Police riot

A police riot is a confrontation between police (or similar military or security force) and civilians. The term can also describe a riot by civilians caused or instigated by police (e.g. an agent provocateur). In such situations, views of civilians and police officers often differ widely as to the legitimacy of the police violence and the term "police riot" is not generally used by public officials, as it strongly implies government culpability. In extreme situations, police riots have been known to trigger reprisal violence and the breakdown of public order, such as during the Soweto Uprising in South Africa and the 1992 Los Angeles Riots. Recently the term has been applied to events such as the Seattle W.T.O. protests, where police clad in riot gear used clubs, tear gas and projectiles to disperse groups of protesters, anarchists and direct action anti-capitalists.

Haymarket Riot
During the early years of labor union organizing, police violence was frequently used in efforts to quell protesting workers. One notable incident took place in May 1884, when police killed four striking workers at the McCormick Harvesting Machine Co. in Chicago. The following day, a peaceful demonstration in Haymarket Square erupted in violence when a bomb was thrown, killing eight policemen — an event known as the Haymarket Riot. Fifty years later, in July 1934, police in San Francisco were involved in several encounters with striking longshore workers. After two picketers were killed, the other area unions joined together and called a general strike of all workers (the "Big Strike"). Subsequent criticism of the police was probably the occasion for the coining of the term "police riot."

Vietnam War protests
During the Vietnam War, anti-war demonstrators frequently clashed with police, who were equipped with billy clubs and tear gas. The demonstrators claimed that the attacks were unprovoked; the authorities claimed the demonstrators were rioting. The most notorious of these assaults, which was shown on television and which included national television reporters in the mayhem, took place during the August 1968 Democratic National Convention in Chicago, which was the scene of massive anti-war street protests. The actions of the police were later described as a police riot by the Walker Report to the US National Commission on the Causes and Prevention of Violence.

Tompkins Square Park police riot
In August 1988, a riot erupted in Tompkins Square Park in the Lower East Side New York when police, some mounted on horseback, attempted to enforce a newly passed curfew for the park. Bystanders, artists, residents, homeless people, reporters, and political activists were caught up in the police action that took place during the night of August 6–7. Videotape evidence, provided by onlookers and participants, showed seemingly-unprovoked violent acts by the police, as well as a number of officers having covered up or removed their names and badge numbers from their uniforms. The footage was broadcast on local television, resulting in widespread public awareness. In an editorial The New York Times dubbed the incident a "police riot." The incident became known as the Tompkins Square Park Police Riot.

Battle of the Beanfield
During an attempt to enforce an exclusion zone around Stonehenge, Wiltshire, in 1985, the police entered the field where a group of travellers known as the Peace Convoy were being detained and began smashing the vehicles and beating the occupants. The travellers eventually sued the Wiltshire police force for wrongful arrest, assault and criminal damage.