The blacks who get shot by White policemen get all the media attention, and they try to make it solely a racial thing, but there's a lot of YouTube videos of cops also needlessly brutalizing and shooting Whites. There are YouTube videos of cops pulling people over on the highway and stealing money from their car, so-called "asset forfeiture."
There's two different issues at play: the alleged brutality of white cops against blacks purely for racial reasons, which happens very rarely if at all anymore; and the militarization of cops in equipment and tactics, which is class-based more than race-based. That's why people like Paul Craig Roberts (wrongfully) sided with Michael Brown, because they've become so anti-police in general.
But the systemic problem is race-based at its heart, because multiculturalism is an artificial, alien construct that can only be enforced by the barrel of a gun, i.e., a police state.