Kathleen, the criteria noted in this article for the California law are that the patient have a terminal disease, is likely to die within 6 months, is of sound mind and can self administer the drug.  Doesn't sound like an execution carried out for anyone's convenience to me.  I think that for someone dying from a terminal illness, having the option of taking control of the time and circumstances of death would be a comfort whether they ended up exercising that option or not.