Alison Saunders, chief prosecutor for CPS London, said she had advised the Independent Police Complaints Commission to charge PC MacFarlane despite the CPS's decision not to charge him in January.
In March, the complainant's lawyers challenged that decision and, in accordance with standard CPS practice, Grace Ononiwu, Deputy Chief Crown Prosecutor for CPS London, directed that the case be reviewed by a more senior lawyer who was not previously involved.
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.
More top news
Extra armed police will guard major sporting events in London this weekend after the military was drafted in to protect key locations.
Damon Smith, 20, has been jailed at the Old Bailey for 15 years for planting a home-made bomb on a busy Tube train.
The South East has been basking in sunshine and clear skies for the last few days but it won't last.