I have been told that if you attempt suicide and fail, you are basically put on house arrest or you are institutionalized.
That being said, I agree when I hear people say suicide is one of the most selfish things you can do. Others may say, "Oh, the people are depressed. If they think it would be better if they were dead, it's their choice." It is their choice, but it's a stupid choice. A suicidal person may think that nobody loves them, their lives are going down the tubes, or nothing has ever gone right. But the reason I think that it's so selfish is that there has to have been one thing making your life worthwhile. One person whose life you have touched. Maybe your parents, siblings, friends, significant others. There's usually at least one thing that should keep someone from doing it. They decide that their reason for suicide is more important than those people who care for them.
Most suicides are due to "family problems." Death in the family, divorce, and all those reasons related to family. But the thing is that most of these problems don't usually end up with having no friends or having no one care about you. It's most likely that there is some one who still cares about you. It turns out that many suicides are spur of the moment. And these people with current problems don't usually think that some people's lives will be affected negatively. As it's been said, "Suicide is a permanent solution to a temporary problem."
So as for whether it should be legal, if some one attempts suicide or is having suicidal thoughts, they should be under watch to make sure they can't commit suicide. As for illness related, they should be treated in the best possible way. -frowns at fact that there aren't very effective depression treatments-
In short, (too late!) suicide should be taboo and shouldn't be tolerated. I apologize if I've sounded too harsh.