The medical emergency team (MET), which may be summoned by anyone in a hospital to treat a patient who appears acutely unwell, has been generally accepted as scientifically rational, with no adverse clinical outcomes and only modest resource requirements. Despite this, many centres appear to be awaiting "gold standard" evidence of its effectiveness. We suggest that the quest for evidence is providing scientific justification for institutional inertia, and that further delay in implementing this system may even be unethical. We propose that decisions about changes in healthcare should consider scientific rationality, clinical reasonableness and resource implications, as well as evidence and ethical implications.