A claim noted as allowable may be rejected only after a primary examiner has considered all the facts. An Office action rejecting a previously allowed claim must be signed by a primary examiner. See MPEP § 1004.
Great care should be exercised in making such a rejection.
PREVIOUS ACTION BY DIFFERENT EXAMINER
Full faith and credit should be given to the search and action of a previous examiner unless there is a clear error in the previous action or knowledge of other prior art. In general, an examiner should not take an entirely new approach or attempt to reorient the point of view of a previous examiner, or make a new search in the mere hope of finding something. Amgen, Inc. v. Hoechst Marion Roussel, Inc., 126 F. Supp. 2d 69, 139, 57 USPQ2d 1449, 1499-50 (D. Mass. 2001).
Because it is unusual to reject a previously allowed claim, the examiner should point out in his or her office action that the claim now being rejected was previously allowed by using Form Paragraph 7.50.
¶ 7.50 Claims Previously Allowed, Now Rejected, New Art
The indicated allowability of claim  is withdrawn in view of the newly discovered reference(s) to . Rejection(s) based on the newly cited reference(s) follow.
- 1. In bracket 2, insert the name(s) of the newly discovered reference.
- 2. Any action including this form paragraph requires the signature of a Primary Examiner. MPEP § 1004.