As a widely recognised feature of work activity, procedural violations have been of considerable interest to human factors specialists, and several models have been proposed to aid in understanding their occurrence. A common feature of these models is that they depict violations as being, to a greater or lesser extent, intentional; therefore, rule-related behaviour could be reconceptualised as an exercise in decision-making. In this paper, we examine anaesthetists' use of rules from the perspective of naturalistic decision-making. Doing so suggests that their rule-related behaviour is a product of the extent to which following a rule is consistent with other principles that guide their decision-making. Observational and interview data from 23 consultant anaesthetists indicated the presence of three such principles: "doing the right thing"; "doing what works in the circumstances"; and "using one's skills and expertise". Hence, rule-related behaviour in this setting is better understood as a form of situated action than as the following or breaking of rules per se. We discuss the implications of this view for understanding why violations occur, and how to address them. © 2014 Springer-Verlag London.