Originally published in outs & ins, vol. 4, no. 1, 2004.

Cancellation of claims has taken on greater significance in view of the recent decision in Ranbaxy Pharmaceuticals, Inc. and Ranbaxy Laboratories Limited v. Apotex, Inc., Federal Circuit Appeal No. 02-1429, decided 11-26-2003. Ranbaxy involved an appeal of a New Jersey District Court's denial of a preliminary injunction against Ranbaxy Pharmaceuticals and Ranbaxy Laboratories Limited, and held that a narrowing amendment can occur when a broad claim is canceled and an original dependent claim is rewritten in independent form.

Ranbaxy et al brought suit for a declaration of non-infringement of Apotex's U.S. Patent No. 5,847,118. Apotex filed a counterclaim alleging that Ranbaxy infringed the '118 patent and Apotex requested the court to issue a preliminary injunction.

The application which issued as the '118 patent was filed with one independent claim and nine dependent claims. Claim 1 was directed to a process of preparing amorphous cefuroxime axetil by steps which included dissolving crystalline cefuroxime axetil in a "highly polar organic solvent." In the first Official Action, claims 1, 8 and 10 were rejected as indefinite, claims 1, 2, 9 and 10 were rejected as obvious over prior art and claims 3-7 were indicated as allowable. In response, Apotex canceled claims 1-10 and submitted new claims 11-16. Claim 11 was similar to canceled claim 1 but further defined the "highly polar organic solvent" as being selected from the group consisting of a sulfoxide, an amide and formic acid. These solvents are identical to the solvents recited in canceled claims 3, 5 and 7. Claim 11 was allowed and became claim 1 of the '118 patent.

In the District Court action, Apotex alleged that Ranbaxy's process (which used acetic acid) infringed the '118 patent under the doctrine of equivalents. The District Court denied Apotex's request for a preliminary injunction on the basis that Apotex did not show a reasonable likelihood of success on the merits. The Federal Circuit agreed that Apotex could not make the required showing of infringement due to prosecution history estoppel since the narrowing amendment resulted in a complete bar of equivalents under Festo Corporation v. Shoketsu Kinsoku Kogyo Kabushiki Co., 234 F.3d 558, 56 USPQ2d 1865 (Fed. Cir. 2000) (en banc), vacated by 535 U.S. 722, 122 S.Ct. 1831, 62 USPQ2d 1705 (2002).

In its appeal, relying on Bose Corporation v. JBL, Inc, 274 F.3d 1354, 61 USPQ2d 1216 (Fed. Cir. 2001), Apotex argued that it had not made a narrowing amendment during prosecution of the '118 patent since independent claim 11 merely combined the features of claims 3, 5 and 7. The Federal Circuit disagreed stating that in Bose "[w]e did not squarely address the effect that rewriting a dependent claim into independent form may have on prosecution history estoppel.” With respect to prosecution of the ‘118 patent, the Federal Circuit stated that “[w]hile Apotex was merely rewriting a dependent claim into independent form, the effect on the subject matter was substantial.” In fact, the Federal Circuit stated that Apotex is "presumed to have surrendered the equivalents that may have been encompassed by ‘highly polar organic solvent’” and agreed with the District Court that Apotex had made a narrowing amendment for a substantial reason related to patentability.

The Federal Circuit then evaluated whether Apotex had overcome the presumption that it surrendered equivalents on the basis that (1) the equivalent was unforeseeable at the time the application was filed, (2) the rationale for the amendment bears no more than a tangential relation to the equivalent, or (3) the patentee could not reasonably be expected to have described the insubstantial substitute in question. Ranbaxy argued that (1) acetic was a foreseeable equivalent to formic acid and could have been included in the original claim and (2) because acetic acid and acetone have similar polarities and acetone was described in the background of the '118 patent, Apotex surrendered coverage for acetic acid. The Federal Circuit agreed with Ranbaxy.

In the District Court action, Apotex took the position that formic acid and acetic acid were known by chemists to exhibit similar properties and therefore were equivalent. However, the Federal Circuit concluded that because "it would have been foreseeable to literally include acetic acid in the claim," Apotex had not overcome the presumption that it surrendered coverage of acetic acid when it canceled original Claims 1-10 and presented new Claim 11.

Thus, the decision in Ranbaxy illustrates that a narrowing amendment can occur when a broad claim is canceled and an original dependent claim is rewritten in independent form. Such a narrowing amendment can result in prosecution history estoppel with respect to subject matter within the scope of the canceled claim but not literally covered by the rewritten claim.