37 CFR 353.5: Participation not required.

In any case in which a response to a rehearing motion is allowed, or rehearing is granted, an opposing party shall not be required to participate in the rehearing. The Copyright Royalty Judges will not draw any negative inference from a lack of participation in a rehearing. Nonparticipation in rehearing proceedings may limit the scope of their participation in judicial review proceedings as set forth in 17 U.S.C. 803(d)(1).