Eventually some particularly egregious case, such as the beating of Rodney King in Los Angeles, causes a public outcry.

ECONOMIST: The police

Lemon reported for CNN's documentary Race and Rage: The Beating of Rodney King, which aired 20 years to the day of the beating.

CNN: About

As the executive director of an organization rocketed into existence 20 years ago because of a piece of media (the filming by a bystander of the beating of Rodney King by the Los Angeles police department), I firmly believe in the accelerating powers of visual media as applied to social progress.

FORBES: Up for Debate: How Personal Video Can Change the World

In more recent years, amateur video was credited with capturing the 1991 beating by Los Angeles police of Rodney King.

CNN: Neda: Latest iconic image to inspire

One was the video of the Rodney King beating, which took place during his second semester.

NEWYORKER: Greening the Ghetto

It was an unwelcome allegation for a department that overhauled itself after the notorious police beating in 1991 of a black man, Rodney King.

BBC: US women shot by LAPD in Dorner manhunt get $4m payout

He references Gates, the former chief of the department during the Rodney King beating case, and Fuhrman, a detective who called O.

CNN: SHARE THIS

In the document, which announced his planned rampage, Dorner said nothing had changed in the LAPD since its scandals of the 1990s, the Rodney King beating and the Rampart police corruption case.

CNN: STORY HIGHLIGHTS

The beating of Mr Denny was a long delayed reaction to another brutal beating, in March 1991, also caught on video-tape: that of a black motorist, Rodney King, by four white police officers.

ECONOMIST: Trouble in paradise