The Administration, in its discretion, may call upon any practitioner for a full statement of the nature and extent of his interest in the subject matter presented by him before the Administration. Attorneys retained on a contingent fee basis shall file with the Administration a copy of the contract of employment. [G.O. 41, 3d Rev., 29 FR 14475, Oct. 22, 1964; 29 FR 15374, Nov. 17, 1964, as amended at 60 FR 38735, July 28, 1995]