Riot control measures are used by

law enforcement Law enforcement is the activity of some members of government who act in an organized manner to enforce the law by discovering, deterring, rehabilitating, or punishing people who violate the rules Rule or ruling may refer to: Education ...

military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct ...

, paramilitary or

security forces Security forces are statutory organizations with internal security mandates. In the legal context of several nations, the term has variously denoted police and military units working in concert, or the role of military and paramilitary forces (su ...

to control, disperse, and arrest people who are involved in a riot, unlawful demonstration or unlawful

protest A protest (also called a demonstration, remonstration or remonstrance) is a public expression of objection, disapproval or dissent towards an idea or action, typically a political one. Protests can be thought of as acts of cooper ...

. If a riot is spontaneous and irrational, actions which cause people to stop and think for a moment (e.g. loud noises or issuing instructions in a calm tone) can be enough to stop it. However, these methods usually fail when there is severe anger with a legitimate cause, or the riot was planned or organized. Riot control personnel have long used less lethal weapons such as batons and whips to disperse crowds and detain rioters. Since the 1980s, riot control officers have also used

tear gas Tear gas, also known as a lachrymator agent or lachrymator (), sometimes colloquially known as "mace" after the early commercial aerosol, is a chemical weapon that stimulates the nerves of the lacrimal gland in the eye to produce tears. In ...

pepper spray Pepper spray, oleoresin capsicum spray, OC spray, capsaicin spray, or capsicum spray is a lachrymatory agent (a compound that irritates the eyes to cause a burning sensation, pain, and temporary blindness) used in policing, riot control, ...

rubber bullet Rubber bullets (also called rubber baton rounds) are a type of baton round. Despite the name, rubber bullets typically have either a metal core with a rubber coating, or are a homogeneous admixture with rubber being a minority component. Alth ...

s, stun grenades, and electric

taser A taser is an electroshock weapon used to incapacitate people, allowing them to be approached and handled in an unresisting and thus safe manner. It is sold by Axon, formerly TASER International. It fires two small barbed darts intended t ...

s. In some cases, riot squads may also use

Long Range Acoustic Device A long-range acoustic device (LRAD) is an acoustic hailing device (AHD), sound cannon and sonic weapon developed by Genasys. It has been used as a method of crowd control, which has caused permanent hearing damage, having an extremely high ...

water cannon A water cannon is a device that shoots a high-velocity stream of water. Typically, a water cannon can deliver a large volume of water, often over dozens of meters. They are used in firefighting, large vehicle washing, riot control, and mining ...

armoured fighting vehicle An armoured fighting vehicle (AFV) is an armed combat vehicle protected by armour, generally combining operational mobility with offensive and defensive capabilities. AFVs can be wheeled or tracked. Examples of AFVs are tanks, armoured cars, ...

s, aerial surveillance, police dogs or

mounted police Mounted police are police who patrol on horseback or camelback. Their day-to-day function is typically picturesque or ceremonial, but they are also employed in crowd control because of their mobile mass and height advantage and increasingly in t ...

on horses. Persons performing riot control typically wear protective equipment such as riot helmets, face visors, body armor (vests, neck protectors, knee pads, etc.), gas masks and

riot shield A riot shield is a lightweight protection device, typically deployed by police and some military organizations, though also utilized by protestors. Riot shields are typically long enough to cover an average-sized person from the top of the head to ...

s. There have been cases where lethal weapons are used to violently suppress a protest or riot, as in the

Boston Massacre The Boston Massacre (known in Great Britain as the Incident on King Street) was a confrontation in Boston on March 5, 1770, in which a group of nine British soldiers shot five people out of a crowd of three or four hundred who were harassing t ...

Haymarket Massacre The Haymarket affair, also known as the Haymarket massacre, the Haymarket riot, the Haymarket Square riot, or the Haymarket Incident, was the aftermath of a bombing that took place at a labor demonstration on May 4, 1886, at Haymarket Square in ...

