When is reopening prosecution mandatory after Action Closing Prosecution (ACP) in inter partes reexamination?

Reopening prosecution is mandatory when the examiner decides to modify their position after receiving a submission from the patent owner pursuant to 37 CFR 1.951(a) and (b). This is necessary to give the patent owner an opportunity to address any changes adverse to their position.

According to MPEP 2673.01:

“The examiner should reopen prosecution where any new ground of rejection is made or any additional claim is rejected.”

This is typically done by issuing a non-ACP action, allowing the patent owner to retain full amendment rights.

To learn more:

• inter partes reexamination
• Action Closing Prosecution
• reopening prosecution
• patent examination