The Federal Circuit Affirms the Delaware District Court’s Summary Judgment of Invalidity for Failure to Disclose the Best Mode

In Wellman, Inc. v. Eastman Chemical Co., No. 2010-1249 (Fed. Cir. Apr. 29, 2011), the Federal Circuit affirmed the U.S. District Court for the District of Delaware’s grant of summary judgment on invalidity of Wellman’s patent claims for failure to disclose the best mode.

Plaintiff-patentee Wellman filed an action against Eastman Chemical, claiming it infringed U.S. Patent Nos. 7,129,317 (the ’317 patent) and 7,094,863 (the ’863 patent), which claim polyethylene terephthalate (PET) resins for use in plastic beverage containers. More particularly, the Wellman patents disclose “slow crystallizing” PET resins that purportedly retain exceptional clarity and do not shrink or become hazy from crystallization when “hot-filled” with product at temperatures of 180° C to 205° C.

Eastman Chemical defended by moving for summary judgment of invalidity on the grounds of indefiniteness and failure to set forth the best mode of practicing the claimed invention under 35 U.S.C. § 112, ¶ 1. The district court found that the patents were invalid, and Wellman appealed.

In its opinion, the Federal Circuit reaffirmed the law of “best mode.” Determining compliance with the best-mode requirement requires a two-prong inquiry. First, it must be determined whether, at the time the application was filed, the inventor possessed a best mode for practicing the invention. This is a subjective inquiry that focuses on the inventor’s state of mind at the time of filing. Second, if the inventor has a subjective preference for one mode over others, the court must then determine whether the inventor “concealed” the preferred mode from the public. The second prong inquires into the inventor’s disclosure of the best mode and the adequacy of that disclosure to enable one of ordinary skill in the art to practice that part of the invention. This second inquiry is objective, depending on the scope of the claimed invention and the level of skill required in the relevant art.

With respect to the first inquiry, the Federal Circuit agreed with the district court’s finding that the inventors possessed a best mode for practicing the invention. In particular, the district court found, based on the testimony of the inventors, that one inventor believed a specific formula for a slow-crystallizing, hot-fill PET called Ti818 to be the best mode of carrying out the claimed invention. The parties agreed that all but five of the asserted claims encompassed Ti818. Additionally, the Federal Circuit agreed with the district court that another inventor believed the use of carbon black (N990), an ingredient in its Ti818 PET formula, to be the best mode at the time of filing the application.

With respect to the second inquiry, the Federal Circuit agreed with the district court’s finding that Wellman effectively concealed the best mode from the public. Specifically, the district court found, and the Federal Circuit agreed, that Wellman effectively concealed the recipe for Ti818 by identifying preferred concentration ranges for certain ingredients that excluded those used in Ti818 and by identifying preferred particle sizes for an additive other than that used in Ti818. Thus, Wellman did not disclose the specific recipe for Ti818 or any other specific PET resin recipes. “By masking what at least one inventor considered the best of these slow-crystallizing resins, Wellman effectively concealed its recipe for Ti818.”

The Federal Circuit agreed with the district court and further held that Wellman not only failed to disclose its use of carbon black N990 in its Ti818 PET formula, but also deliberately chose to protect that ingredient as a trade secret, and, therefore, “intentionally concealed” the best mode. The Federal  Circuit found that the Wellman patents “lead away” from the use of carbon black N990 in Ti818.

While affirming the district court’s decision on invalidity based on the best mode, however, the Federal Circuit reversed the district court’s grant of summary judgment on the issue of indefiniteness. Specifically, the Federal Circuit found that the district court erred when it concluded that the patents did not provide sufficient guidance to those skilled in the art for construing the temperature (TCH) at which the sample crystallized the fastest during heating in a differential scanning calorimetry machine. The specifications of the patents supported construing the TCH term to require testing of amorphous materials.

The Federal Circuit affirmed the district court’s summary judgment that all asserted claims of the ’317 and ’863 patents that covered the PET recipe Ti818 were invalid for failure to disclose the best mode of practicing the claimed invention. The Federal Circuit, however, reversed the district court’s judgment that the asserted claims were indefinite under 35 U.S.C. § 112, ¶ 2, and remanded the case for further proceedings.

A copy of the opinion can be found at