Editor’s Note: Knowing how hard an officer hit somebody with a baton and for how long can be critical questions in a use of force case. Join Dr. Geoffrey Desmoulin, a Certified Force Science Analyst and Principal of GTD Scientific Inc., as he describes how Force Science studies and GTD tactical baton research were applied to successfully answer these questions in a controversial police use of force.
Setting the Stage
In response to a domestic violence call, officers met with the victim at her residence. The suspect had reportedly left the area but soon returned. After a knock at the door, the officers greeted the suspect and, with their body-worn cameras engaged, instructed him to stay in the building’s hallway. The suspect immediately became verbally abusive, failed to follow instructions, and began to fight with the police.
One officer used his expandable baton in an attempt to subdue the suspect. Video from the body-worn camera shows an officer striking the suspect eight times. While the limbs were assumed to be the primary targets during the confrontation, the third strike contacted the back of the suspect’s head. Following the sixth strike, the suspect said he would comply and appeared to stop fighting. He was subsequently restrained by the officers and provided medical aid.
In the months following the incident, the suspect complained of incident-related medical complications and sought to sue the officer and his department. At that point, GTD Scientific Inc. was retained to examine the body-worn camera footage and apply injury biomechanics methodologies to help explain the magnitude and duration of the officer’s use of force.
Physics and Injuries
As is often the case, a biomechanical explanation of reported injuries is a critical component of use of force investigations. By identifying the magnitude of force necessary to create injuries generally, we can start to identify and explain the cause of specific case-related injuries.
In this case, multiple cuts and bruises were identified on the suspect’s body. From the video we identified two cuts; one on the back of the head from the third strike and one on the shin from the fourth strike. In addition to the cuts on his shin and head, bruises were located on the suspect’s arms and leg.
Using previously published research, including that from GTD Scientific Inc., we estimated the magnitude of force needed for a baton to create the injuries seen on the video.1 2 3 The injuries then allowed us to identify the range of force involved with each baton strike delivered by the officer.
GTD-NYPD Baton Testing
Among the research which helped identify the range of force used in this case was our own GTD Scientific Inc.’s independent baton testing data and experience. Working with active duty officers from the New York Police Department (NYPD) a few years prior, we identified the range of forces that an average officer could generate with batons of different sizes, including a baton like that used in this incident.4
From these previous studies, we could identify how the magnitude of force (load) generated by a baton affects the body. In other words, we identified the type of injuries we would expect to see when compared to how hard an officer hit someone with a baton. We then looked at the injuries in our specific case and identified the magnitude of force as a percentage of peak load. This percentage would give us an estimate of how hard an officer hit the suspect in relation to how hard he could have hit the suspect at “full force.”
The baton data shown in the graph above shows the force generated by officers using maximum effort. From the data we compared the range of strike efforts to known injury tolerances. Since the head strike did not result in a skull fracture, it was determined with reasonable certainty that the officer never struck the suspect with more than 40% of maximal effort in his intervention.
Continued Beyond “Compliance”
The magnitude of the use of force was not the only question posed in this case. We were also asked to look at the duration of the force. Specifically, we needed to explain why the officer might continue to strike the suspect even after the suspect could be heard giving up. To answer this question, we looked to Force Science research and considered their time to stop studies.5
In our case, while the suspect was struggling with an officer, other officers can be heard instructing the suspect to “get down on the ground.” Although the suspect did not initially comply, he eventually announced his submission, after which the officer delivering baton strikes stopped and the suspect was subdued.
The duration of force was questioned after a careful review of the video showed that the officer delivered two additional strikes after the suspect exclaimed his submission. Given the dynamic nature of the incident, it is unclear whether the officer heard the suspect or interpreted his words as a definitive sign of submission.
The lack of clarity in use of force encounters highlights one of the greatest challenges in measuring and assessing an officer’s response to dissipating threats. Dr. Bill Lewinski, the executive director of the Force Science Research Center, has explained, “An officer perceives what they pay attention to, and in use of force encounters there can be a lot of equally important stimulus competing for their attention. In this chaos, officers must first perceive and recognize that the suspect has ceased to be a threat before the officer will change their response to the threat.”