, Banana Massacre,

Hungarian Revolution of 1956 The Hungarian Revolution of 1956 (23 October – 10 November 1956; hu, 1956-os forradalom), also known as the Hungarian Uprising, was a countrywide revolution against the government of the Hungarian People's Republic (1949–1989) and the Hunga ...

Kent State Shootings The Kent State shootings, also known as the May 4 massacre and the Kent State massacre,"These would be the first of many probes into what soon became known as the Kent State Massacre. Like the Boston Massacre almost exactly two hundred years bef ...

, Soweto Uprising, Mendiola Massacre,

Bloody Sunday (1905) Bloody Sunday or Red Sunday ( rus, Крова́вое воскресе́нье, r=Krovávoe voskresénje, p=krɐˈvavəɪ vəskrʲɪˈsʲenʲjɪ) was the series of events on Sunday, in St Petersburg, Russia, when unarmed demonstrators, led by ...

Ponce massacre The Ponce massacre was an event that took place on Palm Sunday, March 21, 1937, in Ponce, Puerto Rico, when a peaceful civilian march turned into a police shooting in which 19 civilians and two policemen were killed, and more than 200 civilians ...

Bloody Sunday (1972) Bloody Sunday, or the Bogside Massacre, was a massacre on 30 January 1972 when British soldiers shot 26 unarmed civilians during a protest march in the Bogside area of Derry, Northern Ireland. Fourteen people died: thirteen were killed outr ...

1989 Tiananmen Square protests The Tiananmen Square protests, known in Chinese as the June Fourth Incident (), were student-led demonstrations held in Tiananmen Square, Beijing during 1989. In what is known as the Tiananmen Square Massacre, or in Chinese the June Fourth ...

2017 Venezuelan protests The 2017 Venezuelan protests were a series of protests occurring throughout Venezuela. Protests began in January 2017 after the arrest of multiple opposition leaders and the cancellation of dialogue between the opposition and Nicolás Maduro's g ...

, 2018–2019 Gaza border protests, Citizenship Amendment Act protests, 2022 Sri Lankan protests and

Mahsa Amini protests Civil unrest and protests against the government of Iran associated with the death in police custody of Mahsa Amini ( fa, مهسا امینی) began on 16 September 2022 and are ongoing as of December 2022. Amini had been arrested by the Guida ...

History

Maintaining order during demonstrations and quenching riots has always been a challenge for governments and administrations. Until early in the 20th century, no dedicated force really existed in most countries and the traditional response when the regular police force proved inadequate was to call upon the army, often with disastrous results: either

fraternization Fraternization (from Latin ''frater'', brother) is "to become brothers" by conducting social relations with people who are actually unrelated and/or of a different class (especially those with whom one works) as if they were siblings, family memb ...

or use of excessive violence. The terminology arguably first arises in the

Keystone Cops The Keystone Cops (often spelled "Keystone Kops") are fictional, humorously incompetent policemen featured in silent film slapstick comedies produced by Mack Sennett for his Keystone Film Company between 1912 and 1917. History The idea for th ...

short " A Hash House Fraud" in 1915. In France, for example, several revolts were fueled by poor handling by the military. The

National Gendarmerie The National Gendarmerie (french: Gendarmerie nationale, ) is one of two national law enforcement forces of France, along with the National Police. The Gendarmerie is a branch of the French Armed Forces placed under the jurisdiction of the Mini ...

created specialized "mobile" gendarmerie forces several times during the 19th century in times of trouble but these units were disbanded soon after the end of the troubles they had been tasked to handle and there was no permanent organization in place until it was finally decided in 1921 to create "Mobile Gendarmerie platoons" within the Departmental Gendarmerie. These platoons, either horse mounted or on foot were composed of 40 gendarmes each (60 in the Paris Region). In 1926, the platoons formed the "Garde Républicaine mobile" (mobile republican guard or GRM), which became a distinct branch of the Gendarmerie in 1927, the platoons becoming part of companies and legions. By 1940, the GRM was a force 21,000 strong, composed of 14 Légions, 54 company groups and 167 companies. Long the only large force specialized in maintaining or restoring law and order in France during demonstrations or riots, the GRM progressively developed the doctrine and skills needed in that role: exercise restraint, avoid confrontation as long as possible, always leave an "exit door" for the crowd, etc. In 1940, after the fall of France, the German authorities had the GRM disbanded but it was reinstated in 1944 and renamed

Mobile Gendarmerie The Mobile Gendarmerie (french: Gendarmerie mobile) (GM) is a subdivision of the French National Gendarmerie whose main mission is to maintain public order (from crowd control to riot control) and general security. Contrary to the Departmental G ...

in 1954.

