How can a claim for foreign priority be perfected after a patent has been issued?

A claim for foreign priority can be perfected after a patent has been issued through two main methods:

1. Certificate of Correction under 35 U.S.C. 255 and 37 CFR 1.323
2. Reissue application

The choice of method depends on the specific circumstances:

• A Certificate of Correction can be used if the requirements of 37 CFR 1.55 are met and no further examination is required.
• A reissue application is necessary if the requirements of 35 U.S.C. 119(a)-(d) or (f) were not satisfied in the patented application or its parent prior to issuance, or if further examination would be required.

The MPEP states: “The failure to perfect a claim to foreign priority prior to issuance of the patent may be cured via a certificate of correction under 35 U.S.C. 255 and 37 CFR 1.323, provided the requirements of 37 CFR 1.55 are met, or by filing a reissue application.” (MPEP 216.01)