“An officer perceives what they pay attention to, and in use of force encounters there can be a lot of equally important stimulus competing for their attention. In this chaos, officers must first perceive and recognize that the suspect has ceased to be a threat before the officer will change their response to the threat.”Dr. Bill Lewinski
Without knowing exactly when the officer perceived the suspect’s submission, we chose to identify the suspect’s vocal submission as the earliest objective stimulus, which could have theoretically prompted the officer to change his response. This allowed us to presume the most conservative time estimate and give the greatest benefit to the suspect.
Using the suspect’s verbal submission as the “change stimulus,” we identified the timing of each baton strike in relation to this change and other observable events. As illustrated in Figure 2, the officer delivered a total of two strikes after the suspect showed the first possible sign of submission. These two strikes occurred within 1 and 1.5 seconds of the “change in threat level.”
We compared our findings to independent Force Science research, which detailed the factors that affect an officer’s speed of response when they detect a change in threatening behavior. After considering theoretical research, applied research, and clinical research, Force Science observed that, in dynamic, “real-world” encounters, the total amount of time for an average officer to respond to a “change in threat” was as high as 1 to 1.5 seconds.
Even using the earliest possible change stimulus for our analysis (the suspect’s verbal submission), the officer in our case stopped his baton strikes within 1.5 seconds of the “change in threat level.” This finding was consistent with time it can take an officer to stop the use of force in response to a perceived change in threatening behavior.
Drawing Conclusions from Video
Asking how hard an officer struck somebody with a baton or wanting to know why they didn’t stop immediately are reasonable questions in any use of force case. In our case, we were able to use video from the body-worn cameras to capture two quantifiable metrics. First, strike magnitude studies compared with observable injuries allowed us to show that the force employed by the officer was submaximal—he didn’t hit the suspect as hard as he could. This evidence strongly supported the position that the officer wanted to control the subject rather than harm him.
Second, time measurements considered in light of response studies, allowed us to show that the time the officer took to react to the earliest possible indication of surrender, fell within the range expected during dynamic use of force encounters.
As a final note, the findings in this case were made without direct measurements from the scene. Instead, the key to understanding the magnitude and duration of force was the timely use of the officer’s body-worn camera.
- Lee, R.H., Gamble, W.B., Mayer, M.H. and Manson, P.N., 1997. Patterns of facial laceration from blunt trauma. Plastic and reconstructive surgery, 99(6), pp.1544-1554. [↩]
- Allsop, D.L., Perl, T.R. and Warner, C.Y., 1991. Force/deflection and fracture characteristics of the temporo-parietal region of the human head. SAE transactions, pp.2009-2018. [↩]
- Desmoulin, G.T. and Anderson, G.S., 2011. Method to investigate contusion mechanics in living humans. Journal of forensic biomechanics, 2. [↩]
- MacIntosh, A. R., & Desmoulin, G. T. (2019). Police Officer performance and perception using light, medium and heavy weight tactical batons. Applied Ergonomics, 75, 178-183. [↩]
- Lewinski, W.J. and Redmann, C., 2009. New developments in understanding the behavioral science factors in the “stop shooting” response. In Law Enforcement Executive Forum (Vol. 9, No. 4, pp. 35-54). [↩]
Very interesting discussion, and some very valid points.
Although explaining that the time to perceive and stop striking the suspect is desirable, there are real errors in logic here. First, how hard the officer hit often has no relation to his intent. Second, we teach officers to hit as hard as they can to stop the encounter. Teaching officers to hit with limited impact puts them at risk. When the suspect realizes that the officer’s blows are not that bad, it gives them the freedom to continue the attack. So, now the officer is forced to shoot or the officer is injured or loses their gun in the fight. There are many variables in how hard a suspect is hit. Quantifying those is not a good idea. Next, people will expect the officer to gauge just the right amount of power in a rapidly moving environment against an opponent who may take some unknown level of force to subdue. They will want you to hit with just the right amount of force. This will be comparable to shooting the gun out of his hand. If someone is hit in the head, that should only be by accident in a rapidly moving event unless deadly force is justified. Force Institute’s studies should go a long way toward showing how the suspects position could change in the time it took for the officer to swing.
