Ambiguous claim language is limited to specific embodiment that was referred to as the invention

In Rhodia Chimie v. PPG Indus. Inc. (04/11/05 - No. 04-1246), a panel of the Federal Circuit ruled in a patent infringement dispute on claim construction, evidence exclusion, and prosecution history estoppel issues. The patent at issue involved silicon powders described in the claim as "dust-free and non-dusting".

The court first affirmed the district court's claim construction of the term "dust-free and non-dusting." The panel held that the district court had properly ruled that "dust-free" did not mean no dust at all because that would have excluded the preferred embodiment described in the specification. The district court then intepreted "dust-free" by reference to a DIN test referenced in an example in the specification. The panel agreed with this approach in order to resolve the otherwise ambiguous claim language:

We agree with the district court that the reference to the DIN test results for Example 5, as provided in the written description, reconciles the ambiguous claim language with the inventor's disclosure. Comark Communications, Inc. v. Harris Corp., 156 F.3d 1182, 1187 (Fed. Cir. 1998) (indicating that interpreting claim language in light of the specification is proper when a term is "so amorphous that one of skill in the art can only reconcile the claim language with the inventor's disclosure by recourse to the specification"). As such, the court's construction of the term "dust-free and non-dusting" does not contravene the basic teaching that limitations from the specification should not be imported to the claims. . . . Furthermore, this construction is consistent with the proposition that "when the preferred embodiment is described in the specification as the invention itself, the claims are not necessarily entitled to a scope broader than that embodiment." Modine Mfg., 75 F.3d at 1551.

The Rhodia court also refused to allow plaintiff to rely on the doctrine of equivalents with respect to the "dust-free" limitation. The court noted the limitation was a narrowing amendment made during prosecution, and application of the doctrine of equivalents was therefore barred by Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 344 F.3d 1359, 1365 (Fed. Cir. 2003) (en banc)). The patentee's surrender of claim scope as to non-dust free powders was not tangential, even though the accused product was not part of the prior art at the time of the narrowing amendment. Contrary to plaintiff's argument, the amendment to include the "dust-free" limitation was not tangential.

The panel also affirmed a district court ruling preventing the plaintiff from introducing late-produced DIN dust tests. The plaintiff had argued that it did not know to do these tests until after the court's claim construction ruling. The Federal Circuit disagreed, holding that plaintiff was unreasonable in waiting to perform these tests until late in the discovery period.

The panel reversed the district court's grant of summary judgment on one product. Plaintiff had sought to introduce evidence showing dust measurements on an allegedly infringing product, but the dust measurements had been taken before the patent issued. The panel held that the district court erred in excluding this evidence and granting summary judgment. The pre-issuance evidence was relevant in attempting to prove that the accused product infringed after the patent issued, creating a disputed issue of material fact.

Finally, the court affirmed another claim construction ruling, rejecting plaintiff's argument that disclaimers made during the prosecution history were limited to its process claims and did not affect its product claims. The court stated:

"There is no indication that Rhodia attempted to limit these disclaimers to its process claims. Rhodia was required to distinguish both its product and process claims from the inventions of Biegler and Brandt and it did so by focusing on the necessity of using liquid pressure nozzle sprayers and pulverized slurries to obtain its claimed product."