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Failure to Disclose Method of Making Starting Material for Cipro® Is Not a Violation of Best-Mode Requirement

August 09, 2002

Decision icon Decision

Last Month at the Federal Circuit - September 2002

Judges: Clevenger (author), Dyk, and Rader (concurring)

In Bayer AG v. Schein Pharmaceuticals, Inc., No. 01-1286 (Fed. Cir. Aug. 9, 2002), the Federal Circuit affirmed the district court’s finding that U.S. Patent No. 4,670,444 and Reexamination Certificate B1 4,670,444 (collectively “the ‘444 patent”) directed to ciprofloxacin were not invalid for failure to disclose the best mode.

Bayer AG and Bayer Corporation (collectively “Bayer”) sued Schein Pharmaceuticals, Inc. and several other generic-drug manufacturers (collectively “Schein”) under 35 U.S.C. § 271(e)(2) for infringement of the ‘444 patent, after Defendants filed an ANDA directed to generic versions of ciprofloxacin, i.e., CIPRO®. Schein raised an affirmative defense of invalidity, arguing that the ‘444 patent could not claim the benefit of priority of the parent application under either 35 U.S.C. §§ 119 or 120 because the parent application was invalid for failure to disclose the best mode.

The application that matured into the ‘444 patent was filed as a continuation application subsequent to the issuance of four counterpart foreign patents. According to Schein, Bayer should have been precluded from relying on the filing date of the original U.S. application, because it did not contain the inventor’s best mode of making the starting material necessary to make ciprofloxacin. If Schein had been successful in this argument, the ‘444 patent would have been invalid under 35 U.S.C. § 102(d) based on the intervening filing and issuance of the four counterpart foreign patents. However, the district court granted Bayer’s motion for SJ, holding that the original U.S. application satisfied the best-mode requirement and, thus, that the parent application was entitled to the benefit of priority under 35 U.S.C. § 120. The court did not address the issue of priority under 35 U.S.C. § 119.

On appeal, the Federal Circuit affirmed the district court’s finding that Bayer’s original U.S. application for ciprofloxacin adequately disclosed the inventor’s best mode.

The Court agreed with the district court’s finding that the inventor had an undisclosed preference for making the preferred starting compound, 6-fluoroquinolinic acid (“6-FQA”). Although the application disclosed the general class of compounds used as a starting material, it did not disclose the inventor’s preferred method of synthesizing 6-FQA, which included the use of a particular precursor to 6-FQA. The Court concluded, however, that only if the inventor’s stated preference is directed to a claimed element or materially affects the properties of a claimed element, will a best-mode violation invalidate a patent. According to the Court, neither the 6-FQA nor a method for making it were claimed or would materially affect the claimed compound, ciprofloxacin. Accordingly, the inventor’s undisclosed preference was not subject to the best-mode disclosure requirement, and as such, the lack thereof did not preclude Bayer from relying on its original U.S. application for priority under 35 U.S.C. § 120 or invalidate the ‘444 patent under 35 U.S.C. § 102(d).

In a concurring opinion, Judge Rader contended that the Court went too far in setting forth the first step of its test. In his opinion, the only issue to be decided is whether the element that the inventor has expressed a preference for is claimed. In this case, the district court did exactly that, finding that 6-FQA was not claimed and, therefore, was not required to be disclosed beyond enablement. It is not proper for a district court, when construing a claim, to extend the best-mode requirement beyond the claims and consider whether an unclaimed element “materially affects” the properties of the claimed invention. Such “dicta,” according to Judge Rader, will only serve to create conflict with other Federal Circuit precedent and to confuse the district courts in their analysis of whether the best-mode disclosure requirement is satisfied.