"...I'd...require on-duty law enforcement to wear some sort of video recording equipment to record in a loop the last 30 minutes..."
I say "not enough". There should be no way for the officer to disable the camera. If the camera is not recording, the officer does not work that day.
Also, there needs to be a real-time data uplink.
Also, at least an entire shift of recording time. If the cop makes comments beforehand I want to know about it, like the cop in Arizona who stated hours before shooting a homeless guy that he planned on "shooting him in the penis". (he then murdered the guy).