Crowd control in the context of Non-lethal weapons

The Praetorian Guard (Latin: cohortes praetoriae) was the imperial guard of the Imperial Roman army that served various roles for the Roman emperor including being a bodyguard unit, counterintelligence, crowd control and gathering military intelligence.

During the Roman Republic, the Praetorian Guards were escorts for high-ranking political officials (senators and procurators) and were bodyguards for the senior officers of the Roman legions. In 27 BC, after Rome's transition from republic to empire, the first emperor of Rome, Augustus, designated the Praetorians as his personal security escort. For three centuries, the guards of the Roman emperor were also known for their palace intrigues, by whose influence upon imperial politics the Praetorians could overthrow an emperor and then proclaim his successor as the new caesar of Rome. In AD 312, Constantine the Great disbanded the cohortes praetoriae and destroyed their barracks at the Castra Praetoria.

Riot police are police who are organized, deployed, trained or equipped to confront crowds, protests or riots.

Riot police may be regular police officers who act in the role of riot police in particular situations, or they may be separate units organized within or in parallel to regular police forces. Riot police are used in a variety of different situations and purposes. They may be employed to control riots as their name suggests, to disperse or control crowds, to maintain public order or discourage criminality, or to protect people or property. The militarization of modern police has brought militaristic riot gear and new technologies that allow for their duties to expand above normal police duties.

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 weapons such as knives and firearms with metal-projectile ammunition. It is often understood that unintended or incidental casualties are risked wherever force is applied; however, non-lethal weapons minimise the risk of casualties (e.g. serious/permanent injuries or death) as much as possible. Non-lethal weapons are used in policing and combat situations to limit the escalation of conflict where employment of lethal force is prohibited or undesirable, where rules of engagement require minimum casualties, or where policy restricts the use of conventional force. However, these weapons occasionally cause serious injuries or death due to allergic reactions, improper use and/or other factors; for this reason the term "less-lethal" has been preferred by some organizations as it describes the risks of death more accurately than the term "non-lethal", which some have argued is a misnomer.

Non-lethal weapons may be used by conventional military in a range of missions across the force continuum. They may also be used by military police, by United Nations forces, and by occupation forces for peacekeeping and stability operations. Non-lethal weapons may also be used to channelize a battlefield, control the movement of civilian populations, or to limit civilian access to restricted areas (as they were utilized by the USMC's 1st Marine Expeditionary Force in Somalia in 1995). Similar weapons, tactics, techniques and procedures are employed by police forces domestically in riot control, prisoner control, crowd control, refugee control, and self-defense, where the terminology of "less-than-lethal" is often used.

The Internal Troops of the Ministry for Internal Affairs of the Russian Federation (Russian: Внутренние войска Министерства внутренних дел (ВВ МВД), romanized: Vnutrenniye voyska Ministerstva vnutrennikh del (VV MVD)) was a paramilitary force of the Ministry of Internal Affairs of Russia from 1991 to 2016.

The Internal Troops was a gendarmerie-like force that supported the Russian police, dealt with crowd control during riots and internal conflicts, and guarded highly-important facilities such as nuclear power plants. The Internal Troops was involved in all conflicts and violent disturbances in modern Russia, including the First and Second Chechen Wars, where it fell under direct military command during wartime and fulfilled missions of local defence and rear area security. The Internal Troops consisted of both volunteers and conscripts, which caused the number of active service members to fluctuate, with less than 200,000 upon their disestablishment from a peak strength of 350,000, and had experienced a shortage of officers since 1998. The final commander-in-chief of the Internal Troops was Colonel General Viktor Zolotov from 2014 to 2016.

The Compagnies républicaines de sécurité (CRS; French: [kɔ̃paɲi ʁepyblikɛn də sekyʁite], Republican Security Corps) are the general reserve of the French National Police. They are primarily involved in general security missions, but the task for which they are best known is crowd and riot control. The DCCRS has seven units: in Paris, Lille, Rennes, Bordeaux, Marseille, Lyon and Metz.

