I don't want turn this into a religious debate, but this is what I'm thinking... (I'm not talking about people that can't decide for themselves). If you sign a paper that says that you are allowing doctors to kill you, isn't that technically suicide?? Or if you intentionally provoke a police officer to put a bullet in you (for whatever reason, you are terminally ill, or you're just tired of life) that is also a suicide. It doesn't matter who pulls the trigger or inserts the lethal amount of morphine, if you are willingly doing that it's suicide and it's a mortal sin (I'm talking about theists), I'm an agnostic btw, but I'm still not sure what I would decide.
I'm asking this nicely