The easy part is the purchasing of equipment, such as body cameras and other technological devices, e.g., drones. The city of Seattle Police Department is pursuing the purchase of body cameras. As noted in this article, What Would New York Police Body Cameras Record? it is not that simple. Not only what will be recorded, but when will the cameras be turned on or off?

And as noted in this illustration, cameras don't show everything, Police Body Cameras: What Do You See? These video sequences show it is not that easy for the camera to be totally objective as to what happened.

Then there is this To the Point Podcast about dash cams and body cams. It examines the issue from a police perspective, civil rights perspective and freedom of information point of view. 

In summary, this is only one technology. As we move forward into this century there will be a "sorting out" of how and when various technologies can be used and under what circumstances. I expect court cases to be the final arbiter in the long term.