Good evening Greynatter,
I agree with what has been suggested in case this complex matter may well turn on the grounds of “mental health”.
Two things come to mind:
- In your shoes I would seek to document any and all instances you witnessed or heard of that demonstrated that the neighbour is not ALWAYS “irrational” and not ALWAYS suffering from “mental health issues”, but indeed AT TIMES is quite “rational” and functions well. If you can show situations that paint a picture of a person behaving at times in a manner that is “normal and reasonable” and at other times behaving as though he is “unwell”, that may help dilute the presumption of genuine suffering from “mentally illness” and may rob him of the ability to diminish his liability (assuming he is found liable); and
- Look up “private nuisance”. Nuisance (private or public) is a civil wrong that involves a person or persons causing indirect, unwarranted and/or unreasonable interference with the interests of others. Google strata lawyers (who sponsor this website) for articles on the subject and hunt down previous cases at tribunals and courts to see the outcomes of those cases.
Good luck!