Non-lethal weapons, some of which are also called less-lethal weapons, less-than-lethal weapons, non-deadly weapons, pain-inducing weapons or, more recently, compliance weapons are weapons intended to be less likely to kill a living target than are conventional weapons. These various terms are meant to describe the intended result of applying these technologies, techniques and procedures; accidental, incidental, and correlative casualties are possible and an understood and accepted risk wherever force is applied. Non-lethal weapons are used in combat situations to limit the escalation of conflict or where employment of lethal force is prohibited or undesirable or where rules of engagement require minimum casualties or policy restricts the use of conventional force. Non-lethal weapons may be used by conventional military in a range of missions across the force continuum. Non-lethal weapons may also be utilized by military police, by United Nations forces, and by occupation forces for peacekeeping and stability operations. Non-lethal weapons may be used to channelize a battlefield or control the movement of civilian populations or limit civilian access to restricted areas (as they were utilized by the U.S.M.C.'s 1st Marine Expeditionary Force in Somalia in 1995). When used by police forces domestically, similar weapons, tactics, techniques and procedures are often called "less lethal" or "less than lethal" and are employed in riot control, prisoner control, crowd control, refugee control, and self-defense.
In the past, military and police faced with undesirable escalation of conflict had few acceptable options. Military personnel guarding embassies often found themselves restricted to unloaded weapons. National guards or policing forces charged with quelling riots were able to use only truncheons or similar club-like weapons, or bayonet or saber charges, or fire live ammunition at crowds. In the late 1980s and early 1990s, the Non-lethality Policy Review Group at U.S. Global Strategy Council in Washington and other independent think tanks around the world called for a concerted effort to develop weapons that were more life-conserving, environmentally friendly, and fiscally responsible than weapons available at that time. The futurists Alvin Toffler and Heidi Toffler reported comprehensively on this phase of the history of non-lethal weapons in Chapter 15 of their 1993 book, War and Anti-War. The U.S. Congress and other governments agreed and began an organized development of non-lethal weapons to provide a range options between talking and shooting. Recognizing the need to limit the escalation of force, research and development of a range of non-lethal weapons has since been undertaken internationally by governments and weapons manufacturers to fill the need for such weapons. Some non-lethal weapons may provide more effective riot control than firearms, truncheons or bayonets with less risk of loss of life or serious injury. Before the general availability of early military non-lethal weapons in the mid 1990s, war-fighters had few or no casualty-limiting options for the employment of scalable force and were continually at risk whenever lethal force was prohibited during sensitive missions.
In 2001 the United States Marine Corps revealed its development of a less-than-lethal energy weapon called the Active Denial System, a focused millimeter wave device said to be capable of heating all living matter in the target area rapidly and continuously for the duration of the beam, causing transient intolerable pain but no lasting damage. The skin temperature of a person subjected to this weapon can jump to approximately 130 °F (54 °C) in as little as 2 seconds depending on the skin's starting temperature. The system is nonlethal (the penetration of the millimeter wave beam into human skin is only a few millimeters).
In 2004 author Jon Ronson cited an unclassified military report titled "Non-Lethal Weapons: Terms and References" 21 acoustic weapons were listed, in various stages of development, including the Infrasound ("Very low-frequency sound which can travel long distances and easily penetrate most buildings and vehicles...biophysical effects are projected to be: nausea, loss of bowels, disorientation, vomiting, potential internal organ damage or death may occur. Superior to ultrasound...)", however no such effects had been achieved as of 2002[update].
