Evidence-based medicine (EBM) puts forward a hierarchy of evidence for informing therapeutic decisions. An unambiguous interpretation of how to apply EBM's hierarchy has not been provided in the clinical literature. However, as much as an interpretation is provided proponents suggest a categorical interpretation. The categorical interpretation holds that all the results of randomised trials always trump evidence from lower down the hierarchy when it comes to informing therapeutic decisions. Most of the critical replies to EBM react to this interpretation. While (...) proponents of EBM can avoid some of the problems raised by critics by suitably limited the claims made on behalf of the hierarchy, further problems arise. If EBM is to inform therapeutic decisions then a considerably more restricted, and context dependent interpretation of EBM's hierarchy is needed. (shrink)