Complex issue.
When discussing this I think a distinction needs to be made over whether a person's situation is actually truly "hopeless", or whether he only perceives it that way.
In the latter case, those with clinical depression truly see no possibility for their problems, and the mental pain they have created, to be resolved. According to my ex, (who is in the head-shrinking business) this is typically associated with a change in the brain chemistry which at best can be treated with anti-depressants, counseling, and time, and at worst, is genetically based and may never go away completely.
These cases are the ones which are unfortunate if the patient chooses suicide, since there is treatment available to help most patients.
In the former case, where a person's situation is truly "hopeless", it may not always be so cut and dry.
Even "terminal" cancer cases have reversed and people survived. Great care must be taken to determine whether a situation is truly hopeless, and life not worth carrying on.
Is a person justified in taking their own life, once they determine it is truly hopeless?
That depends on the person. If there is no possibility for quality of life in their future, their life is an on-going hell, and absolutely no hope for improvement, then that person's conscience is the determining factor.
trask