Until the development of non-lethal weapons, police officers around the world had few if any non-lethal options for riot control. Common tactics used by police that were intended to be non-lethal or less lethal included a slowly-advancing wall of men with batons, officers on horses trained to deal with policing situations, or a charge into a riot using the flats of sabers. Other reasonably successful approaches included shotguns with lower-powered cartridges, "salt shells", and ricocheting the shot off of the ground. In the mid 1900s, with the integration of fire-control systems into major cities, police found that high-pressure fire hoses could be effective in dispersing a crowd (the use of water cannons and fire trucks has remained an effective nonlethal tactic to disperse riots). Trained police dogs were also commonly used to scare and disperse rioters and apprehend individuals. In the 1980s the development of the high-tensile plastics Kevlar and Lexan revolutionized personal armor and shields, and led to new tactics for riot squads and other special-purpose teams. Officers could now stand up against violent rioters throwing dangerous projectiles without having to resort to lethal methods to quickly disperse the danger. Coupled with the introduction of effective non-lethal chemical agents such as tear gas and offensive odor canisters, and non-lethal impact rounds such as rubber bullets and "bean bag" flexible baton rounds, riot tactics were modified to rely less on violent response to attacking rioters than on a return to the slowly-advancing wall, with supporting officers firing non-lethal ordnance into the crowd to discourage advance.
Police officers on patrol were traditionally armed with a baton or pistol or both, and non-lethal methods of subduing an attacker centered on hand-fighting techniques such as Jujutsu and baton use. In the 1980s and 1990s officers began deploying non-lethal personal sidearms such as pepper sprays, and eventually electroshock weapons such as Tasers, which were developed for use by police and also found a market in self-defense by private citizens. However, these weapons were developed for non-lethal resolution of a one-on-one conflict.
During the 1990s and early 2000s interest in various other forms of less-than-lethal weapons for military and police use rose. Amongst other factors, the use of less-than-lethal weapons may be legal under international law and treaty in situations where weapons such as aerosol sprays or gases defined as chemical are not. Less-than-lethal weapons are also useful in keeping the peace in the aftermath of violent conflict.
In the late 1990s and early 2000s police began to adopt a new pepper spray delivery system based on the equipment used in paintballs. A specialized paintball, called a "pepperball", is filled with liquid or powdered capsaicin, the active ingredient in pepper spray, and is propelled by compressed gas using a paintball marker similar to those used for the sport but operating at higher pressure. The impact of the capsule is immediately painful (a pepperball's shell is thicker than a standard paintball and is fired at higher velocity), and it breaks open on impact, dispersing the capsaicin with similar effect to aerosol-delivered pepper spray. However, to be most effective, pepper spray must contact the eyes, nose, or mouth of the target; pepper spray on clothing or tougher skin has a much reduced effect.
Vessel and vehicle stoppers include a wide range of methods and devices meant to disable a vessel or vehicle to prevent attack by an oncoming vessel or vehicle or to stop that vessel or vehicle for evaluation. Vessel and vehicle stoppers may include kinetic, chemical, or electromagnetic means.
Caltrops are known to have been in use since Roman times and may have been used earlier: the concept was familiar to the 4th century BC Greeks, who used rocks, brush, nets and trees placed in the path of enemy conveyances on land or ensnarement devices hidden under water to achieve the same result: stop the enemy or suspected hostile in his tracks for examination or to prevent or limit incursions. Contemporary caltrops look something large jacks from the childhood game. Placed in the path of oncoming wheeled or tracked vehicles, they are meant to foul wheels, destroy tires and tracks, and incapacitate vehicles.
Increasingly, combat vehicles, such as the urban variant of the Leopard 2 main battle tank, are being fitted with non-lethal weapons. The pictured Humvee has be fitted with the Active Denial System. A dish that projects electromagnetic radiation just powerful enough to penetrate human skin and make the nervous system think the victim is on fire although no physical damage is done. Future combat vehicles such as the American GCV Infantry Fighting Vehicle will incorporate non-lethal weapons.
Non-lethal weapons are intended to minimize injury or death. While people are occasionally seriously injured or killed by these weapons, fatalities are relatively infrequent. Causes of death from non-lethal weapons are varied and occasionally uncertain. Misplaced or ricocheting shots, pre-existing medical conditions, inadequate user training, repetitive applications and intentional misuse have been implicated in different cases where death has occurred.
