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Edged weapons: traditional and emerging threats to law enforcement.

The actions of the September 11, 2001, hijackers clearly demonstrated the genuine threat of an edged-weapon attack. They showed that someone with a relatively small amount of training and a crude cutting instrument could inflict serious bodily injury or death. Although attacks of this magnitude are relatively rare, law enforcement officers frequently encounter individuals with edged weapons. While the majority of these subjects may carry these weapons for defense against other street criminals, they, in fact, may use them against officers under the right circumstances.


By examining some of the issues involved with edged-weapon attacks, officers can garner a framework for future training and awareness. While some of the weapons officers now face are the same ones they encountered 30 years ago, a number of new products have reached the commercial marketplace that will require them to adapt to these emerging threats.


Almost all of the research on edged-weapon assaults has come from Great Britain where, due to their stringent gun laws, attacks most likely occur with an edged weapon, rather than a firearm. The majority of this research involved case studies that analyzed the type of attack (e.g., slash versus stab) from hospital admissions or autopsy reports from the medical examiner's office. While many of these studies occurred over a long period, the sample sizes were quite small. (1) Much of the other available data dealt with stab or slash protection, the physics of edged-weapon attacks, the types of edged weapons most commonly used in attacks, and the probability of survival. While all of this information exists separately, it would benefit law enforcement officers for it to be summarized and analyzed in its totality.

Case Studies

Of the six case studies that the authors found, five relied on information from sources in the United Kingdom and one came from Kuala Lumpur, Malaysia. Of the studies from the United Kingdom, four were from England and one from Scotland. Much of this literature has come from the United Kingdom because stabbing is the most common method of homicide in that area. (2)

In each of the studies, except for one, (3) the researchers recorded the location and number of wounds in addition to the age and sex of the victim and, when available, that of the assailant. For law enforcement officers, the most important information gleaned from the research revealed that in every study, the average number of stabs or slashes was one and that in many cases, that one strike was enough to cause the victim's death. Of course, all of these attacks involved victims not wearing body armor. This would make it much easier to thrust into the heart of such a person than into an officer wearing a stab-resistant protective vest.


Four researchers studied 120 victims admitted to an Edinburgh hospital for edged-weapon attacks. (4) Of those, 20 died from their injuries, with 16 of them experiencing the most severe trauma to their chests and only 5 making it to the hospital for treatment. Of 148 homicides from stabbing recorded by the Royal London Hospital, 67 had a single, fatal stab wound. (5) The researcher calculated that of these 67 single wounds, 22 hit the heart and 17 the heart and a lung. Multiple stab wounds accounted for the remaining 81 homicides, and, of these, deaths occurred from chest wounds in 61 cases. In another study, 36 percent of male assailants inflicted one wound compared with 57 percent of female offenders. (6) Of these single fatal wounds, 27 out of 39 hit the chest of the victim. Of an additional 74 lethal stabbings reviewed by researchers, 27 single wounds were fatal, with 18 of these occurring in the chest. (7)

Just as in the United Kingdom, edged-weapon attacks are a common method of homicide in Malaysia, but one researcher determined that slash or chop injuries produced more fatalities than stabbing wounds. (8) The study dealt with 37 cases from a 10-year period of autopsies at the University Hospital in Kuala Lumpur. Out of 27 cases that fit into the researcher's "intentional violence" group, 16 of the victims received more than 5 wounds from their attackers. Of all of the cases involving multiple wounds, 18 were directed at the head, 15 to the neck, and 12 to the trunk, or torso, of the victim. Only eight victims died as a result of a single wound and six of these involved neck wounds. These statistics coincide with the study's examination of slashes as it is much easier to produce fatal trauma by slashing at the neck (e.g., severing vertebrae or hitting the carotid arteries) than it would be to slash at the chest because the ribs provide a great deal of protection to the heart and lungs. Unlike the studies conducted in the United Kingdom that involved only knives, this study included swords, machetes, sickle-shaped implements, gardening tools, and various edged weapons indigenous to Indonesia, such as the curved karambit. Coincidentally, the karambit has seen a substantial increase in its use in the United States as several reputable knife companies have begun producing high-quality versions and a subculture of martial artists train with it.

