The Committee on Medical Rating of Physical Impairment PREFACE Evaluation or rating of permanent disability has long been recognized as an important and complex subject. In the past much confusion has resulted from inadequate understanding by physicians and others of (a) the scope of medical responsibility in evaluation of permanent disability; and (b) the difference between "permanent disability" and "permanent impairment." It is vitally important for every physician to be aware of his proper role in the evaluation of permanent disability under any private or public program for the disabled. It is equally important for him to have the necessary authoritative material to assist him in competently fulfilling his particular responsibility—the evaluation of permanent impariment. It is the purpose of this and other reports by the Committee on Medical Rating of Physical Impairment to correct a past confusion of terms and to provide a series of practical guides to the