In this paper we examine the way disjunctive choices work in conversational context. We focus on disjunctive deontic rules, such as "you must either submit an essay or attend an exam". According to the Gricean "maxim of orderliness", a derivative of the "maxim of manner", people should interpret the first-mentioned option as the one preferred by the speaker. Two experiments demonstrated order bias, a non-logical preference for the first-mentioned option in the disjunctive situations of obligatory choice and free choice permissions, but not in the non-disjunctive situation of obligatory consequences. Order bias influences interpretations of the speaker's preferences, but not of the recipient's preferences; it was mainly a function of the nature of the situation, while linguistic form had only limited effect. We offer a general theoretical framework for order bias as a communicative device, constraining both interpretation and generation of utterances. (Contains 9 footnotes and 6 tables.)