Water Meter Patent Nixed by PTAB Using Product-by-Process Analysis, Affirmed at Federal Circuit

By Natalie Grace | August 24, 2022

In a precedential opinion of August 12, 2022, the Federal Circuit affirmed a Patent Trial and Appeal Board decision invalidating the claims of U.S. Patent No. 8,806,957 directed to an ultrasonic flow meter housing.  The invalidation hinged on construction of the phrase “a monolithic polymer structure being cast in one piece,” which the PTAB board determined was a product-by-process recitation not entitled to patentable weight because it is not descriptive of the housing’s structure, only the process of casting.


“Product-by-process claims… enable an applicant to claim an otherwise patentable product that resists definition by other than the process by which it is made.” In re Thorpe, 777 F. 2d 695, 697 (Fed. Cir. 1985).  In Thorpe, the Court explained that “[i]f the product in a product-by-process claim is the same as or obvious from a product of the prior art, the claim is unpatentable even though the prior product was made by a different process. Id. (citations removed).  Thus, when the board identified the claim as containing a product-by-process recitation, the main question became whether the process confers “structural and functional differences” to the claimed housing.  Amgen Inc. v. F. Hoffmann-La Roche Ltd., 580 F.3d 1340, 1373 (Fed. Cir. 2009).


In Kamstrup A/S v. Axioma Metering UAB[1], the court initially identified the verb “being” as indicative of claiming a process.  Next, the court looked for “’structural and functional differences between a structure ‘cast in one piece’ and a structure manufactured using another method.”  In doing so, the court noted that Kamstrup, in its arguments, stated that the structures of the cited prior art “cannot be cast in a single mold using conventional die cast injection molding technologies.” The court, in response, identified two deficiencies in this reasoning: 1) “the argument is merely that the claim element describes a manufacturing method with some inherent limitations;” and 2) “the alleged structural and functional difference that Kamstrup identifies is detached from the claim[]” language which recites “cast in one piece” not “cast in one mold.” [2]


In takeaway, this decision points to the importance of describing benefits of a design in the specification, including its structural and functional uniqueness in view of the state of the art where the state-of-the-art bears close similarity to the design being protected.  Further, the decision points to the importance of differentiation of claim language, within a claim set and/or within a patent family, to avoid unforeseen constructions (e.g., product-by-process) and questions of scope (e.g., “molded” vs. “cast in one piece”) that could catch a patent holder unaware and lead to loss of patent coverage for the invention.


[1] case number 21-1923, at the U.S. Court of Appeals for the Federal Circuit

[2] Further, the court noted that the board found “that the extrinsic evidence does not exclusively show that ‘cast in one piece’ means ‘cast in one mold.’”