Michale: Several years ago I had this conversation w/Chief Kerns.  I was, and still am, very supportive of "body-cams".  They are an "unbiased" record of the incident and can provide a level of accountability which should as you say, benefit everyone.  However, they MUST be immediately operating whenever an officer "starts" into an interaction.  Their use is still contentious with some police departments very hesitant to adopt their use.  

Just think how different things might have been or will be if the officers who recently shot Mr. Rodriguez had been wearing those body-cams.   regards,  Gary