Theory that the principle of utility is (or ought to be) the source of rules of conduct, and that such rules determine whether particular acts are right or wrong. Rules justified by their general utilitarian consequences may nonetheless require actions that do not maximise utility in particular circumstances. The justification is that, despite such cases, overall utility is maximised by a rule-following system, compared to the alternative of having individuals decide on conduct in particular circumstances. Human beings have a notoriously difficult time being impartial about utility (or anything else) in matters involving their self-interest. Rules have the virtue of imposing a degree of "objectivity" by virtue of their inflexibility. Consistency requires that rules be applied in the same way to relevantly similar circumstances. Unfortunately, what is relevantly similar is not always clear. Contrast with act utilitarianism.