Previously, we explored what types of amendments to claims under post-grant review can trigger intervening rights.
As you may recall, claim amendments in current post grant proceedings at the USPTO (i.e., reexamination/reissue) create intervening rights. 35 U.S.C. 307 (ex parte) and 35 U.S.C. 316 (inter partes) describe the impact of amending claims in patent reexamination, incorporating 35 USC 252 (relating to intervening rights in reissue applications). In essence, the doctrine of intervening rights forecloses the recovery of past damages for patent infringement if a claim is amended after issuance of the patent.
The case of Kim v. The Earthgrains Co., k/n/a Sara Lee Bakery Group Inc., 01-cv-3895 (N.D. Ill.), presented the issue of whether a change in the transitional phrase (i.e., legally operative terms) of a patent claim could trigger intervening rights.
Transitional phrases such as “comprising” and “consisting of” connect the preamble language to the claim’s body and indicate whether the limitations in the body are “open” or “closed.”
In the reexamination proceeding (90/007,671) concurrent to the Kim v. Earthgrains case, plaintiff Kim consented to changing the transitional phrase in two of the asserted claims from “consisting essentially of” to “consisting of.” The record of the reexamination proceedings shows that the examiner believed the amendments necessary to overcome the then-outstanding prior art rejections (other amendments were also included but seemed unnecessary, the Patent Holder prosecuted the reexaminations pro se).
Subsequently, in the litigation, defendant The Earthgrains Co. moved for partial summary judgment that the applicable damages period did not begin until the date that the reexamination certificate issued. The basis for the motion was that the change to the transitional phrase was substantial and therefore barred recovery for infringement damages prior to the issuance of the reexamination certificate, under 35 U.S.C. §§ 252 and 307(b). This motion was significant because the litigation had been pending for nearly eight years when the reexamination certificate issued. If Earthgrains prevailed, all of the damages accruing up to the issuance of the reexamination certificate would be erased. The district court agreed with Earthgrains.
Not surprisingly, the court determined that the change in the transitional phrase meant that “the class of additional elements which may be added to the inventions in [the amended claims] has been changed from ‘elements which do not materially affect the basic and novel properties of the invention’ to ‘elements which are unrelated to the invention or are unavoidable impurities.'” In other words, the phrase “consisting of” did not encompass the scope of the original claims which used the transitional phrase “consisting essentially of.” Accordingly, the court concluded that the claims in the certificate of reexamination were not “substantially identical” to the originally issued claims.
The outcome of the intervening rights determination is hardly surprising to most post grant practitioners. On the other hand, the pro se Patent Holder was likely quite surprised that such a minor word change could have such devastating results.