The first squad trained in modern techniques of riot control in Asia was formed in 1925 in

colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 au ...

Shanghai Shanghai (; , , Standard Mandarin pronunciation: ) is one of the four direct-administered municipalities of the People's Republic of China (PRC). The city is located on the southern estuary of the Yangtze River, with the Huangpu River flowin ...

as a response to the mismanaged riot of the

May Thirtieth Movement The May Thirtieth Movement () was a major labor and anti-imperialist movement during the middle-period of the Republic of China era. It began when the Shanghai Municipal Police opened fire on Chinese protesters in Shanghai's International Settl ...

. New policing methods, including

combat pistol shooting Combat pistol shooting is a modern martial art that focuses on the use of the handgun as a defensive weapon for self defense, or for military and police use. Like most martial arts, combat pistol shooting is practiced both for defense and for sport. ...

hand to hand combat Hand-to-hand combat (sometimes abbreviated as HTH or H2H) is a physical confrontation between two or more persons at short range (grappling distance or within the physical reach of a handheld weapon) that does not involve the use of weapons.Huns ...

skills, and

knife fight A knife fight is a violent physical confrontation between two or more combatants in which one or more participants is armed with a knife.MacYoung, Marc, ''Winning A Street Knife Fight'', (Digital format, 70 min.), Boulder, CO: Paladin Press, (J ...

training, were pioneered by British Assistant Commissioner William E. Fairbairn and officer Eric Anthony Sykes of the

Shanghai Municipal Police The Shanghai Municipal Police (SMP; ) was the police force of the Shanghai Municipal Council which governed the Shanghai International Settlement between 1854 and 1943, when the settlement was retroceded to Chinese control. Initially composed of ...

as a response to a staggering rise in armed crime in the

had become one of the world's most dangerous cities due to a breakdown in law and order in the country and the growth of

organised crime Organized crime (or organised crime) is a category of transnational, national, or local groupings of highly centralized enterprises run by criminals to engage in illegal activity, most commonly for profit. While organized crime is generally th ...

and the

opium trade Opium (or poppy tears, scientific name: ''Lachryma papaveris'') is dried latex obtained from the seed capsules of the opium poppy ''Papaver somniferum''. Approximately 12 percent of opium is made up of the analgesic alkaloid morphine, which i ...

. Under Fairbairn, the SMP developed a myriad of riot control measures. These riot control techniques led to the introduction of Shanghai's "Reserve the first modern SWAT team. As a reserve unit, it was used to forcibly disband riots as well as to respond to high-level criminality like kidnappings and armed robberies. The skills developed in Shanghai have been adopted and adapted by both international police forces and clandestine warfare units. William Fairbairn was again the central figure, not only leading the Reserve Unit, but teaching his methods around the world, including in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

, and the colonial regimes of

Cyprus Cyprus ; tr, Kıbrıs (), officially the Republic of Cyprus,, , lit: Republic of Cyprus is an island country located south of the Anatolian Peninsula in the eastern Mediterranean Sea. Its continental position is disputed; while it is ge ...

and

Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, bor ...

