20 C.F.R. § 200.10
(a) Power of attorney. An applicant or a beneficiary shall not be required to hire, retain or utilize the services of an attorney, agent, or other representative in any claim filed with the Board. In the event an applicant or beneficiary desires to be represented by another person, he or she shall file with the Board prior to the time of such representation a power of attorney signed by such applicant or beneficiary and naming such other person as the person authorized to represent the applicant or beneficiary with respect to matters in connection with his or her claim. However, the Board may recognize one of the following persons as the duly authorized representative of the applicant or beneficiary without requiring such power of attorney when it appears that such recognition is in the interest of the applicant or beneficiary:
[54 FR 43057, Oct. 20, 1989]