Blacks make up about 67 per cent of Ferguson's population, but 88 per cent of documented uses of force by Ferguson police from 2010 to 2014 were against African Americans. In all cases of police dog use and bites, the person was black. In traffic violation stops, 85 per cent of people stopped, 90 per cent of those who received a ticket and 93 per cent of people arrested were black.
Holder, who is African-American, first explained his department's decision not to bring civil rights charges against Darren Wilson, the officer who shot dead 18-year-old Michael Brown during a confrontation in Ferguson last year. A local grand jury had already decided not to indict Wilson for his actions.
"Michael Brown's death, though a tragedy, did not involve prosecutable conduct on the part of Officer Wilson," Holder said. "This outcome is supported by the facts we have found - but I also know these findings may not be consistent with some people's expectations."
He then addressed a broader investigation into the behaviour of the Ferguson police department, an all-white force in an overwhelmingly African-American area.
"This was a community where local authorities consistently approached law enforcement not as a means for protecting public safety, but as a way to generate revenue," he said.
"A community where both policing and municipal court practices were found to disproportionately harm African American residents [and] created an intensely charged atmosphere where people feel under assault and under siege by those charged to serve and protect them."
Holder said investigators uncovered huge pressure on police to deliver fines to provide revenue to fill municipal demands. He said that there was an unofficial competition between some officers for who could issue the highest number of citations for a single stop, with the record standing at 14.
Crass culture - shocking racist emails and jokes revealed
• A November 2008 email said President Barack Obama won't be president for long because "what black man holds a steady job for four years"?
• An April 2011 email depicted President Obama as a chimpanzee
• A May 2011 email said: "An African-American woman in New Orleans was admitted into the hospital for a pregnancy termination. Two weeks later she received a cheque for $5000. She phoned the hospital to ask who it was from. The hospital said, 'Crimestoppers'."
• A June 2011 email said a man wanted to obtain "welfare" for his dogs because they "have no frigging clue who their daddies are".
• An October 2011 email had a photo of a bare-chested group of dancing women, apparently in Africa, with the caption, "Michelle Obama's High School Reunion".
Ferguson findings
• African-Americans represented 67 per cent of the population in Ferguson, but represented 85 per cent of the people subject to a vehicle stop and 93 per cent of the people arrested from 2012-2014.
• African-American drivers in Ferguson are more than twice as likely to be searched during vehicle stops, but are found in possession of contraband 26 per cent less often than white drivers.
• In 88 per cent of the cases in which the Ferguson Police Department used force, it was against African-Americans. In all of the 14 dog-bite incidents for which racial information was available, the person bitten was African-American.
• In Ferguson court cases, African-Americans are 68 per cent less likely than others to have their cases dismissed by a municipal judge.
• From April to September 2014, 95 per cent of people held longer than two days in the Ferguson jail were black. The Police Department also overwhelmingly charges African-Americans with certain petty offences.
- Washington Post-Bloomberg
