39 Miss. Code. R. 1-6-125
A proceeding shall not be dismissed at the filing party's instance except upon order of the Commission and upon such terms and conditions as the Commission deems proper.
The Commission may, upon its own motion or upon a motion by the Staff or by motion made by any other party, dismiss or remand to the files a proceeding for failure of the filing party to prosecute or to comply with any relevant provision of these rules, the Act or any Order of the Commission.
Any application, petition, complaint, or other matter filed with the Commission in which no activity of record or written order is taken for a period of nine months shall be automatically dismissed without prejudice for lack of prosecution. However, a matter will not be dismissed for inactivity where a motion is pending before the Commission. Computation of the nine month period shall begin with the date of the last filing or other activity of record concerning the matter. In order to avoid automatic dismissal, a motion must be made or an order issued, properly signed and filed with the Commission before the nine month period expires. A party may file a motion to extend the time for an additional three months; however, the Commission, on its own motion, may extend or waive this portion of the rule to conclude the docket. For the purposes of this rule, activity of record shall include any application, petition, complaint, motion, brief, or other pleading filed with the Commission as well as any hearing or oral argument held in this matter.
39 Miss. Code. R. 1-6-125