Pretty much every state has their own, state-level investigation bureau [0]. Automatically transferring footage to an internal affairs department there would distance it from the actual department, while preserving state control.

Aside from activating / deactivating the camera (with clear guidelines and penalties for doing / not doing so), and connecting it to a network at the end of a shift, it should be a black box. None of the IT functions should run out of the same police force.

Consequently, this also protects officers in the case of equipment failure: timestamp the activation / deactivation signals in a separate log file. If the footage isn't there, but they activated, then it's no longer their reputation on the line, because they had no involvement in the chain of custody.

[0] https://en.wikipedia.org/wiki/State_bureau_of_investigation

Yeah, a state department side-steps a lot of those problems (but also possibly lets states ignore it). A federal law requiring police interactions to be recorded and submitted to a state entity and requiring it be stored for a certain period would probably suffice. Then the FBI or whoever investigated an issue Federally (if it got to that) could subpoena it, since it's supposed to exist, and be handled by the state.

I agree it should be a black box. Rule #1 for accountability is that you don't rely on the entity that's being examined to give absolutely correct info. Whether that's debugging a process or reviewing an organization, outside instrumentation is essential.