Errors in medicine are a major cause of harm to patients. Though there is little controversy among clinicians about the importance of accurate and reliable clinical data and the imperative of correct diagnosis, that commitment to exactitude dissolves when errors happen. Then, clinicians and managers may behave in a way that limits investigation. We often use the subjectivity and complexity of medicine to rationalise and justify error.

Many factors explain this reluctance to investigate and to accept error. If we are to design effective systems to prevent errors from affecting patients, we must understand these factors. The following case study illustrates the concerns, fears, and practical problems that we faced in conducting an evaluation of misinterpreted prostate biopsies.