E.I. DUPONT DE NEMOURS & CO. v. UNIFRAX I LLC
- Apr 17 2019 |
- Category: CAFC Updates
Unifrax appeals from the district court’s claim construction and denial of its motions for judgment of non-infringement and invalidity as a matter of law after a jury found that Unifrax’s flame barrier product infringed the asserted DuPont patent and that Unifrax failed to prove the asserted patent was invalid. Unifrax challenges the district court’s claim interpretation and argues that the term “100% by weight” does not allow for any amount of organic additives in the refractory layer, but considering whether the context of the entire patent and other intrinsic evidence supports such an interpretation, the CAFC holds that it does not. The CAFC notes that familial patents inform the construction of a claim term and are appropriately treated as intrinsic evidence, and when a parent application includes statements involving “common subject matter” with the terms at issue, those statements are relevant to construction of the terms in the child patent. The CAFC discerns no error in the district court’s construction of “100% by weight” to mean there is no carrier material such as resin, adhesive, cloth, or paper in addition to the inorganic platelets. The CAFC also finds that substantial evidence supports the jury’s infringement verdict and the jury’s verdict that the prior art does not anticipate the asserted claims of the patent. Thus, the CAFC affirms. Judge O’Malley dissents, because in his view the erroneous construction of “100% by weight” ignores the plain meaning of “100%” and introduces more ambiguity than it resolves.