Indiana Code Title 8. Utilities and Transportation § 8-1-3-5

Sec. 5. A copy of any assignment of errors or of cross-errors filed in the court of appeals shall be served by mail, on or before the date of such filing, upon all parties or their attorneys of record as shown by the commission record filed.  Copies of briefs shall be served, by mail, upon only the attorney general and those parties or their attorneys of record who have filed an appearance or assignment of errors with the clerk of the supreme court.