The following Fact Sheet has been prepared by the South Australian Voluntary Euthanasia Society (SAVES). For further information visit their website at

South Australian Voluntary Euthanasia Society

SAVES Fact Sheet No.23

The Principle of Double Effect


The ethical principle of Double Effect is used to justify medical treatment designed to relieve suffering where death is its unintended (though foreseen) consequence. It comes from "the rule of double effect" developed by Roman Catholic moral theologians in the Middle Ages as a response to situations requiring actions in which it is impossible to avoid all harmful consequences. The rule makes intention in the mind of the doctor a crucial factor in judging the moral correctness of the doctor's action because of the Roman Catholic teaching that it is never permissible to "intend" the death of an "innocent person". An innocent person is one who has not forfeited the right to life by the way he or she behaves, eg, by threatening or taking the lives of others.

The rule applies if:


Under the rule, administering medication in dosages likely to cause death in order to relieve a terminally ill patient's suffering is morally correct, provided the above four conditions are met.


There are many who regard the rule of double effect as seriously flawed. Grounds for its rejection include:


  • the patient's right of self-determination and bodily integrity;

  • the provision of informed consent;

  • the absence of less harmful alternatives acceptable to the patient and

  • the severity of the patient's suffering

    as the factors which should determine the moral and legal validity of the doctor's actions rather than whether or not the doctor "intended" the patient to die.


Further reading, including 42 references, is contained in the New England Journal of Medicine of 11 December 1997 (Quill TE, Dresser JD, Brock DW. The Rule of Double Effect - A Critique of Its Role in End-of-Life Decision Making. N Engl J Med 1997; 337: 1768-71). See also Correspondence, N Engl J Med 1998; 338:1389-90.

Further information contact SAVES at:

Or contact: Hon Secretary, SAVES, PO Box 2151, Kent Town, SA 5071, Australia - Fax + 61 8 8265 2287