The expectation that patients should comply with medical advice, and that they are being uncooperative and/or irrational if they do not, is based on a central assumption that the authority of medical practice derives from the objective and uniform application of scientific principles . This is the basis of medical efficacy and professional expertise . The early work on compliance was sensitive to the need for a highly competent and ethical medical practice in return for public acceptance of professional advice . Patients could only be expected to comply with treatment which was known to be effective, based on accurate diagnosis and to which they had given explicit and properly informed consent (Haynes & Sackett 1 979; Sackett & Haynes 1 976 ) . However, growing awareness of the extent to which professional practice deviated from these principles stimulated a powerful critique of medicine (see below) and, partly in response to this, the development throughout the 1 990s of Evidence-Based Medicine - once again spearheaded by Sackett and Haynes ( C ochrane 1 999; McAlister et a!. 2 000; Muir Gray 200 1 ; Sackett e t a!. 1 996; Sackett e t a!. 1 997 ) .