The doctor comes into your hospital room. You assume he is there to heal you, or at least to help ease your suffering if healing seems impossible. You view the doctor as an agent of life. But, if euthanasia becomes legal and more common, then when the doctor walks through the door you will not be sure that she is an agent of life. She might be the agent of death. Without your consent? Sure. Your money is running out; the insurance company does not want to continue payments; your children are distressed at your suffering and decide they can't take it anymore . . . The doctor agrees, and assures the family that the end will be painless; and, oh, don't tell the patient what is in the syringe, that would only cause mental anxiety and distress. The doctor enters: is he an agent of life or death? You don't know.

Some related thoughts from Cardinal George Pell.