Don Black, I completely agree (you beat me to it). Graham v. Connor (1989) instructs us not to consider an officer’s intent when responding with force but to weigh only the objective criteria known to the officer at the time. When an officer reasonably resorts to a baton, it is generally the only available option short of deadly force. Scott v. Harris (2007) instructs us to consider the likelihood of injury to the suspect by the officer’s actions when weighed against the reasonably perceived threat of the suspect to others (including the officer). A baton is intended to create both great pain and some degree of injury to suspect. Impact weapons create compliance through pain avoidance and/or stop suspect threat by disabling the suspect by striking a limb and rendering it less effective or even ineffective (this may be either through great pain, e.g., hitting a bony surface, or through fracture).
A generation of officers have been trained in the “Green, Yellow, Red Chart” targets. The development of this targeting scheme was solely for product liability purposes as well as industry acceptance (gaining sales) of new products, not for LE civil liability or officer safety. This targeting scheme is based on experimentation: hitting the green targets is wholly ineffective by design, so after several strikes where the suspect becomes emboldened and if the officer is not rendered incapable by the suspect, yellow targets that can be expected to effectively dissuade or disable the violent suspect are then attempted. Multiple strikes to ineffective targets and/or being trained to modulate baton strike intensity (lighter for some strikes and heavy for others) creates liability for the officer and agency rather than reducing it because multiple baton strikes–and resulting bruising, lacerations, or fractures–appear to be excessive.
Because of the likelihood of injury when employing a baton, officers should be trained and endeavor to strike a violent suspect with full power to effective targets (bony surfaces) in order to: 1) quickly stop the threatening suspect through compliance; 2) quickly stop the violent suspect through creating disability, and/or; 3) limit the appearance of extended brutality by limiting the number of strikes needed in this instance.
So much of FS’s research is extremely valuable for society because it explains why humans in uniform immersed in high-threat situations respond as they do. That said, research must support the reality faced by officers as well as the laws governing their actions, not unnecessarily complicate it. It must be remembered the officer is being forced to resort to using a length of wood or metal to defend or control a suspect–it’s expected to cause injury. After all, this individual is so dangerous/threatening/out of control that the baton is last reasonable, effective option prior to deadly force. While the author’s research is fascinating, Don Black’s comments are spot on.
The reasonable answer to how hard the officer struck the suspect is, “As hard as possible to an apparently effective target in order to attempt to stop the threatening behavior of the suspect, yet the suspect continued to be a threat even after this/these strike(s).”
This has obviously struck a cord. However, there is some mis-understanding as to what we addressed. Since you seem to agree with Don please read my responses to Don and should you have any additional questions I’d be happy to address them.
I don’t understand how it is relevant how hard the officer hit the suspect with his baton. If you are justified in hitting someone with an impact weapon, you are justified in hitting them as hard as you can. Tactically, this is preferred (and should be taught) because you are more likely to overcome resistance and end the threat if you hit as hard as you can. By not hitting as hard as you can you are possibly, and probably, causing the event to continue, resulting in a longer use of force. Which looks worse, 1 or 2 good hard hits or 7 or 8 hits? Are you saying this wouldn’t have been justified if the officer used 100% of their strength? If so, where is the cutoff? If that’s not what you’re saying, then why spend the resources to figure it out? Maybe I’m just missing something, but this seems like something we wouldn’t want to spend resources on to figure out, and we shouldn’t be rendering opinions that the fact the officer used only 40% of their strength was a “good thing”.
Thank you for your comments on here. Please see my responses to Mr. Don Black and should you have any more questions I’d be happy to address them.
My comments are directed toward Mr. Black above:
A) First and foremost: There is always value in quantifying anything as it simply gives you more information about an event than you had previously and, in my opinion, much more information. To say otherwise is against the goal of science. This is why Force Science research has been so critical to defending officers. They found that measurements helped describe deadly force encounters more accurately. We are doing the same through the lens of the engineer and kinesiologist. How you break that information down however and what it actually means is open to interpretation and that is where I believe you are taking issue. I also don’t assume that these are your only thoughts on the matter so I’d appreciate it if you assume the same from me. In any-case I will attempt to address your concerns below.
