The cops will do everything they can to ruin you. If you dare try to defend yourself, you are done. If you try to defend someone else, you’re even more screwed.
I had a buddy, passed on some years ago who told flat out told me “The police are not there to protect you. They’re armed agents of the state and that is who they protect’’ He said “Learn to protect yourself. Get a gun’’.
On that point I’m trying. In NJ it’s tough.