To answer your question, no i can’t think of authorities which use violence to assert themselves that meet those high standards. BUT, I certainly don’t think it’s impossible to imagine a policing body which could meet them. Even among violent authorities there’s a spectrum of the degree of corruption and dysfunction.
The problem is that power of any kind is inherently opposed to regulation, accountability, and transparency - so it necessarily has to be imposed from the outside. Police departments in the US are extreme examples of a model that effectively has none of these checks and balances.
