Disability determination in the US is traditionally based on the classical medical diease-illness paradigm: if one defines the quantity of disease (pathoanatomical abnormality), one can predict the magnitude of illness (symptoms), including how the illness will operate in the workplace. This inference underlies the Handbook of Social Security Disability Insurance (SSDI) and the early attempts at “schedules” in workers' compensation. The reliability and validity of this inference, however, leave much to be desired. The alternatives currently used include the “expert opinion,” even when based on direct examination, which is heavily used in both programs. The opinion of the worker's personal physician is relied upon only before the administrative law judge in the SSDI program. These administrative alternatives color the doctor-patient relationship and the worker's perceptions of his illness.