When is a reply brief required in a patent appeal?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

While a reply brief is normally optional, there are specific circumstances where it becomes mandatory. According to MPEP 1208:

“In response to the following, however, appellant is required to file either a reply brief to maintain the appeal or a reply under 37 CFR 1.111 to reopen prosecution: If appellant requests that the appeal be maintained in response to a new ground of rejection made in an examiner’s answer or a substitute examiner’s answer, the appellant must file a reply brief to address each new ground of rejection set forth in the answer in compliance with 37 CFR 41.37(c)(1)(iv) within two months from the mailing of the answer.”

Failure to file a required reply brief may result in the dismissal of the appeal.