(a) The decision of a duly constituted agency of original jurisdiction on which an action was predicated will be final and binding upon all field offices of the Department of Veterans Affairs as to conclusions based on evidence on file at that time and will not be subject to revision on the same factual basis except by duly constituted appellate authorities or except as provided in § 21.4003. (See §§ 19.192 and 19.183 of this chapter.)

(b) Current determinations of line of duty, character of discharge, relationship, and other pertinent elements of eligibility for a program of education or special restorative training, made by either an adjudicative activity or an insurance activity by application of the same criteria and based on the same facts are binding one upon the other in the absence of clear and unmistakable error.