I've no idea how you go about obtaining proof in those circumstances.
I have dealt with suicidal ideation my entire adult life. It's a symptom of a co-morbid depression. I've also been subject to stressors like most other people, I've been close to going ahead with ending my life on numerous occasions. How anyone could possibly determine what would be the cause of my suicide or the impetus behind it I have no idea, because that's something that only I am ever privy to, but not only that, with the SI being a symptom there often isn't any causal factor at all, it's just something my mind does.
So all of that being the case, how does one "prove" that any of the various stressors in my life are the causal factor in my suicide?
Even if I left a note explaining precisely why I've ended my life, that's a simple matter to pick apart, because
- I've committed suicide, not the actions of anyone who can be said to be sound of mind and in a rational place
- There is nothing preventing me from concocting any reason I like for my suicide, including maliciously implicating something or someone entirely innocent simply because I feel like it, or, given I am not in a normal state of mind in the first place, I misguidedly apportion my suicide to something which is perfectly reasonable because my interpretation of it or reaction to it is unreasonable
You can not rationalise irrational behaviour, and you can not open up someone's head and examine the thoughts going on inside, especially not once they are deceased and no longer able to articulate themselves.
I agree with the notion in principle, because I believe it's a noble thought, but I can not see how this could possibly result in any sort of worthwhile or workable law.