The claim is sometimes made that it is impossible for black people to be racist, because racism is an exercise of power, and white people have all the power.
This is nonsense, and obviously so. Of course it is possible for a black person to assault a white person for no reason other than his race. Racial bigotry does not have to be complicated.
The specific claim that racism is always an exercise of power is as wrong as the claim that rape is about power (instead of sexual pleasure and the evolutionary imperative towards reproduction). Racism can be simple bigotry.
The specific claim that white people have all the power in a nebulous "structural" way is false. Power is not held by "white people" as a class. One white person can have less power than one black person.
The claim that only whites can be racist is really a rhetorical technique to get white people to shut up and accept racism against them, whether it be personal bigotry and violence, or a political attempt to take money and property from white people as a class, or "positive discrimination" and "affirmative action" against white people.
Publicly identifying it as purely a rhetorical technique and not a serious idea robs it of some of its power.