It would seem clear that police body cameras serve the common good, protecting the police from false complaints, providing evidence of malfeasance, and putting a break on the human impulse to behave badly. And some data from San Diego supports this intuition.
Use of body cameras in Missouri has stalled, not because the benefits are doubted but because of cost and because of privacy concerns. For example, during a domestic dispute call, if one of the parties asks the police to turn the cameras off, should they? And is the video of a family quarrel subject to sunshine laws?
But an interactive article in the New York Times illustrates the ambiguity in many film clips. The point of view belongs to the police officer; so does the commentary. It isn't always easy to tell what's happening.
I think cameras are a useful tool, but they won't solve the problems of police bias and citizen mistrust.