Equipment

For protection, officers that are trained in police anti-riot schools performing riot control will often wear protective helmets and carry riot shields. These are designed to protect the wearer from those dangers that come from direct

melee A melee ( or , French: mêlée ) or pell-mell is disorganized hand-to-hand combat in battles fought at abnormally close range with little central control once it starts. In military aviation, a melee has been defined as " air battle in which ...

and hurled objects such as bottles and bricks. The gear frequently worn by riot control officers protects the entire body with no vulnerable spots to exploit. For example, the helmets worn by riot control officers have an additional outward-extending part that protects the back of the neck from assault. To provide even greater protection, the protective equipment often provides ballistic protection. If tear gas or other riot control agents are to be used, gas masks may also be worn. One of many additional concerns is to prevent people in the crowd from snatching officers' side arms, which may be stolen or even used against the police. In a very heavy crowd, the officer may not be able to see who is responsible for snatching a weapon, and may not even notice that it has happened. For this reason, riot police may have holsters with positive locking mechanisms or other extra means of retention, if their agencies can afford such tools. However, this can be a trade-off that increases the amount of time needed to draw the sidearm in an emergency. Alternately, riot police may not carry sidearms at all. The initial choice of

tactics Tactic(s) or Tactical may refer to: * Tactic (method), a conceptual action implemented as one or more specific tasks ** Military tactics, the disposition and maneuver of units on a particular sea or battlefield ** Chess tactics ** Political tact ...

determines the type of offensive equipment used. The base choice is between

lethal Lethality (also called deadliness or perniciousness) is how capable something is of causing death. Most often it is used when referring to diseases, chemical weapons, biological weapons, or their toxic chemical components. The use of this ter ...

(e.g. 12 gauge shotgun) and

less-than-lethal weapon Non-lethal weapons, also called nonlethal weapons, less-lethal weapons, less-than-lethal weapons, non-deadly weapons, compliance weapons, or pain-inducing weapons are weapons intended to be less likely to kill a living target than conventional ...

ry (e.g.

plastic bullet A plastic bullet or plastic baton round (PBR) is a non-lethal projectile fired from a specialised gun. Although designed as a non-lethal weapon, they have caused a number of deaths when used incorrectly. Plastic bullets are generally used for ...

s, batons, and other incapacitants). The decision is based on the perceived level of threat and the existing laws; in many countries it is illegal to use lethal force to control riots in all but the most extreme circumstances. Special riot hand weapons include the wooden or rubber baton; the African

sjambok The sjambok () or litupa is a heavy leather whip. It is traditionally made from an adult hippopotamus or rhinoceros hide, but is also commonly made out of plastic. A strip of the animal's hide is cut and carved into a strip long, tapering fro ...

, a heavy leather or plastic whip, and the Indian lathi, a long cane with a blunt metal tip. Vehicle-mounted

s may serve to augment personal weapons. Some water cannons let police add dye to mark rioters or tear gas to help disperse the crowds. In major unrest, police in armoured vehicles may be sent in following an initial subduing with firepower. Occasionally, police dogs, fire hoses, or

are deployed. File:Bastille 2007-05-06 anti Sarkozy 487645689 c9fce856e3 o.jpg, French gendarmes mobiles using tear gas File:Bastille 2007-05-06 anti Sarkozy 487623928 37656cd319 o.jpg, This gendarme is shooting tear gas canisters using an Alsetex "Cougar" launcher File:Vietnamprotestors.jpg,

U.S. Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, cl ...

troops are shown attempting to keep Vietnam War protesters from rioting in

Washington, D.C. ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, ...

, 1967. File:VOA Arrott - A View of Syria, Under Government Crackdown 07.jpg, Syrian riot control in Damascus in 2012 File:Warszawa, Marsz Niepodległości 2011 05.jpg, Polish riot control police in

Warsaw Warsaw ( pl, Warszawa, ), officially the Capital City of Warsaw,, abbreviation: ''m.st. Warszawa'' is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland, and its population is officia ...

at the March of Independence in 2011 File:Riot police by the building of the Cabinet of Ministers.jpg, Defensive line of "Berkut" unitmen in

riot gear Riot control measures are used by law enforcement, military, paramilitary or security forces to control, disperse, and arrest people who are involved in a riot, unlawful demonstration or unlawful protest. If a riot is spontaneous and irration ...

by the Cabinet of Ministers building in

Kyiv Kyiv, also spelled Kiev, is the capital and most populous city of Ukraine. It is in north-central Ukraine along the Dnieper River. As of 1 January 2021, its population was 2,962,180, making Kyiv the seventh-most populous city in Europe. Kyi ...

