Unless you have hard evidence that they're going to hurt someone, the authorities won't get involved. Yet, families and friends often know when someone is "off." What steps would you or could you take to prevent something bad from happening?
If the threat is from, say, a thoroughly and chronically incompetent senior surgeon in a major, well-respected hospital, then I think there may still be a tendency to foot-dragging with the prevailing culture of not rocking the boat. I have been in the shuttle-booster ‘O’ ring – medical malpractice kind of arena myself and it never looks so clear-cut from the inside as the newspapers make it seem.
Even when police are aware a dangerous lunatic, serial killer, serial rapist is because of some failing of the legal system back on the street, in some places, in some situations, the legal protections in place often favor the criminal to the detriment of public safety – as we well know.
But danger on a massively larger scale is still beset by prevarication, machination and evasion tactics - land harboring dangerous levels of asbestos, pesticides, arsenic, heavy metals or various kinds, and other toxic pollutants, and cases like Erin Brokovitch, the Flint and Wiarton water supply, the $448 million cleanup of the Great Slave Lake toxic disaster, etc. awful and dangerous as they are, have nevertheless still been met with resistance, endless discussion, excuses and threats, before there had been any real movement towards remedial action.
‘Safety of the public’ is not so much an actual concern and reason for decisive action, as a phrase on a TV newsreader's prompter screen.