39 CFR §955.9

After reviewing the pleadings and appeal file documents, the Board may require the parties to submit prehearing briefs in any case in which a hearing will be held. Either party may also request permission to file a prehearing brief. If the Board grants that request, it will allow the other party to also file a prehearing brief. If prehearing briefs are submitted, they must be filed at least 15 days before the date set for hearing, or as otherwise ordered by the Board.