The city I live in recently voted to continue the practice of "poisoning the water hole."

I even decided to report this crime to the police, but chose not to after discussing it with various others.

It is a crime, though: either, it's "practicing medicine without a licence" if this substance is helpful; or, it's "poisoning the populace with neurotoxins" if it isn't.

Either way, there is one person (or a group of people) who are performing this action, and they can be stopped, one way or another. I don't like the idea of putting people in cages, but it seems like a proper solution to this particular crime: sequester them from others until they admit to wrongdoing, and agree to stop doing it.