Patient safety has become a health policy priority around the world. Acknowledging that 'to err is human' has led to attempts to design systems and rules that limit the capacity for individual discretion and thereby reduce clinical errors. In addition, great emphasis is being placed on the need to eradicate cultures of blame, which are assumed to discourage clinicians from reporting errors, and to establish a 'safety culture', which encourages openness and honesty. These efforts are underpinned by cognitive psychological explanations of the way individuals process information, which leads them to make errors of judgement. This paper examines the attitudes of hospital doctors and managers to the implementation of rules in the context of patient safety. Our analysis, using interpretive research focused on narrative identity, provides an alternative perspective to that offered by the current safety orthodoxy. This leads us to suggest that the achievement of a 'safety culture' is a remote prospect. The failure to follow formal written rules relates not to a deficiency in the cognitive capacity of individuals acting in isolation, but to the identities which individuals occupy, create and negotiate and the social rules (as opposed to clinical guidelines or protocols) which correspond to those identities.