Best Mode Requirement Is Satisfied Despite Failure to Disclose a Method for Making a Preferred Unclaimed Starting Material

Affirming the decision of the U.S. District Court for the District of New Jersey in a consolidated patent infringement suit in which Bayer AG sued four pharmaceutical companies for infringement of its patent covering a class of compounds including the antibiotic ciprofloxacin (Cipro), the U.S. Court of Appeals for the Federal Circuit found that the best mode requirement was satisfied despite Bayer’s failure to disclose a method of making a preferred unclaimed intermediate used for making the claimed compounds. Bayer AG v. Schein Pharmaceuticals, Inc. et al., Case No. 01-1286-1287 (August 9, 2002).

On cross-motions for summary judgement, the district court held that Bayer’s patent, U.S. 4,670,444 (the `444 patent), was entitled to the filing date of its parent application and, thus, was not invalid under 35 U.S.C § 102(d) over its own previously issued patents. On appeal, the defendants argued that the parent application was invalid for failure to disclose the best mode of carrying out the claimed invention contemplated by the inventor at the time of filing the application. The inventor of the `444 patent had discovered a way to increase antibiotic activity of a known compound. The general synthetic route to making the improved compound involves construction of an intermediate compound followed by further reaction of the intermediate. The inventor had difficulty constructing the intermediate compound and enlisted the help of another Bayer scientist who successfully synthesized a novel precursor of the intermediate compound (the Klauke compound). The `444 patent does not disclose the Klauke compound or its use in making the claimed final product (Cipro), but it does disclose a class of starting materials including the Klauke compound.

In reaching its decision, the district court had applied the two prong test for whether a disclosure satisfies the best mode requirement: determining first whether the inventor subjectively possessed a best mode of practicing his invention and, then, whether the parent application adequately disclosed that best mode. The district court determined that the scope of the claimed invention did not include any intermediate compounds but was limited to the end product, Cipro, and thereby disposed of the best mode allegation as outside the § 112, ¶1 reference to the "invention."

The Federal Circuit affirmed, using essentially the same analysis as the district court. As construed by the Federal Circuit, the invention consists of the final antibiotic products and not the starting materials. It was undisputed that at the time of filing the inventor had a preference for use of a starting material comprising a class of compounds including the Klauke compound, to make the intermediate product that was then reacted to form the claimed end product. However, the court disagreed with the defendants’ contention that Bayer’s failure to disclose the route to making the intermediate was a fatal flaw: "Not every preference constitutes a best mode of carrying out the invention." The court stated a rule that "unclaimed subject matter unrelated to the properties of the invention is not subject to the best mode disclosure requirement."

The court also disagreed with the defendants’ contention that disclosure of the intermediate is mandatory in this case because it is novel. The court noted that when a novel compound is necessary to practice the best mode, the best mode must be enabled. However, in the present case the court found the best mode to be enabled by the disclosure of the class of starting compounds, noting that since the inventor’s preferred method of making the intermediate does not materially affect carrying out the claimed invention, it need not be disclosed to comply with the best mode requirement.

In a concurring opinion, Judge Rader characterized the Federal Circuit’s opinion as "a new trap in the best mode minefield," but "[f]ortunately, . . . mostly dicta." Judge Rader strongly disagreed with the court’s use of an "effect on properties" test to identify best mode.