The standard of care and expert evidence of accepted practice in medical negligence

The topic of this article is the perennial issue in medical negligence litigation of various kinds of the extent to which it is a defence to a charge of lack of reasonable care that the defendant's conduct complied with accepted professional practice. Recent English interpretations of the controversial Bolam principle are considered, before the current approach of the courts and the Health and Disability Commissioner in New Zealand is described, using case illustrations. In New Zealand expert medical opinion of accepted practice is relevant to, but not conclusive of, the standard of care. There is, however, more freedom than pursuant to the current English approach for a decision-maker to reject expert opinion of accepted practice, because he or she is able to examine not just the logical defensibility of the practice but its overall reasonableness, including where the practice involved a risk assessment on a matter of clinical judgment. A decision to reject expert opinion of accepted practice is more readily made in areas which do not involve assessment, diagnosis and treatment.