B) To your first point. You assume that we did not discuss or address the difference between intent and strike force/effectiveness. You are partially correct in your interpretation here but without quantifying what you actually mean by “how hard the officer hit often has no relation to his intent” you cannot say that with any amount of certainty (see A). My answer here would be that “it depends”. But of course that is obvious. Since, a 100% effort swing that misses its intended target will not impart any load. So you must consider conditions of impact in order to make your statement, dare I say, quantifiable. Impact angle, target shape, relative friction, target stiffness, linear vs. angular velocity fo impact, impact location of baton, the list is much longer but for brevity I’ll stop here. Our full length study on the subject is on our website and I urge you to read it since it shows (not my guess work) that officers do hit much differently during dynamic situations vs ideal conditions. Some of the above are addressed, quantifiably.
3) To your second point. Please do not put words in my mouth and I will return the favour. No one crawled inside the officer’s head and measured what the intent actually was at the time of the incident. What we said was based on past research and the injuries imparted by the strikes the officer during the incident investigation by us, he could have hit much harder. This is a fact of independent information whether you or anyone else likes it or not. This is the beauty of quantification and I urge you to base your teaching on quantified information although I understand there is a paucity of information in this area. Further, no one said to hit with variable intent, as I understand it officers are taught to vary force proportional to the threat. A baton could be a variable force option by changing target not neccesarily varying force of impact. Make sense?
C) I wholly and passionately disagree with your statement: “There are many variables in how hard a suspect is hit. Quantifying those is not a good idea.” This is analogous to saying: “There are many variables in building a bridge. Quantifying those is not a good idea.” Again, anyone, whether they like it or not could agree that quantifying bridge building is probably a good idea and therefore the first statement is not only ill advised but quite simply a dangerous proposition.
D) You make many assumptions around the unfolding of events discussed on this topic and how people may perceive them. I choose not to address any of them, at least at the moment, as I find them pure conjecture and a tad amplified but I could be wrong.
E) Your research idea on how much a person can move from the time the officer starts the swing to the time they make contact is a good one. It in fact your statement here shows that you support my idea on quantifying the issue. We would have most certainly used this data had it existed when we were asked to investigate. The thought was certainly discussed in our report however. Let’s work together on this and many other questions we have in common!!
F) Thank you for your post and I’m glad it conjured discussion as it is only when our fields and others collaborate on these issues will we ever get to the truth. Communicating that truth to the courts and the lay in general will be the next massive task. We (GTD) have been stuck there for quite some time.
All the B=best,
While I agree that a strike with a baton tried should be done accidentally or in a deadly force situation. The determination of how much force the officer uses with the baton is important in any civil case. It is true that we teach officers to strike as hard as they can however when a plaintiff makes an allegation that he was hit very hard in certain areas this type of study from Force science could be very valuable to defend the officer.
…and it was. Thank you for recognizing that.
Has any of your quantifying research taken into consideration the amount of injury, such as bruising, may occur in an individual that takes an anticoagulant or antiplatelet medication?
Great comment. The numbers we use are of course averages as contusions are obviously highly specific to the person the bruise occurred in. Medicine is only one of many factors that can affect bruise severity and likelihood. However, on average as load increases the likelihood of contusion increases but so do the probabilities of other more severe injuries. So you need to think about this as a spectrum, not a threshold although threshold is often cited as it is much easier to understand. Further, the methodology we present in our data paper on bruising in humans could be used to understand bruising threshold and patterns in the person of interest. Refer to the paper for details. It can be found on our website: http://www.gtdscientific.com.
Thank you for responding. Although I support the scientific efforts by GTD and Force Science, I believe that there is a problem in your interpretation of the meaning of your findings. Force Science studies in reaction time have validated what some trainers have been teaching for over 50 years. The failure by law enforcement to understand reaction time has resulted in numerous officer deaths. A simple example would be an officer standing in front of a suspect and telling him to take his hands out of his pockets. Recent videos of officers being shot have caused groups (like Calibre Press) to finally reevaluate that tactic. Most agencies teach officers to handcuff before searching. This ignores the reaction time involved and is getting many officers killed.
Since I have had long experience in baton techniques, I would be curious as to what NYPD considers a baton strike. Further, experience on the street has shown me that science doesn’t translate directly. There is a reason that some buildings and bridges fall down (designed by engineers). I have seen many human demonstrations of strength, endurance, and durability that would defy scientific explanation.
