Should the severe mentally ill be allowed to marry and have children?

As far as i can tell! Yes! Any mentally ill people must be checked if they couldn't handle themselves, they shouldn't be allowed to marry nor have children cause it has no benefit but all damage to another human being and the whole society in long term.

Interesting question, especially as phrased.

I have never given it serious consideration but the following comes to mind.

What is a "severe" mental illness---what about a high functioning schizophrenic vs a low functioning ADHD person.

When is a non-symptomatic mentally ill person actually deemed to be mentally ill---(a retrospective diagnosis would be potentially problematic.)

And is marriage a question or status or contract?.  (Read this pdf if you are so inclined to delve deeper)

http://www.law.harvard.edu/faculty/jhalley/cv/1-behind_the_law_of_marriage.2.15.11.pdf

And how many difficulties "should" you bring into a marriage? (Think "helmet law.")