Should a person be allowed to take his or her life with a doctor's help when it is no longer considered worth living? Three states permit it, and the issue has come to Vermont. Encouraged by the election of Gov. Peter Shumlin, who supports it, ?death with dignity'' advocates have introduced a bill that would make Vermont the fourth state to allow doctors to prescribe some terminally ill patients a lethal dose of drugs they could use to end their lives. It would allow doctors to prescribe for patients, who had requested it three times -- once in writing -- a lethal dose of pills that the patient would then administer to himself or herself. Supporters say the measure would give patients a sense of control over a time of their lives that for too many is lost to the machinery and personnel of modern medicine. Opponents say it could put society on a slippery slope toward euthanasia.