Although the science makes good sense, I find that the interpretation of its relevancy is often skewed by people who are not familiar with street police work. I have seen many cases where the science has explained reactions but ignored the fact that an experienced officer is often not subject to those same limitations. Unfortunately, this makes excuses for officers who should not be excused.
The real problem is how the attorneys will apply your findings. In defending an officer, there should not be an issue of how hard he hit with he baton. He has to hit as hard as he can to end the assault. He can’t be concerned with it while in the act. There are, of course, some exceptions where the individual is obviously less capable of attack. There is a world of difference between the scientific issue and the legal issue. The officer must be legally justified in using that level of force. When a baton is used, injury is expected. The severity should be modulated by the target area selected. In a moving environment, other areas may be struck accidentally. If one does not expect injury, one is being naive.
We can agree to disagree. For the most part, I believe that scientific research is benefitting law enforcement by explaining the physical factors involved. For that, we would have to commend the efforts of Force Science and GTD.
Don, now we are having a conversation.
NYPD is ASP Inc. trained. As I am an ASP Inc. certified instructor I know that there are zero requests to gauge strength of strike to that of force, only targets.
RE: Bridges falling down. Yep, it happens. People make mistakes, materials are manufactured incorrectly, the list goes on… but imagine the issues we would have if we didn’t have our quantitative approach and government regulated professions.
Agreed, science attempts to isolate an output in order to understand how it changes under various conditions. Doing this by its vary nature changes the environment in which the test takes place making it less realistic. In the baton study I tried several tiers of tests, from more static and isolated to more dynamic so that we could get a range of information and try to understand how trends changed in the various conditions so as to identify the more important factors. It is critically important the scientists work with officers in order to understand the environment in which they work and assist to create the important questions to ask scientific to answer.
Again, I never said that the officer should change their response of strike only that the officer involved could have hit harder according to the numbers. Why is a complicated answer that the article did not address. So, please stop.
As for attorney’s screwing the information I can only suggest that police defence attorney’s hire the right team with the right expertise and let them do their jobs. We do not do Police operations. I addressed the rest of your paragraph previously.
Agreed on the last paragraph but I believe we agree more than disagree.
Interesting. As a former serving Police Officer of 18 years, involved in multiple force on force incidents, riots and an Instructor in Defensive Tactics I have encountered subjects who have shown no response to multiple baton strikes using maximum effort for each and every strike. No one has mentioned here (unless I missed it) variable factors such as mental disability and or drug induced disability. You simply cannot measure how hard you should strike the subject. The intent is to incapacitate the subject from continuing to be a threat as perceived by the Officer. If that takes, 1 or 6 strikes so be it. It is not the intent to harm/hurt or cause injury to the subject. That is a consequence of the subjects unlawful actions. Then as a Police Instructor and now as an Instructor in the Private Security Industry, I instruct my students to “hit as hard as they can”, because how hard is hard enough !!!
Simon. Thank you for your comments. For some reason some people are mis-understanding the article. I only said the officer could have hit harder, which is fact. Plain and simple, it is unarguable and a non-issue.. I did not comment on whether or not he should have regulated the strike based on threat level which is what some people are mis-understanding. As a certified ASP Inc. baton instructor and baton researcher threat regulation with a baton is typically done through choice of target. Further, we did not comment on whether the choice of target was appropriate or not. Anyway, I’m glad this is churning up some emotion and cause for comments.
Pretty much what Don said (i.e. I agree with him).
To add a couple of pesos off the top of my head:
In addition to every strike from the first one being as hard as possible, I also teach to target bone if/when possible (which is contrary to what I’ve seen taught in the vast majority of all the LE impact weapons/baton training, even instructor courses, that I’ve been through). In FMA, “wood seeks bone, steel seeks flesh”. If you want to be kindler/gentler, there are other non-striking techniques that can be done with batons.
A lack of significant or serious injury does NOT automatically equal a lack of (or less than maximum) effort/force – and vice versa. Injuries are a case by case basis – not every person bruises the same, not every person breaks as easy/hard, and not every part of the skull fractures the same or as easily either, etc.
Force applied via a baton is also a case by case basis – in addition to what Don said about a multitude of factors influencing how much impact force someone can generate with a baton strike, if you’re actually measuring, you need to measure the actual user of the baton using his/her baton – and Not use data collected from other people using a similar baton.
