The Chair of the Hearing Committee before which a case is pending (or the Chair of the Board on Professional Responsibility), if the matter is not before a Hearing Committee) may, upon request of respondent, authorize discovery from non-parties by deposition or by production and inspection of documents. Such requests must be made by written motion. Such motions shall be granted only if respondent demonstrates that respondent has a compelling need for the additional discovery in the preparation of respondent's defense and that such discovery will not be an undue burden on the complainant or other persons. Bar Counsel shall make available to respondent subpoenas to compel attendance of such witnesses and the production of such books, papers, and documents as may be necessary to implement discovery authorized under this Rule. Service of such subpoenas shall be arranged by respondent.