As different parts of the body differ in vulnerability, and because people vary in weight and fitness, any weapon powerful enough to incapacitate may be capable of killing under certain circumstances. Thus "non-lethal force" does have some risk of causing death: in this context "non-lethal" means only "not intended to kill".
Several groups maintain there is great room for improvement in non-lethal weapons and procedures for their use. Claims for the relative safety of such weapons are usually contingent on their being used "properly." For example, the rubber bullets developed during the 1960s were supposed to be fired at the ground and hit the target only after ricochet, and other non-lethal bullets are designed to be fired at the lower body; they can be lethal if fired directly at the head, as commonly happens.
Non-lethal rounds are firearm rounds which are designed to incapacitate, but not kill, a target. The rounds rely on the transfer of kinetic energy to accomplish this incapacitation. Rubber bullets, wax bullets, plastic bullets, beanbag rounds, and rubber bullets with electroshock effect (e.g. Taser XREP rounds) are less lethal than conventional metal bullets, and are also propelled at lower speed. (Gunpowder is not used, only a percussion cap.) "Bean bag" type bullets are sometimes referred to as flexible baton rounds. More recently, high-velocity paintball guns are also used to launch less-lethal rounds, including the FN 303 launcher and PepperBall commercial products. There is also the Variable Velocity Weapon Concept, for which a propulsion energy source may not yet have been clearly established and/or finalized. In any case, all of these technologies apply the same basic mechanism, which is to launch a mass at the target that interacts kinetically.
Because the impact energy varies based on engagement range, it is accepted that non-lethal ammunition in some scenarios may cause injury. The risk of adverse effects: contusions, abrasions, broken ribs, concussions, loss of eyes, superficial organ damage, serious skin lacerations, massive skull fractures, rupture of the heart or kidney, fragmentation of the liver, hemorrhages, and death are considerable. Policies for determining if medical assistance should be contacted immediately after an actual deployment of a non-lethal munition (even if no physical injuries appear on subject or subjects) are usually determined by the organization using such devices. There is currently no universal-consensus policy paper to suggest an alternative.
Hand grenades come in several less-lethal varieties, such as "flashbang" (stun) grenades, "sting" grenades with rubber shrapnel, and grenades designed to release chemical irritants (described below).
Water cannons are commonly used in crowd and riot control, for dispersal or to prevent movement on a particular position. Water-filled rounds for small arms are in experimental stages.
Unlike less-than-lethal rounds that rely mostly on the kinetic energy of the projectile to incapacitate the opponent, darts use sedative agents to incapacitate the target. Darts have been used for centuries in wildlife parks and zoos to incapacitate large and/or dangerous animals (e.g. leopards, tigers, elephants) in order to transport them. Darts can be fired with repeating crossbows, compressed air rifles or blowpipes, or with electromagnets as used by the Gauss pistol.
Malodorants produce smells so horrible they cause people to leave the affected area. In 2008 The Israeli Defence Forces have begun using Skunk for crowd control. It is a form of mist sprayed from a water cannon, which leaves a terrible odor of rot or sewage on whatever it touches, and does not wash off easily.
The active ingredient in pepper spray is oleoresin capsicum (OC), a spicy chemical derived from burning-hot cayenne pepper plants.
An estimate by the International Association of Chiefs of Police suggested at least 113 pepper spray related fatalities had occurred in the United States, mostly from positional asphyxia, which is caused by airway-restrictive immobilizing holds. Such holds can be exacerbated by the use of pepper spray and the resulting airway inflammation.
The use of chemical weapons such as tear gas (CS) and pepper spray (OC) has come under increasing scrutiny and criticism due to studies showing serious long term side effects. Many police forces are no longer exposing their members to the chemicals during training. Additionally, tear gas and pepper spray are banned in warfare by the international Chemical Weapons Convention.