I think the concern from the officers reading the article is that the information you are quantifying and the way you are using it can be used as a double edge sword. If you want someone to draw the same conclusion as your article did “This evidence strongly supported the position that the officer wanted to control the subject rather than harm him.” then the opposite can be said for the next officer when the analysis shows that officer used full force. You will have someone saying that officer intended to cause harm or injury rather than gain compliance. In our line of work officers are careful not to try and make an argument out of something that can just as easily be used against us.
I found the information interesting from a analysis standpoint but it’s not something I would recommend officers using to justify their actions in a court of law, at least not the way it was presented in this article.
How hard you hit IS important. I know of a case which started very similarly to this one,. Due to a tactical error, an officer had to fight a suspect alone for a time before his cover got up the stairs to assist. The officer at one point intentionally struck the suspect in the head with his flashlight, but intentionally with a very short, light strike intended to distract and get a reaction from him rather than bash his head in. The use of force resulted in a small cut requiring a few stitches.
Of course, great concerned followed that this was a “lethal” use of force, because the targeting was the head. NO consideration was taken as to amount of force actually used. The amount of damage was used to defend that the officer intentionally DID NOT use much force, let alone a lethal amount, to produce the desired result. The idea at hand was what was reasonable under the law.
Looking at it simply as a “head strike” and considering that excessive was not reasonable. Assessing how hard the hit was helped to establish its reasonableness for that particular situation.
I thought the value of this research was its ability to answer whether it was reasonable for a jury to view the head strike as intentional, malicious, or deadly force. GTD provided critical evidence that can refute a plaintiff’s claim that an officer was out of control and intent on maiming a suspect or recklessly engaged in conduct that could kill a suspect.
I suspect most use of force instructors have been asked whether hitting someone in the head with a baton is deadly force. Like all good legal answers…it depends. How hard did you hit them? GTD’s research gives us a starting point to answer that question or to test an officer’s answer to that question by comparing statements to physical evidence.
Use of force instructors know that batons can be used to simply push suspects back, block, apply mechanical manipulations, and strike at increasing magnitudes. The police profession has moved away from force continuums in part because we know that empty hands can be lethal and impact weapons can be used at very low “levels” of force (push). Most continuums don’t distinguish between a 10% strike and a 100% strike by impact weapons and yet we would certainly argue they should be assessed differently. When instructors train officers to hit as hard as they can every time, I suspect they have a very specific “active assaultive” suspect in mind. They are imagining the need for neuromuscular disruption vs. pain compliance. I didn’t see GTD’s case assessment as calling into question the need to hit suspects as hard as you can when it is reasonable to hit them as hard as you can.
The Jury instruction in my circuit requires jurors to consider the “type and amount” of force used. Seems like knowing how hard the officer struck a person vs. how hard they could have struck them would be beneficial.
Geoff, excellent scientific work! Here’s the reason the hair on the back of my head goes up when I read that portion of your article:
Your statement: “First, strike magnitude studies compared with observable injuries allowed us to show that the force employed by the officer was submaximal—he didn’t hit the suspect as hard as he could.”
Your study made this logical conclusion simple and undeniable. There are no worries rising here.
Your statement: “This evidence strongly supported the position that the officer wanted to control the subject rather than harm him.”
Ooooooo…..yikes. If this statement is true, then the rules of human logic dictate that the reverse must also be true: If the evidence shows that an officer struck a subject as hard as he can, therein lies strong support for the position that the officer wanted to harm the subject rather than control him.
This is why cops, who might be called on to swing the baton tomorrow, are worried. Clarify for us why it is not likely the reverse-logic argument can be applied to tomorrow’s situation, and we will all sleep a little easier.
Hello Dave, Thank you for your comments here. Agreed, that the section of the article/report that is making your hair stand up should probably be reframed. All I’m saying is that: A) more information is better; and B) the load at impact was not what the officer was capable of, period. This does not infer that we climb inside of the officer’s head and reason that he was attempting to strike at less than maximal effort in order to control a subject, only that they did not strike with maximal effort. Now, this begs the question, why? I would guess any number of reasons but I would guess this is primarily due to a squirming subject and having a narrow hallway in order to induce the strikes. Hopefully, this sheds some light on how we are thinking about this and we will be more careful about how we frame the data in the future. Al the best and stay safe!