In the twentieth century a distinction has been made between forms of utilitarianism in which the rightness or wrongness of actions is a matter of the consequences of each particular action, case by case, and forms of utilitarianism in which the rightness or wrongness of actions is a matter of whether they are in accord with or in violation of a rule, with the rule justified by the consequences of its acceptance or general practice in the society. Richard Brandt, in his book Ethical Theory, published in 1959, introduced the terms “act-utilitarianism” and “rule-utilitarianism” to mark the distinction. These terms have since come to be used generically to cover a family of alternative theories.

Perhaps the most important division in types of rule-utilitarian theories is between “utilitarian generalization” and a “moral code” rule-utilitarianism, based on recognized rules enforced by sanctions. Utilitarian generalization starts with the particular case and generates rules by asking, “What would happen if everyone did the same?” requiring that an agent act in accord with what would have best consequences as a general practice rather than what would have best consequences in the individual case. Moral code theories can be divided into those that take only existing moral codes into account and those that propose that one act in accordance with an ideal moral code.