I. APPLICATION FILED ON OR AFTER SEPTEMBER 16, 2012

In applications filed on or after September 16, 2012, any power of attorney must be signed by the applicant or patent owner (for a patent, including a patent in a supplemental examination or reexamination proceeding). See 37 CFR 1.32(b). For an assignee to revoke a previously given power of attorney and/or grant a power of attorney, the assignee must become the applicant under 37 CFR 1.46(c). See MPEP §§ 402.02(a) and 402.05(a). See MPEP § 325 for details pertaining to establishing the right of an assignee to take action in an application filed on or after September 16, 2012.

II. APPLICATION FILED BEFORE SEPTEMBER 16, 2012

In applications filed before September 16, 2012, the assignee of record of the entire interest can revoke the power of attorney of the applicant unless an "irrevocable" right to prosecute the application had been given as in some government owned applications.

37 C.F.R. 3.71 (pre-AIA) Prosecution by assignee.

1. (a) Patents — conducting of prosecution. One or more assignees as defined in paragraph (b) of this section may, after becoming of record pursuant to paragraph (c) of this section, conduct prosecution of a national patent application or a reexamination proceeding to the exclusion of either the inventive entity, or the assignee(s) previously entitled to conduct prosecution.
2. (b) Patents — assignee(s) who can prosecute. The assignee(s) who may conduct either the prosecution of a national application for patent or a reexamination proceeding are:
   1. (1) A single assignee. An assignee of the entire right, title and interest in the application or patent being reexamined who is of record, or
   2. (2) Partial assignee(s) together or with inventor(s). All partial assignees, or all partial assignees and inventors who have not assigned their right, title and interest in the application or patent being reexamined, who together own the entire right, title and interest in the application or patent being reexamined. A partial assignee is any assignee of record having less than the entire right, title and interest in the application or patent being reexamined.
3. (c) Patents — Becoming of record. An assignee becomes of record either in a national patent application or a reexamination proceeding by filing a statement in compliance with § 3.73(b) that is signed by a party who is authorized to act on behalf of the assignee.
4. (d) Trademarks. The assignee of a trademark application or registration may prosecute a trademark application, submit documents to maintain a trademark registration, or file papers against a third party in reliance on the assignee’s trademark application or registration, to the exclusion of the original applicant or previous assignee. The assignee must establish ownership in compliance with § 3.73(b).

See pre-AIA 37 CFR 1.36 in MPEP § 402.05(b).

A power of attorney by the assignee of the entire interest revokes all powers given by the applicant and prior assignees if the assignee establishes their right to take action as provided in pre-AIA 37 CFR 3.73(b). See MPEP § 324. Ordinarily, the applicant will still have access to the application (MPEP § 106).

In an application that has been accorded status under pre-AIA 37 CFR 1.47(a), or for which status under pre-AIA 37 CFR 1.47(a) has been requested, a power of attorney given by the inventors who have signed the declaration (available inventors) may be revoked by an assignee of the entire interest of the available inventors (i.e., the applicant). See pre-AIA 37 CFR 1.32(b)(4). Rights of the assignee to take action may be established as provided in pre-AIA 37 CFR 3.73(b) and MPEP § 324.

Form PTO/SB/80 may be used by an assignee of the entire interest of the applicant to revoke a power of attorney and appoint a new power of attorney. The assignee would sign the power of attorney, and either the assignee or the newly appointed practitioner, having authority to take action on behalf of the assignee would sign a statement under pre-AIA 37 CFR 3.73(b) for the application in which the general power of attorney is to be used. See MPEP § 324, subsection V. for who can sign the Statement Under pre-AIA 37 CFR 3.73(b) (Form PTO/SB/96 or equivalent).