37 CFR §227.2

1. (a)General. If a respondent or counterclaim respondent fails to appear or ceases to participate in the proceeding and the Board elects to proceed to a default determination, the Board shall require the claimant or counterclaimant to submit written direct testimony, as set forth in § 222.15(b) of this subchapter.
2. (b)Additional evidence. Following submission of the claimant's or counterclaimant's written testimony in support of a default determination, the Board shall consider the claimant's or counterclaimant's submissions and may request any additional evidence from the claimant or counterclaimant within the claimant's or counterclaimant's possession.