Journalist Rubén Salazar was killed in Los Angeles in 1970 by an errant CS gas canister during the Chicano riots.
There have been accusations that the use of (inflammable) CS gas canisters during the Waco siege in 1993 contributed to the fire that killed many Branch Davidians.
Often promoted for self defense, mace is a spray of various formulations, that may include tear gas, pepper spray, and phenacyl chloride (CN).
Psychochemical weapons are psychoactive drugs, such as BZ, LSD, Kolokol-1, EA-3167, and methamphetamine designed to have a disorienting effect when used during combat or interrogation.
Blister agents, including CR gas, are less often used riot control agents. Other irritants include CS gas and nonivamide (PAVA).
Sticky foam was tried by the U.S. Marine Corps in the peacekeeping Operation United Shield in 1995 with some success, but as a result various complications in its field use were also discovered.
Electroshock weapons are incapacitant weapons used for subduing a person by administering electric shock aimed at disrupting superficial muscle functions. One type is a conductive energy device (CED), an electroshock gun popularly known by the brand name "Taser", which fires projectiles that administer the shock through a thin, flexible wire. Other electroshock weapons such as stun guns, stun batons, and electroshock belts administer an electric shock by direct contact.
Directed energy weapons are weapons that emit energy in an aimed direction without the means of a projectile. They are non-lethal and can immobilize people as well as machines (e.g. vehicles). Directed energy weapons include electromagnetic weapons, (including laser weapons), particle beam weapons, and sonic weapons.
In the United States of America, the University of Texas-Austin Institute for Advanced Technology (IAT) conducts basic research to advance electrodynamics and hypervelocity physics related to electromagnetic weapons. Although generally considered 'non-lethal weapons', electromagnetic weapons do pose health threats to humans. In fact, "non-lethal weapons can sometimes be deadly."
United States Department of Defense policy explicitly states that non-lethal weapons "shall not be required to have a zero probability of producing fatalities or permanent injuries." Although a Human Effects Advisory Panel was established in 1998 to provide independent assessment on human effects, data, and models for the use of 'non-lethal weapons' on the general population, the TECOM Technology Symposium in 1997 concluded on non-lethal weapons: "Determining the target effects on personnel is the greatest challenge to the testing community," primarily because "the potential of injury and death severely limits human tests." However, "directed energy weapons that target the central nervous system and cause neurophysiological disorders" may violate the Convention on Certain Conventional Weapons of 1980. And weapons that go beyond non-lethal intentions and cause "superfluous injury or unnecessary suffering" could violate the Protocol I to the Geneva Conventions of 1977." Safety and evaluation of the physical and psychological effects of the long-term or repetitive uses of the pain-inducing non-lethal weapons on humans have not been well understood or studied in any great details. Any such studies require explicit consent of all participants so as not to violate the UN Convention against torture and other cruelties.
Both pepper spray and electroshock weapons have been misused in so-called "pain compliance" techniques against people attempting to practice nonviolent civil disobedience. For instance, pepper spray has been swabbed directly into the eyes of protesters who were being held immobile with their eyelids forcibly pulled back. Amnesty International in 1997 released a report titled USA: Police use of pepper spray is tantamount to torture. The repetitive use of pain-inducing non-lethal weapons on a human may be considered cruel, if not torture by itself. Such use is likely to be considered abusive or in violation of the 1984 United Nations Convention against torture and other cruelties.
Loren Thompson, chief operating officer of the Lexington Institute in Virginia states that: "The relevant (electromagnetic weapon) technology is well within the grasp of some countries and transnational terrorist groups", and further states that U.S. hardware is susceptible to microwave and other directed-energy weapons.
Suitable materials and tools to create electromagnetic weapons are commonly available. "The threat of electromagnetic bomb proliferation is very real."
Also, electroshock weapons can be easily made DIY. Reports have been made of people making tasers from cell phones and other electrical devices.