I think the question is fantastically complicated on a moral level....& I don't mean religion.
It's part of a bigger issue which Mestizo has touched on by mentioning abortion which most
rational people do accept, any worthwhile conclusion/answer has to consider the abortion aspect it's certainty not a different subject/thread ..at the end of the day it's still taking a human life, a perfectly healthy human life in most cases.
What about cases were people are just tired of living, there is big culture of this in northern Europe & a special/private clinic setup to accommodate anyone who can pay for it.
There is debate raging at the moment because it's been suggested its immoral to not abort down syndrome babies.
The reason it's illegal has nothing to do with religion, I listened to a debate recently between a bunch of doctors and religion wasn't even mentioned amongst the issues.
What are the implications for families green lighting suicides so they can inherit or hospitals taking decisions where a patient has no family or more importantly medical insurance.
What if Robin Williams or another depressed person asks for assisted suicide & the given reason is being tired of the pain, fighting depression and wants to die in peace?