AbstractCentral elements of Roman Catholic treatment ethics include: 1) that rejection of treatment with the intent of hastening death (even for a good end) is ethically equivalent to active euthanasia with the same intent; 2) a distinction between morally obligatory “ordinary” treatment and morally optional “extraordinary treatment”; 3) that the quality of the patient’s life is not be a legitimate basis for rejecting treatment; and 4) that extraordinary treatment is not forbidden, but optional, and that it is the patient or the patient’s legal surrogate–not the doctor– who has the right to choose or reject it. Despite these principles, even in a cultural climate fully sympathetic to Catholic treatment ethics, it is appropriate as a legal matter to maintain the doctrine of informed consent under which it is possible for patients or their surrogates to reject life-preserving treatment, including for unethical reasons. It is normally impossible to enforce in practice in the external forum a differentiation between rejection of treatment for ethically acceptable and ethically unacceptable reasons. By contrast, in cases of direct killing, such as assisting suicide, the intent to cause death is unmistakable (as opposed to accepting an increased risk of death as a foreseeable but unintended consequence of pursuing a good end). In a pluralistic society Catholic ethics cannot be legislatively enforced on the ground that they are compelled by Catholic teaching. However, the basic principles of Catholic treatment ethics may be justified based on logic and widely accepted norms of human equality independently of revelation or ecclesiastical authority. Particularly in protecting the right of individuals to choose and obtain life-saving medical treatment regardless of their “quality of life,” and in suicide prevention, secular law can and should be congruent with key aspects of Catholic health care ethics.