JOHANNESBURG — After thieves broke into her car, a white South African motorist lashed out at the responding black police officers. She called black people “plain and simple useless” before unleashing the most offensive racial slur around.

Not the N-word, but the K-word: kaffir.

The word is South Africa’s most charged epithet, a term historically used by whites to denigrate black people and considered so offensive that it is rarely said out loud or rendered fully in print.

Now because of her racist tirade, caught on video early this year, the driver of the car, Vicki Momberg, is on trial and will probably face a hefty fine. Because of her rant and several others like it, lawmakers in South Africa, where the wounds of apartheid remain raw, are moving to make hate speech a crime punishable by up to 10 years in prison.

This week, South Africa released a draft law that would criminalize racism by referring future hate speech cases to criminal courts instead of the civil courts where they are currently heard.