during 2013 Euromaidan protests. File:Policiais Manifestacoes 20170209.jpg, Riot control group of Rio de Janeiro Police in confrontation with protesters in the historical center of the city. File:Reparto Celere.jpg, Italian ''Celerini'' in the 1950s. File:Police Protesters Clash after Eid Prayers in Kashmir 2 Sept 2017 29.jpg, Pellet shotguns have been used by Indian security forces for

crowd control in Jammu and Kashmir Crowd control in Jammu and Kashmir is a public security practice to prevent and manage violent riots. It is enforced by police forces through laws preventing unlawful assembly, as well as using riot control agents such as tear gas, chili grenade ...

against

stone pelting Stone throwing or rock throwing, when it is directed at another person (called stone pelting in India), is often considered a form of criminal battery. History The throwing of rocks or stones is one of the most ancient forms of ranged-weapon ...

mobs. File:Water Cannon used on İstiklâl Caddesi near Taksim Square - Gezi Park, İstanbul - Flickr - Alan Hilditch.jpg, Intervention vehicle for social events that interfered with demonstrators in

Gezi Park Taksim Gezi Park is an urban park next to Taksim Square, in Istanbul's Beyoğlu district (historically known as Pera.) It is one of the last green spaces in Beyoğlu and one of the smallest parks of Istanbul. In May 2013, plans to replace the ...

(

Istanbul ) , postal_code_type = Postal code , postal_code = 34000 to 34990 , area_code = +90 212 (European side) +90 216 (Asian side) , registration_plate = 34 , blank_name_sec2 = GeoTLD , blank_i ...

) in 2013

Riot control agent (RCA)

Riot control agents (sometimes called RCAs) are “

non-lethal Non-lethal weapons, also called nonlethal weapons, less-lethal weapons, less-than-lethal weapons, non-deadly weapons, compliance weapons, or pain-inducing weapons are weapons intended to be less likely to kill a living target than conventional ...

lachrymatory agent Tear gas, also known as a lachrymator agent or lachrymator (), sometimes colloquially known as "mace" after the early commercial aerosol, is a chemical weapon that stimulates the nerves of the lacrimal gland in the eye to produce tears. In ad ...

s “ used for riot control. Most commonly used riot control agents are

and various kinds of tear gas. These chemicals disperse a crowd that could be protesting or rioting, or to clear a building. They can rapidly produce sensory irritation or disabling physical effects which usually disappear within 15 minutes (for tear gas) and up to 2 hours (for pepper spray) following termination of exposure. They can also be used for chemical warfare defense training, although their use in warfare itself is a violation of Article I.5 of the Chemical Weapons Convention. Article II.9 of the CWC specifically authorizes their use for domestic law enforcement.

Pepper spray

The active ingredient in pepper-spray is

capsaicin Capsaicin (8-methyl-''N''-vanillyl-6-nonenamide) ( or ) is an active component of chili peppers, which are plants belonging to the genus ''Capsicum''. It is a chemical irritant for mammals, including humans, and produces a sensation of burnin ...

, which is a chemical derived from the fruit of plants in the ''

Capsicum ''Capsicum'' () is a genus of flowering plants in the nightshade family Solanaceae, native to the Americas, cultivated worldwide for their chili pepper or bell pepper fruit. Etymology and names The generic name may come from Latin , me ...

'' genus, including chilies. Desmethyldihydrocapsaicin, a synthetic analogue of capsaicin also known as pelargonic acid vanillylamide or PAVA, is used in another version of pepper spray known as PAVA spray and used in the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...

. Another synthetic counterpart of pepper spray,

pelargonic acid morpholide 4-Nonanoylmorpholine ''pelargonic acid morpholide, N-nonanoylmorpholine, MPK or МПК (for russian: морфолид пеларгоновой кислоты), or MPAis an amide of pelargonic acid and morpholine. Properties 4-Nonanoylmorpholine ...

