lewinski W and Hudson B. The Impact of Visual Complexity, Decision Making and Anticipation: The Tempe Study Experiments 3 & 5. Police Marksman. 2003;28(Nov/Dec):24–27.

MIKE RANALLI, ESQ., is a Program Manager II for Lexipol. He retired in 2016 after 10 years as chief of the Glenville (N.Y.) Police Department. He began his career in 1984 with the Colonie (N.Y.) Police Department and held the ranks of patrol officer, sergeant, detective sergeant and lieutenant. Mike is also an attorney and is a frequent presenter on various legal issues including search and seizure, use of force, legal aspects of interrogations and confessions, wrongful convictions, and civil liability. He is a consultant and instructor on police legal issues to the New York State Division of Criminal Justice Services, and has taught officers around New York State for the last 15 years in that capacity. Mike is also a past president of the New York State Association of Chiefs of Police, a member of the IACP Professional Standards, Image & Ethics Committee, and the former Chairman of the New York State Police Law Enforcement Accreditation Council. He is a graduate of the 2009 F.B.I.-Mid-Atlantic Law Enforcement Executive Development Seminar and is a Certified Force Science Analyst.

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