In theory, I like the idea of police all having body cameras. When something goes wrong, whether its a complaint that cops said something inappropriate or threatening or an alleged incident of police brutality, having video footage at least hypothetically could quickly shut down false accusations and make investigating the allegations more open-and-shut. But in practice, I have a few concerns.
First, if the cameras are always on, that's a lot of footage. Many state freedom of information acts would likely require police to release essentially any footage that was requested from the public. That's going to be a lot of additional FOIA requests for police departments to respond to. They'll have to look through the footage for anything that needs to be blurred out to protect privacy (addresses, children's faces, bystanders, license plates, etc). The man hours on that -- even if you outsource it to low-wage workers in developing countries -- is going to add up fast.
Second, is how the footage ends up being used. I can already see opportunists like Jesse Jackson and Al Sharpton requesting tons of footage, selectively editing it, and basically putting out hits on officers. We already saw this with the Rodney King riots. The admittedly brutal footage that was shown was edited by the media outlet that first received a copy. They took out the first few seconds where things originally escalated with King. The jury members who acquitted the officers later said that those early seconds were key to their decision. But the public had formed its own opinion -- based on footage edited down to arguably make it more incendiary -- on what happened, long before they got to hear that there was more to the story.
Third, and I think there are ways to address this, but I worry about the possibility that, particularly during the early adoption phase, officers will not always know when to turn on their body cameras. If an officer is walking the streets patrolling and something happens, what if there isn't time to smack the button and turn on the camera? And then when things go bad, it looks suspiciously self-serving that the camera wasn't on?