In all contested cases, printed or typewritten briefs may be filed in the discretion of the Commission, on behalf of any or all parties in interest. Unless the Commission indicates otherwise, such briefs shall be filed and copies served on the other parties in interest within the time hereinafter provided:
A sufficient number of copies of all briefs must be prepared to provide for service as aforesaid upon the adverse parties, and to provide at least six (6) copies, if typewritten, or ten (10) copies, if printed, for the use of the Commission.
W. Va. Code R. § 171-2-16