Assault Data

A review of 20 years of law enforcement injury reports in the United States indicated that on average, 1, 358 officers are attacked with edged weapons each year. (9) This number has fluctuated over time, with its lowest point of 871 attacks in 1996 and the highest of 2,095 in 1992. On average, over the 20-year period, between three and four knife attacks on officers have occurred every day. This statistic alone illustrates the need for further edged-weapon awareness.


According to one researcher, the majority of civilian edged-weapon assaults occurred in the home and were inflicted with a kitchen knife, whereas a large number of injuries took place on the street with folding or sheath knives. (10) Recently, three British physicians called for a ban on large, pointed kitchen knives after finding that at least one-half of the stabbing cases involved this type of instrument. (11) Prior research has shown that the length of the blade is not as important as the sharpness of the tip when it comes to penetration of the skin. (12) Consequently, a blade with a length of less than 3 inches can produce a fatal stab injury, while an adequately sharp instrument of any length can inflict a fatal slash to a sensitive area, such as the neck. "The ideal weapon is, in fact, a short thin-bladed knife, with a stiff blade, about 7 cm in length--many lock knives and small sheath knives fall into this group. Larger knives (ornamental daggers, militaria) required far greater force." (13) Unfortunately, most state statutes' definition of a common pocket-knife, which is legal to carry without a permit, provides little legal recourse in the reduction of these weapons on the street. As a result, officers tend to overlook the potential threat to their safety.

In the past, officers making contact with an individual carrying a balisong (butterfly knife) automatically would view the person as a potential threat. They assumed that the subject could produce the weapon rapidly for immediate use. Recently, a number of knives that can be deployed much more rapidly than the balisong and, yet, are legal to carry in most jurisdictions have been marketed to the civilian population. The emergence of the one-handed opening knife presents a much greater threat as someone can draw it quickly from a pocket and open it in less than a second. Some manufacturers design their knives so they open as the person draws it. If suspects have knives clipped to their pockets, they are essentially "on guard" whenever their hand touches the clip. Yet, many officers often fail to recognize this as a threat and may allow a suspect to retain the weapon during an encounter.

Frequently, individuals carry one-handed opening knives in their front pants pockets on the strong side of their bodies. Officers can easily identify these weapons by a metal clip that extends 1 1/2 to 2 inches out of a suspect's pocket.


The 21-foot rule, a dogma of law enforcement training, has held that at a distance closer than 21 feet, a suspect with an edged weapon in hand could stab an officer before that officer could fire two shots. However, one researcher found that an individual can cross 30 feet in 2 seconds and suggested that the person could travel 70 yards before succumbing to injuries created by an officer's firearm. (14) According to the FBI, "There is sufficient oxygen within the brain to support full, voluntary action for 10 to 15 seconds after the heart has been destroyed." (15)

This suggests that 21 feet is an insufficient safety zone during an edged-weapon encounter. Unlike shooting a firearm, lashing out with an edged weapon is a primitive, instinctive action that a subject can accomplish in that 10- to 15-second window. At the beginning of the 20th century while conducting operations in the Philippines, members of the U.S. Marine Corps found that insurgents, although fatally wounded in the chest, still could move forward and issue a final blow from their edged weapons, seriously wounding or killing Marines. These experiences support the FBI data that even after being mortally wounded, a suspect with a knife still can inflict injury or death to an officer.


What can officers do to protect themselves? Identifying the threat of a one-handed opening knife is the first step. Law enforcement agencies should review their policies, procedures, and case law in the formulation of a plan for disarming suspects carrying knives. The greatest tool that officers have in their arsenal is maintaining distance as it gives them time to react to an attack. Because it is not always feasible to stay 30 feet away from a suspect, officers should consider the option of disarming the person and returning the weapon if no further probable cause exists. This may prove problematic as officers encounter resistance from suspects who do not want to relinquish their weapons.


