You totally don't understand.  No one is killing another person!  After careful evaluation, quite a process I might add, the terminally ill person is provided a script and they decide if they want to take it or just want to hold on to it.  Not even their families need to know.  It empowers the terminally ill, allows them to exit peacefully if they so choose, helps them decide when, perhaps surrounded by family and friends.  This is a person's personal choice.  Seriously, go read up.