Federal Circuit Says Texas Court Erred in Finding Viscometer Patent Claim Indefinite

The U.S. Court of Appeals for the Federal Circuit (CAFC) today ruled in a precedential decision that the U.S. District Court for the Southern District of Texas incorrectly found the term “enlarged chamber” indefinite, but affirmed the court’s construction of another claim term.

The case stems from Grace Instrument Industries, LLC’s May 19, 2020, suit against Chandler Instruments Company, LLC for infringement of its U.S. Patent No. 7,412,877 through the sale of Chandler’s Model 7600 viscometer. The ‘877 patent is titled “High Pressure Viscometer with Chamber Preventing Sample Contamination.” A Viscometer is used to measure the viscosity of a fluid.

On July 1, 2021, the court issued a claim construction order in part holding that that the term “enlarged chamber” in claims 1 and 4 of the patent is indefinite. The district court reasoned that “enlarged” is a “term of degree” that “necessarily calls for some comparison against some baseline,” and that the claims therefore did “’not provide the requisite objective boundaries’ for a skilled artisan.” While Grace argued that the baseline for “enlarged” was defined by the prior art, the district court disagreed.

On the second claim term at issue, “means for driving said rotor to rotate located in at least one bottom section,” the parties “agreed that the function is ‘driving said rotor to rotate,’ but disputed the means and whether the phrase ‘located in at least one bottom section’ modifies ‘rotor,’ as Grace contended, or ‘means for driving,’ as Chandler argued.” The district court adopted Chandler’s proposed construction in its entirety.

In its discussion of the indefiniteness ruling, the CAFC said that the district court erred in its reliance on extrinsic evidence, rather than the intrinsic record, to construe the claim. The court explained:

“[A]lthough “enlarged chamber” is not a term of art, the intrinsic record sufficiently guides a skilled artisan to the meaning of that term as used in the ’877 patent. The district court erred in its reliance on extrinsic evidence—i.e., dictionary definitions—that contradict the scope and meaning of “enlarged chamber” that a skilled artisan would ascertain by reading the intrinsic record.”

Citing Trs. of Columbia Univ. v. Symantec Corp., the CAFC reminded the district court that “[t]he only meaning that matters in claim construction is the meaning in the context of the patent.”

Unlike the case of Liberty Ammunition, Inc. v. U.S., where the CAFC found that there was no objective boundary in the intrinsic record for a skilled artisan, and on which the district court incorrectly relied, the ‘877 patent’s intrinsic record “provides an objective boundary for a skilled artisan—i.e., the ‘enlarged chamber’ must be large enough to prevent, during elevated pressurization, commingling of sample and pressurization fluids in the lower measurement zone,” said the court.

The court went on to note, however, that the indefiniteness question may not yet be fully resolved and “may require further fact-finding on remand” but declined to address the various arguments raised by both Chandler and Grace on that issue in the first instance.

The CAFC ultimately construed the term “enlarged chamber” to mean “a chamber that is large enough to contain excess test sample prior to pressurization to prevent mixing of the test sample and pressurization fluid in the lower measurement zone when the test sample is pressurized to maximum rated pressure” and vacated the district court’s holding of indefiniteness and related invalidity determinations.

As to construction of the term “means for driving said rotor to rotate located in at least one bottom section,” the CAFC disagreed with Grace’s contention that “the court erred in finding that the term ‘bottom section’ refers to the bottom section of the viscometer rather than the bottom section of the pressure vessel and in finding that ‘located in at least one bottom section’ modifies ‘means for driving’ rather than ‘rotor.’” The CAFC said that “the most natural reading of limitation 4(c) requires the phrase ‘located in at least one bottom section’ to modify ‘means for driving’ and not ‘rotor,’” and that “the claimed ‘bottom section’ refers to the bottom section of claim 4’s viscometer, not the pressure vessel component of the viscometer.”

The CAFC thus ultimately affirmed the district court’s construction of “means for driving said rotor to rotate located in at least one bottom section” and rejected Grace’s remaining arguments.

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Author: billperry