, was developed and is widely used in

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-eig ...

. Its effectiveness compared to natural pepper spray is uncertain and it reportedly has caused some injuries. When undesirables threaten an area, such as a riot after a soccer game, riot police are called in to subdue them. In these situations, the police may use pepper spray, or water cannons to neutralize the threat. Pepper spray typically comes in canisters, which are often small enough to be carried or concealed in a pocket or purse. Pepper spray can also be bought concealed in items such as

rings Ring may refer to: * Ring (jewellery), a round band, usually made of metal, worn as ornamental jewelry * To make a sound with a bell, and the sound made by a bell :(hence) to initiate a telephone connection Arts, entertainment and media Film and ...

. There are also pepper spray projectiles available, which can be fired from a paintball gun. Having been used for years against demonstrators, it is increasingly being used by police in routine interventions.

Tear gas

Tear gas is a non-specific term for any

chemical A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., w ...

that is used to temporarily incapacitate through irritation of eyes and/or respiratory system. It is used as a hand-held spray or can be fired in canisters that heat up spewing out an aerosol cloud at a steady rate. Whilst the use of tear gas in warfare is prohibited by various international treatiese.g. the

Geneva Protocol The Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or other Gases, and of Bacteriological Methods of Warfare, usually called the Geneva Protocol, is a treaty prohibiting the use of chemical and biological weapons in ...

of 1925: 'Prohibited the use of "asphyxiating gas, or any other kind of gas, liquids, substances or similar materials"' that most states have signed, however police and private self-defense use is not banned in an international manner. Popular tear gases include the eye irritants ortho-chlorobenzylidene-malononitrile (CS gas), chloroacetophenone (CN gas), and dibenz (b,f)-1,4-oxazepine (CR gas). Among a long list of substances, these three have become of greater importance than the others because of their effectiveness and low risks when used. Today, CS has largely replaced CN as the most widely used tear gas internationally.

Decontamination

At room temperature, tear gases are white solids. They are stable when heated and have low

vapor pressure Vapor pressure (or vapour pressure in English-speaking countries other than the US; see spelling differences) or equilibrium vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phas ...

. Consequently, they are usually dispersed as aerosols. All of them have low

solubility In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solub ...

in water but can be dissolved in several

organic solvent A solvent (s) (from the Latin '' solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid. Water is a solvent for ...

Hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolys ...

of CN is very slow in a water solution, especially if alkali is added. CS is rapidly hydrolyzed in water solution (half-life at pH 7 is about 15 min. at room temperature) and extremely rapid when alkali is added (half-life at pH 9 is about 1 min.). CR is hydrolyzed only to a negligible extent in water solution. CN and CR are, thus, difficult to decompose under practical conditions, whereas CS can easily be inactivated by means of a water solution. Skin is suitably decontaminated of CS and CN gas by thorough washing with soap and water. CS is then decomposed, whereas CN is only removed via soap and water. The effects of CR gas are greatly increased by water, causing any attempt to DECON CR via soap and water to increase the severity and duration of the effects. When decontamination of CR is attempted with soap and water the effects of CR can last up to 48 hours Decontamination of material after contamination with CR gas is not possible for up to 45 days. CS can be decontaminated l with a 5–10 percent soda solution or 2 percent alkaline solution. If this type of decontamination cannot be accomplished (e.g., contaminated rooms and furniture), then the only other means is by intensive air exchange—preferably with hot air. Exposed streets and sidewalks will have toxic and irritating CS powder that will be stirred into the air by traffic and pedestrians long after the cloud has dissipated, and should be washed away with water. In contrast to human beings, domesticated animals generally have lower sensitivity to tear gases. Dogs and horses can therefore be used by police for riot control even when tear gas is used.

Dispensing large quantities

Backpack dispensers for riot control agents, when the intent is to use a larger quantity than possible with grenades, are one type of device used by organizations that might, for example, need to cover a prison yard. Dispensers are also made for attachment to helicopters; see CBU-19.

