G.D. Searle, LLC (referred to as "Pfizer") appealed from a final judgment entered by the U.S. District Court for E.D. Va.  The trial court invalidated the relevant claims of Pfizer’s reissued U.S. Patent No. RE44,048 based on obviousness-type double patenting.

This case involves a patent family based on U.S. Patent Application No. 08/160,594  (the '594 application).  After the '594 application was filed, a three-way restriction was issued by the USPTO, restricting species related to a compound, a composition of matter, and a method-of-use.  Pfizer elected the compound species, which eventually issued as U.S. Patent No. 5,466,823.  Before this patent issued, Pfizer filed U.S. Patent Application No. 08/457,059  (the '059 application), a divisional application directed the composition species, which issued as U.S. Patent No. 5,563,165  (the '165 patent).  Before the restriction in the '594 application, Pfizer also filed U.S. Patent Application No. 08/223,629  (the '629 application), a continuation-in-part of the '594 application, which eventually issued as U.S. Patent No. 5,521,207, and was directed to the composition species.  Pfizer also filed PCT/US94/12720 (the '720 application), a continuation-in-part of the '629 application, which proceeded to the national stage in the U.S. as U.S. Patent Application No. 08/648,113 (the '113 application) and eventually issued as U.S. Patent No. 5,760,068 (the '068 patent), which was the only issued patent in the family directed to the method-of-use species from the '594 application.

Prior to this case, Pfizer brought suit in Pfizer, Inc. v. Teva Pharmaceuticals USA, Inc., 518 F.3d 1353 (Fed Cir. 2008), a patent infringement action brought by Pfizer on the '068 patent.  In that case, the relevant method-of-use claims of '068 patent were held invalid for obviousness-type double-patenting over the composition claims of the earlier '165 patent.  

In  the earlier case, Pfizer attempted to invoke the "safe harbor" provisions of 35 U.S.C. §121, which can protect a patent that issues on a divisional application from invalidation based on a related patent that issued on an application as to which a restriction requirement was made, or on an application filed as a result of such a requirement. However, the Federal Circuit ruled against Pfizer, holding that the protection afforded by §121 to applications (or patents issued therefrom) filed as a result of a restriction requirement is limited to divisional applications, and the ’068 patent issued from a continuation-in-part, not a divisional application.

Not to be deterred, Pfizer set out to turn the '068 patent into a divisional by filing Reissue Application No. 12/205,319 ('the '319 application). In the Reissue Declaration, Pfizer asserted that it had erred in prosecuting the application leading up to the ’068 patent as a continuation-in-part, rather than as a divisional application, and that the error had resulted in invalidating the relevant claims of the ’068 patent for obviousness-type double patenting.  The preliminary amendment that accompanied the initial reissue declaration attempted to amend the '068 patent to remove portions of the '068 patent that were not present in the '594 application, and to designate the '113 application as a divisional of the '594 application, while removing the priority claim to the  '629 application.  The Examiner rejected the preliminary amendment, finding that this "error" was not correctable by reissue, but Pfizer then submitted an additional reissue declaration citing technical errors rendering the claims of the '068 patent indefinite.  Pfizer was allowed to correct those technical errors, and also to make the additional changes conforming the '068 patent to a divisional of the '594 application.  The USPTO eventually allowed the claims of the '319 application, which issued as RE44,048  (RE '048).

Pfizer immediately brought the instant suit alleging infringement of the RE '048 patent, and the District Court found the relevant claims invalid.  Pfizer then appealed to the Federal Circuit, where the main issues to be considered were:

                 1. Whether 35 U.S.C. §251 authorized the PTO to reissue the ’068 patent under the circumstances

                 2. Assuming reissue was authorized, whether the safe harbor provision of 35 U.S.C. §121 applies to the RE ’048 patent and protects it from invalidation based on the ’165 patent

The Federal Circuit held that, even assuming that it was proper to grant the reissue patent, safe harbor provisions do not apply, and the claims are invalid.  The court noted that it applies a "strict test" for §121, given the potential windfall a patent term extension could provide to a patentee.

The court reasoned that the reference '165 patent issued on a divisional of the '594 application.  The RE '048 patent is not entitled to safe harbor protection, because it did not issue on either the '594 application or a divisional of the '594 application. Instead, the RE ’048 patent issued from the ’319 application, a reissue of the ’068 patent, which in turn issued from the ’113 application  The ’113 application cannot be a divisional of the ’594 application because it contains new matter that was not present in the ’594 application.  When the ’113 application issued as the ’068 patent, the public was not free to practice that new matter.  According to the court, fairness to the public does not permit Pfizer to convert the ’113 application into a division of the original ’594 application, and thereby take advantage of the safe harbor provision, simply by designating it as a divisional application years after the fact.  

This case serves as a reminder to practitioners of the potential dangers when dealing with applications that are part of extensive patent families.  A comprehensive strategy is extremely helpful when dealing with complicated chains of priority, especially when any of the links in the chain has been subject to a restriction requirement.  It should also be noted that Continuations-in-Part do not maintain all of the same rights as Continuations or Divisionals, and care should be taken so that priority is not lost.