Sec. 31. (a) A master may issue a subpoena for:
(1) the attendance of witnesses;
(2) the production of documentary evidence; or
(3) discovery;
in a proceeding before the masters. The master shall serve the subpoena in the manner provided by law.
(b) The chairman of the commission may issue a subpoena for:
(1) the attendance of witnesses;
(2) the production of documentary evidence; or
(3) discovery;
in a proceeding before the commission in which masters have not been appointed. The chairman shall serve the subpoena in the manner provided by law.