Sometimes video of officer-involved violence is damning to the officer, as with Derek Chauvin. Sometimes it makes the narrative more complicated, as with Kim Potter. And sometimes it comes to the officer's defense, which appears to be the case with this shooting in Columbus.

There's something perverse here. An officer shows up to a scene of a disturbance, and suddenly one girl is going after another with a knife.

If he just stands there and lets her get stabbed, that's not just unjust, it's a total dereliction of duty! And if he lets her get stabbed, it doesn't become a national news story where he becomes an instant national villain.

All we have right now is one body-cam clip. But based on what that shows and assuming nothing new and earthshaking, it seems like it's going to be really important for BLM activists to be clear-eyed and say loudly that this was a tragedy, but it's not "cop terror."