Tactics

The front-line officers in a riot control are often fully armored and carry weapons such as batons, designed to be in direct contact with the crowd. These officers subdue rioters and subsequently allow the less heavily armoured, more mobile officers to make arrests where it is deemed necessary. In face of a greater threat, the riot police will be backed up with other officers equipped with

riot gun In current usage, a riot gun or less-lethal launcher is a type of firearm used to fire "non-lethal" or "less-lethal" ammunition for the purpose of suppressing riots or apprehending suspects with minimal harm or risk. Less-lethal launchers may ...

s to fire

s or "beanbag" rounds. As a less aggressive step,

may first be sent into the crowd. The might and height offered by the

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...

are combined with its training, allowing an officer to more safely infiltrate a crowd. Usually, when front-facing a riot, officers slowly walk in a line parallel to the riot's front, extending to both its ends, as they noisily and simultaneously march and beat their shields with their batons, to cause fear and psychological effects on the crowd. ASEM-Demonstration Hamburg 006

Since the advent of artillery, straight roads have been of notable importance in city defense and control. Upon coming to power,

Napoleon III Napoleon III (Charles Louis Napoléon Bonaparte; 20 April 18089 January 1873) was the first President of France (as Louis-Napoléon Bonaparte) from 1848 to 1852 and the last monarch of France as Emperor of the French from 1852 to 1870. A nephew ...

built great avenues, referred to as anti-riot streets, into the troublesome quarters of Paris. The wide straight roads also allowed for cavalry charges to subdue rioters. In the United Kingdom, usually when large demonstrations take place that are deemed unstable, the

territorial police force A territorial police force is a police service that is responsible for an area defined by sub-national boundaries, distinguished from other police services which deal with the entire country or a type of crime. In countries organized as federations, ...

responsible for the demonstration in that area will usually deploy Police Support Unit personnel who are trained in riot tactics, along with normal divisional officers. If the demonstration turns violent, police will seal roads and other exits to contain protesters in a single area (known as

kettling Kettling (also known as containment or corralling) is a police tactic for controlling large crowds during demonstrations or protests. It involves the formation of large cordons of police officers who then move to contain a crowd within a li ...

) to prevent widespread damage and wait until the protesters tire. These tactics were seen during the

2009 G-20 London summit protests The 2009 G20 London summit protests occurred in the days around the 2 April 2009 G20 London summit. The summit was the focus of protests from a number of groups over various long-standing and topical issues. These ranged from disquiet over econo ...

and the

2010 student protests in London The 2010 United Kingdom student protests were a series of demonstrations in November and December 2010 that took place in several areas of the country, with the focal point of protests being in central London. Largely student-led, the protests w ...

. Tear gas and other more offensive tactics are used as a last resort. Throughout police will be videoing or photographing protesters for future arrests, "

snatch squad The term "snatch squad" refers to two tactics used by police in riot control and crowd control. In riot control The snatch squad in riot control involves several police officers, usually wearing protective riot gear, rushing forwards—occasionally ...

" tactics might also be used where several police officers, usually in protective riot gear, rush forwards, occasionally in flying wedge formation to break through the front of a crowd, with the objective of snatching one or more individuals from a riot that are attempting to control the demonstration at which they are present; the target may be a leader or a speaker, or someone who seems to be leading the crowd. This tactic was used in the

2011 England Riots The 2011 England riots, more widely known as the London riots, were a series of riots between 6 and 11 August 2011. Thousands of people rioted in cities and towns across England, which saw looting, arson, as well as mass deployment of police ...

, most notably by

Greater Manchester Police Greater Manchester Police (GMP) is the territorial police force responsible for law enforcement within the metropolitan county of Greater Manchester in North West England. , Greater Manchester Police employed 6,866 police officers, 3,524 memb ...

who deployed this tactic in

Manchester city centre Manchester City Centre is the central business district of Manchester in Greater Manchester, England situated within the confines of Great Ancoats Street, A6042 Trinity Way, and A57(M) Mancunian Way which collectively form an inner ring road. ...

on 9 August 2011. A more straightforward tactic police may use is a

baton charge A baton charge is a coordinated tactic for dispersing crowds of people, usually used by police or military in response to public disorder. In South Asia, a long bamboo stick, called ''lathi'' in Hindi, is used for crowd control, and the expres ...

which involves police officers charging at a crowd of people with batons and in some cases, riot shields. They run at the crowd hitting people with their batons, and in some situations use riot shields to push them away. Baton charging is designed to cause the maximum amount of pain, in the hope that they would be compelled to move away from the scene, dispersing the crowd.

