I don't think you can know that until they start causing safety problems, right? If you develop a heuristic like overdose = harms other patients, then you are executing people who did nothing wrong except make one little mistake with some chemicals. You then get second order effects to further discriminate, "this guy is white and he's unconscious in a rich neighborhood" versus "this guy is black and he's unconscious in a poor neighborhood", and eventually it all starts to feel a little evil.

As a human race, we're supposed to be helping each other a little bit. It's how we're wired.