A Scotland Yard officer accused of racially abusing a suspect will be charged after a U-turn by prosecutors.
Both the alleged victim and Britain's top police officer welcomed the Crown Prosecution Service's decision to take Pc Alex MacFarlane to court.
Reviewing lawyers watched footage appearing to show the officer say to 21-year-old Mauro Demetrio: "The problem with you is you will always be a n*****, yeah?"
Alison Saunders, chief prosecutor for London, said the original CPS decision was "regrettable", adding that a prosecution was necessary to maintain public confidence.
Mr Demetrio said he was "relieved that some action is now being taken" before adding: "I hope now to see justice."
The charging decision hinged on mobile phone footage, allegedly taken by Mr Demetrio, from Beckton, east London, in the wake of the riots last August.
Mr Demetrio was held on suspicion of drug-driving but no action was taken.
The CPS announcement came after the police watchdog announced a review of a string of complaints about racism at the Metropolitan Police, warning of the risks of "much wider disaffection and dissatisfaction" with the force.
Commissioner Bernard Hogan-Howe said he was pleased that prosecutors had reviewed their original decision.
Giving evidence to the Commons Home Affairs Select Committee, Mr Hogan-Howe also stressed that at the moment the claims were only allegations.
"We have to let the criminal case take its course," he said.
"I'm glad that it will be tested in court."
Ms Saunders said she had advised the Independent Police Complaints Commission to charge Pc MacFarlane with a public order offence after the review.
"That review is now complete and the conclusion, based on all the evidence now available, is that there is sufficient evidence for a realistic prospect of conviction to charge Pc MacFarlane with a racially aggravated public order offence contrary to Section 4a of the Public Order Act 1986 and Section 31 of the Crime and Disorder Act 1998," she said.
"When a review shows a previous decision not to prosecute is wrong, it is open to the CPS to rectify that error by bringing new proceedings."
Ms Saunders said she had taken the decision that "as well as there being sufficient evidence for a realistic prospect of conviction, and a prosecution being in the public interest, a prosecution is necessary in order to maintain confidence in the criminal justice system."
She added: "That is the test I must apply under the Code for Crown Prosecutors when reinstituting a prosecution.
"Accordingly, I have advised the Independent Police Complaints Commission to charge Pc MacFarlane.
"It is regrettable that the original decision was wrong, but I hope the action taken and my decision today demonstrates the willingness of the CPS to review its decisions independently and swiftly and to take appropriate action where necessary."
An additional charge of assault relating to an allegation of "strangulation" will not be pursued, the CPS said.
Ms Saunders added: "However, having now had opportunity to consider all available evidence, including the statements of others in the van alongside the recording, the lawyer reviewing the case concluded that the inconsistencies in the various accounts of what happened were such that no additional charge could properly be added.
"The inconsistencies included a dispute over the identity of the officer who took hold of the complainant - the complainant said that this was one officer but all other witnesses dispute this."
Another allegation of abuse by a police officer against a youth at Forest Gate police station remains under consideration, the CPS said.
There are now 11 separate allegations under investigation, involving 10 police officers.
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