James Fieser, Professor of Philosophy at the University of Tennessee at Martin, in a Sep. 1, 2017 version of the manuscript, "Moral Issues that Divide Us," available via his faculty profile at utm.edu, stated:

“Another distinction is between voluntary and non-voluntary euthanasia. Voluntary euthanasia is when a competent adult requests or gives informed consent to a particular death-causing action. This is the scenario that we have so far been presuming with Bob’s case: he is conscious, rational, and in a proper mental state by which he can make a willful request. Often, though, people do not have the mental competence to make these decisions, such as when they are unconscious, delirious, or demented. In these situations an act of euthanasia would be nonvoluntary when the decision is made by a third party, and not the person himself who is to die. For example, if Bob fell into a coma, Bob’s wife might have made the decision to terminate his life. It is important to note, though, that the term ‘nonvoluntary’ does not mean the same thing as ‘involuntary.’ An involuntary act is one which is imposed on a person against his will, such as if Bob did not want to die and his physician gave him a lethal injection anyway. This would be a case of murder, and not mercy killing. Rather, with nonvoluntary euthanasia, a patient is incompetent to make a decision, and a third-party steps in as a surrogate to make the call on behalf of the patient’s best interests.”

Sep. 1, 2017