There are 60 "general service" CRS companies, specialized in public order and crowd control; nine "motorway" companies (French: Compagnies autoroutières) specialized in highway patrol in urban areas; and six "zonal" motorcycle units (one per Defense zone.) Two additional companies and several mountain detachments administratively attached to local companies specialize in Mountain Rescue. One company (CRS n°1) specializes in VIP escort. The National Police band is also a CRS unit.

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 the UK for crime prevention and high visibility policing roles. The added height and visibility that the horses give their riders allows officers to observe a wider area, and it also allows people in the wider area to see the officers, which helps deter crime and helps people find officers when they need them. When employed for crowd control, there is a risk that some people may be trampled (resulting in injuries or death). The officer riding the horse may be held legally responsible for injuries depending upon the totality of the circumstances.

Mounted police may be employed for specialized duties ranging from patrol of parks and wilderness areas to riot. For example, in the UK, mounted police are most often seen at football matches. Some mounted police units are trained in search and rescue due to the horse's ability to travel where vehicles cannot.

Barricade (from French barrique 'barrel') is any object or structure that creates a barrier or obstacle to control, block passage or force the flow of traffic in the desired direction. Adopted as a military term, a barricade denotes any improvised field fortification, such as on city streets during urban warfare. These may also include crowd control devices --like temporary traffic barricades, pedestrian barricades, and anti-vehicle barriers-- all of which have also been used in the course of urban protests, counterinsurgency operations, and military operations on urban terrain.

Pepper spray, oleoresin capsicum spray, OC spray, capsaicin spray, mace, or capsicum spray is a lachrymator (tear gas) product containing as its active ingredient the chemical compound capsaicin, which irritates the eyes with burning and pain sensations and so causes them to close, bringing temporary blindness. This blindness allows officers to more easily restrain subjects and permits people in danger to use pepper spray in self-defense for an opportunity to escape. It also causes temporary discomfort and burning of the lungs which causes shortness of breath. Pepper spray is used as a less lethal weapon in policing, riot control, crowd control, and self-defense, including defense against dogs and bears.

Pepper spray was engineered originally for defense against bears, cougars, wolves, and other dangerous predators, and is often referred to colloquially as bear spray.

A long-range acoustic device (LRAD), acoustic hailing device (AHD) or sound cannon is a specialized loudspeaker and sound weapon that produces sound at high power for communicating at a distance. It has been used as a method of crowd control, which has caused permanent hearing damage, having an extremely high decibel capacity (up to 160 dB measured at one meter from the device). Other uses have included for negotiations in siege situations; to deal with piracy at sea; for mass notification during natural disasters or other emergencies; and by the military, including several navies.

Wooden bullets are wooden projectiles designed to be fired from a gun. They are intended to be used as less lethal weapons for crowd control by enforcing pain compliance at a distance. They have been known to raise large welts or bruises on their targets.

A metamaterial (from the Greek word μετά meta, meaning 'beyond' or 'after', and the Latin word materia, meaning 'matter' or 'material') is an engineered material whose properties arise not from the chemical composition of its base substances, but from their deliberately designed internal structure. These properties are often rare or absent in naturally occurring materials. Metamaterials are typically fashioned from multiple materials, such as metals and plastics, and arranged in repeating patterns at scales that are smaller than the wavelengths of the phenomena they influence. Their shape, geometry, size, orientation, and arrangement give them their properties of manipulating electromagnetic, acoustic, or seismic waves: by blocking, absorbing, enhancing, or bending waves, to achieve benefits that go beyond what is possible with conventional materials. Those that exhibit a negative index of refraction for particular wavelengths have been the focus of a substantial amount of research.

Potential applications of metamaterials are diverse and include sports equipment, optical filters, medical devices, remote aerospace applications, sensor detection and infrastructure monitoring, smart solar power management, lasers, crowd control, radomes, high-frequency battlefield communication and lenses for high-gain antennas, improving ultrasonic sensors, and even shielding structures from earthquakes. Metamaterials offer the potential to create super-lenses. A form of 'invisibility' was demonstrated using gradient-index materials. Acoustic and seismic metamaterials are also research areas.