As part of officer training, law enforcement agencies need to establish protocols for disarming suspects before officers interview them. Ideally, this process would involve two officers--with at least one being armed with a less lethal weapon in the event that the situation deteriorates--as the other officer tries to disarm the suspect. At no time should officers allow subjects to touch their weapons or take them out of their pockets, even if they offer to remove them and place them on the ground. Once suspects have made contact with their knives, they can quickly transition to opening the blade and assaulting the officer, with potentially deadly consequences. In one study, for example, 45 percent of edged-weapon attacks resulted in death from a single stab or slash. (16)


Based on prior years of law enforcement assault data, the profession knows that over a thousand officers will face an edged weapon in the next 12 months. Equally recognized is the fact that it may not always be possible to place a suspect outside the danger zone. Law enforcement encounters tend to take place face-to-face, which may give a subject an advantage in an edged-weapon encounter. Consequently, officers need to be aware of the presence of knives and other edged weapons to reduce the delay in their reaction times.


While ballistic body armor provides a degree of protection against slash attacks, most modern pocketknives have the ability to puncture the material unless the weapon strikes a trauma plate. Furthermore, vests do not protect vulnerable targets, such as the carotid and brachial arteries, that can lead to unconsciousness or death if severed. The subclavian and femoral regions also are exposed and can be vulnerable to an edged weapon with a blade length less than 3 inches. However, with proper preplanning, officers can substantially reduce their exposure to an edged-weapon attack. They must recognize all edged weapons as threats and neutralize them before such weapons reach their intended targets.


(1) For example, B.B. Ong, "The Pattern of Homicidal Slash/Chop Injuries: A 10-Year Retrospective Study in University Hospital Kuala Lumpur," Journal of Clinical Forensic Medicine 6 (1999): 24-29; and D.A. Rouse, "Patterns of Stab Wounds: A 6-Year Study," Medicine, Science, and the Law 34 (1994): 67-71.

(2) Supra note 1 (Rouse); and A.C. Hunt and R.J. Cowling, "Murder by Stabbing," Forensic Science International 52 (1991): 107-112.

(3) A. Bleetman, H. Hughes, and V. Gupta, "Assailant Technique in Knife Slash Attacks," Journal of Clinical Forensic Medicine 10 (2003): 1-3; and A. Bleetman, C.H. Watson, I. Horsfall, and S.M. Champion, "Wounding Patterns and Human Performance in Knife Attacks: Optimizing the Protection Provided by Knife-Resistant Body Armor," Journal of Clinical Forensic Medicine 10 (2003): 243-248.

(4) E. Webb, J.P. Wyatt, J. Henry, and A. Busuttil, "A Comparison of Fatal with Nonfatal Knife Injuries in Edinburgh," Forensic Science International 99 (1999): 179-187.

(5) Supra note 1 (Rouse).

(6) Supra note 2 (Hunt and Cowling).

(7) L.A. Murray and M.A. Green, "Hilts and Knives: A Survey of 10 Years of Fatal Stabbings," Medicine, Science, and the Law 27, no. 3 (1987): 182-184.

(8) Supra note 1 (Ong).

(9) U.S. Department of Justice, Federal Bureau of Investigation, Law Enforcement Officers Killed and Assaulted, annually from 1993 through 2002, (Washington, DC, 2003).

(10) M.A. Green, "Stab Wound Dynamics: A Recording Technique for Use in Medico-Legal Investigations," Journal Forensic Science Society 18, nos. 3 and 4 (1978): 161-163.

(11) W. Hern, W. Glazebrook, and M. Beckett, "Reducing Knife Crime," British Medical Journal 330 (2005): 1221-1222.

(12) B. Knight, "The Dynamics of Stab Wounds," Forensic Science 6 (1975): 249-255.

(13) Supra note 10, 162.

(14) F. Borelli, "Twenty-one Feet Is Way Too Close," Law Enforcement Trainer, July/August 2001, 12-15.

(15) U.S. Department of Justice, Federal Bureau of Investigation, Firearms Training Unit, FBI Academy, Handgun Wounding Factors and Effectiveness (Quantico, VA, July 14, 1989).

(16) Supra note 4.


Mr. Thompson is the program manager of the Center for Excellence in Public Safety and Law Enforcement at Florida Gulf Coast University in Fort Myers.

Dr. Mesloh is the director of the Institute for Technological Innovation and Research at Florida Gulf Coast University in Fort Myers.
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Article Details
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Author:Mesloh, Charlie
Publication:The FBI Law Enforcement Bulletin
Geographic Code:1USA
Date:Mar 1, 2006
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