Research

Long Range Acoustic Device 500X in New York City

Research into weapons that are more effective for riot control continues. Netguns are non-lethal weapons designed to fire a

net Net or net may refer to: Mathematics and physics * Net (mathematics), a filter-like topological generalization of a sequence * Net, a linear system of divisors of dimension 2 * Net (polyhedron), an arrangement of polygons that can be folded up ...

which entangles the target. Netguns have a long history of being used to capture wildlife, without injury, for research purposes. A netgun is currently in development for

riot control.

Pepper-spray projectile A pepper-spray projectile, also called a pepper-spray ball, pepper-ball, pepper bomb, or pepper-spray pellet is a frangible projectile containing a powdered chemical that irritates the eyes and nose in a manner similar to pepper spray. These pro ...

launchers are projectile

weapon A weapon, arm or armament is any implement or device that can be used to deter, threaten, inflict physical damage, harm, or kill. Weapons are used to increase the efficacy and efficiency of activities such as hunting, crime, law enforcement, ...

s that launch a fragile ball which breaks upon impact and releases an irritant powder called PAVA (capsaicin II) pepper. The launchers are often slightly modified .68 caliber

paintball Paintball is a competitive team shooting sport in which players eliminate opponents from play by hitting them with spherical dye-filled gelatin capsules called paintballs that break upon impact. Paintballs are usually shot using low-energy a ...

guns. Stink bombs are devices designed to create an extremely unpleasant smell for riot control and

area denial An area denial weapon is a defensive device used to prevent an adversary from occupying or traversing an area of land, sea or air. The specific method used does not have to be totally effective in preventing passage (and sometimes is not) as lon ...

purposes. Stink bombs are believed to be less dangerous than other riot control chemicals, since they are effective at low concentrations. Sticky foam weapons are being tested, which cover and immobilize rioters with a gooey foam. Low frequency

sound cannon A long-range acoustic device (LRAD) is an acoustic hailing device (AHD), sound cannon and sonic weapon developed by Genasys. It has been used as a method of crowd control, which has caused permanent hearing damage, having an extremely hig ...

s are weapons of various types that use sound to injure or incapacitate subjects using a focused beam of

sound In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' b ...

infrasound Infrasound, sometimes referred to as low status sound, describes sound waves with a frequency below the lower limit of human audibility (generally 20 Hz). Hearing becomes gradually less sensitive as frequency decreases, so for humans to perce ...

Active denial system The Active Denial System (ADS) is a non-lethal directed-energy weapon developed by the U.S. military, designed for area denial, perimeter security and crowd control. Informally, the weapon is also called the heat ray since it works by heating t ...

s (ADS) are a

directed-energy weapon A directed-energy weapon (DEW) is a ranged weapon that damages its target with highly focused energy without a solid projectile, including lasers, microwaves, particle beams, and sound beams. Potential applications of this technology include w ...

developed by the U.S. military. The ADS directs

electromagnetic radiation In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visible) li ...

, specifically, high-frequency microwave radiation, at a frequency of 95

GHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...

, which causes the water in the upper epidermis to boil, stimulating a "burning" sensation in the nerve endings and generating intense pain. Dazzler lasers are

s that use intense light to cause temporary

blindness Visual impairment, also known as vision impairment, is a medical definition primarily measured based on an individual's better eye visual acuity; in the absence of treatment such as correctable eyewear, assistive devices, and medical treatment� ...

History

Equipment

Riot control agent (RCA)

Pepper spray

Tear gas

Decontamination

Dispensing large quantities

Tactics

Research

See also

Riot control units

Weapons used in riot control

Notes

References

External links