Predominately white trade union Solidarity is taking South Africa’s government to court, alleging racial discrimination in the police force.
It says the police service prefers to leave posts vacant rather than fill them with competent white officers, hindering the fight against crime.
After the end of white minority rule, affirmative action was introduced to help black people get jobs.
South Africa has one of the highest violent crime rates in the world.
The police service is currently under the spotlight after an officer shot dead a three-year-old boy.
The government has defended its “shoot-to-kill” policy, saying it will reduce crime.
It has not commented on the case brought by Solidarity.
Solidarity has filed nine cases against the South Africa Police Service (SAPS) and one against the prison service.