Sec.  1.263   Proposed findings and conclusions.

   (a) Each party to the proceeding may file proposed findings of fact and
   conclusions, briefs, or memoranda of law: Provided, however, That the
   presiding officer may direct any party other than Commission counsel to file
   proposed findings of fact and conclusions, briefs, or memoranda of law. Such
   proposed findings of fact, conclusions, briefs, and memoranda of law shall
   be filed within 20 days after the record is closed, unless additional time
   is allowed.

   (b) All pleadings and other papers filed pursuant to this section shall be
   accompanied by proof of service thereof upon all other counsel in the
   proceeding; if a party is not represented by counsel, proof of service upon
   such party shall be made.

   (c) In the absence of a showing of good cause therefor, the failure to file
   proposed findings of fact, conclusions, briefs, or memoranda of law, when
   directed to do so, may be deemed a waiver of the right to participate
   further in the proceeding.

   (5 U.S.C. 557)