As an example of involuntary euthanasia, the cardinal cited reports from the Netherlands in which "a doctor surreptitiously euthanized a nun over her objections, and justified it on the grounds that she was mistaken about her best interests due to an irrational and superstitious commitment to religious belief."
In U.S. states where euthanasia has been legalized, there have been cases of insurance companies that offer to pay for assisted suicide drugs rather than pay for costly medical treatment. Family members have also pressured patients into choosing suicide.
The cardinal distinguished assisted suicide and euthanasia from aggressive pain treatment, which aims to eliminate suffering through potentially risky means, not to kill the patient.
He said assisted suicide or direct killing are deceptively described as "aid in dying." This is "a fabricated expression whose only rhetorical function is to conceal the very nature of the death-dealing action it describes."
"The use of euphemism or obscure terminology in issues involving life and death should always alert us to an effort to hide the truth," Cardinal Mueller said.
He countered justification for assisted suicide that claims that euthanasia only affects the patient and people are entitled to choose the time and manner of their death.
"Anyone who has ever experienced the suicide of a loved one or even a casual acquaintance knows the profound effects this can have on entire communities," he said, citing the demonstrated risks of suicide spreading like a "contagion."
Euthanasia is not self-contained, as it affects families and communities and alters the medical community's relationship to patients and the public.
Suicidal patients are often not in a position to exercise autonomy, and suicidal desires often depart once mental illness and pain are effectively treated.
"This is true even among the terminally ill," he said.
The cardinal defended doctors and nurses who could face coercion for refusing to participate in euthanasia.
" No one who trains and takes an oath to care for the sick should be pressed into ending the lives of the very people that they have promised to serve," he said, saying that refusal to aid in euthanasia "represents basic fidelity to the very medical art that the physician professes."
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Cardinal Mueller said church teaching on euthanasia is accessible and enduring.
"The Catholic Church has long recognized that every human being, no matter his or her condition or circumstance, is possessed of inalienable and equal dignity," he said. "This beautiful truth about the human person and his matchless worth is intelligible and self evident to every person of good will, regardless of faith tradition."
The cardinal cited the Congregation for the Doctrine of the Faith's 1980 Declaration on Euthanasia, which said that making an attempt on the life of an innocent person opposes God's love for the person.
While there are psychological factors that diminish or remove moral responsibility, to take one's own life is "often a refusal of love for self, the denial of a natural instinct to live, a flight from the duties of justice and charity owed to one's neighbor, to various communities or to the whole of society."