In all complaints, proceedings, contests, or controversies by or before the Commission instituted by the Commonwealth or by the Commission of its own motion, the Commonwealth shall be complainant, and the party against whom the complaint is preferred, or the proceeding instituted, shall be the defendant. Any party complainant or defendant in any complaint, proceeding, contest, or controversy shall be entitled to process, to convene parties, compel the attendance of witnesses, or the production of books, papers, and documents in any proceeding or hearing before the Commission.