Nystrom is the inventor and sole owner of the ’831 patent. He is a working carpenter and the owner of a two-truck, two-employee lumberyard. He has been in the business of building exterior decks for twenty-five years. TREX is a manufacturer of exterior decking planks made from composites of wood fibers and recycled plastic.

Nystrom sued TREX for infringing his 5,474,831 patent. Coming out of a messy litigation battle, Nystrom was dissatisfied with the District Court's claim construction, and its summary judgment grant of invalidity, and so appealed.

The context in which the CAFC stated its claim construction reasoning:

As this court recently articulated in our en banc decision in Phillips v. AWH Corp., “[i]t is a ‘bedrock principle’ of patent law that ‘the claims of a patent define the invention to which the patentee is entitled the right to exclude.’” 415 F.3d 1303, 1312 (Fed. Cir. 2005) (quoting Innova/Pure Water, Inc. v. Safari Water Filtration Sys., Inc., 381 F.3d 1111, 1115 (Fed. Cir. 2004)). Therefore, we begin our claim construction analysis with the words of the claim. Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1582 (Fed. Cir. 1996). The words of the claim are generally given their ordinary and customary meaning. Id. at 1582. The ordinary and customary meaning of a claim term “is the meaning that the term would have to a person of ordinary skill in the art in question at the time of the invention.” Phillips, 415 F.3d at 1313. The person of ordinary skill in the art views the claim term in the light of the entire intrinsic record. See id. Thus, the claims “must be read in view of the specification, of which they are a part.” Markman v. Westview Instruments, Inc., 52 F.3d 967, 979 (Fed. Cir. 1995) (en banc). “‘The construction that stays true to the claim language and most naturally aligns with the patent’s description of the invention will be, in the end, the correct construction.’” Phillips, 415 F.3d at 1316 (quoting Renishaw PLC v. Marposs Societa’ per Azioni, 158 F.3d 1243, 1250 (Fed. Cir. 1998)). In addition to the written description, “the prosecution history can often inform the meaning of the claim language by demonstrating how the inventor understood the invention and whether the inventor limited the invention in the course of prosecution, making the claim scope narrower than it would otherwise be.” Id. at 1317. In discerning the meaning of claim terms, resort to dictionaries and treatises also may be helpful. Id. at 1318. However, “undue reliance on extrinsic evidence poses the risk that it will be used to change the meaning of claims in derogation of the ‘indisputable public records consisting of the claims, the specification and the prosecution history,’ thereby undermining the public notice function of patents.” Id. at 1319 (quoting Southwall Techs., Inc. v. Cardinal IG Co., 54 F.3d 1570, 1578 (Fed. Cir. 1995)).

When different words or phrases are used in separate claims, a difference in meaning is presumed. Tandon Corp. v. United States Int’l Trade Comm’n, 831 F.2d 1017, 1023 (Fed. Cir. 1987)... Different terms or phrases in separate claims may be construed to cover the same subject matter where the written description and prosecution history indicate that such a reading of the terms or phrases is proper. Id. at 1023-24

Three claim terms were in contention: "board", "manufactured to have", and "convex top surface".

The claims at issue do not include any language describing the “board” as cut from a log or necessarily being made of wood... [But, an] examination of the term “board” in the context of the written description and prosecution history of the ’831 patent leads to the conclusion that the term “board” must be limited to wood cut from a log.

Phillips, 415 F.3d at 1321 (“The problem is that if the district court starts with the broad dictionary definition in every case and fails to fully appreciate how the specification implicitly limits that definition, the error will systematically cause the construction of the claim to be unduly expansive.”). What Phillips now counsels is that in the absence of something in the written description and/or prosecution history to provide explicit or implicit notice to the public—i.e., those of ordinary skill in the art—that the inventor intended a disputed term to cover more than the ordinary and customary meaning revealed by the context of the intrinsic record, it is improper to read the term to encompass a broader definition simply because it may be found in a dictionary, treatise, or other extrinsic source. Id.

The court cited the AquaTex case, defining "fiberfill", as precedent in limiting claim term breadth.

In light of our construction of “board” as encompassing only materials made from wood cut from a log, we see no error in the district court’s limitation of the phrase “manufactured to have” in claim 1 to woodworking techniques. The use of the phrase “manufactured to have” in reference to the top surface of the board is necessarily limited to manufacturing techniques related to wood.

The district court construed “convex top surface” to mean “an upper surface with an outward curve that has a ratio of its radius of curvature to width of the board between 4:1 to 6:1.”... Nystrom argues that the district court erred by ignoring the ordinary and customary meaning of this claim term, which is “an upper surface with an outward curve[.]”... The district court relied on statements Nystrom made during prosecution to distinguish the Zagelmeyer reference as limiting the expression “convex top surface” to a surface with a radius of curvature in the range of 4:1 to 6:1... The district court erred in its analysis of the prosecution history. Nystrom’s statements were expressly directed to issued claim 16. There is no indication that Nystrom intended the term “convex top surface” in all of the pending patent claims to be limited to a specific radius of curvature ratio. The prosecution history did not redefine or disclaim “convex top surface” in claim 1 to be limited to a particular radius of curvature ratio. Accordingly, we hold that the correct construction of the expression “convex top surface” as used in claim 1 is the ordinary and customary meaning of an upper surface that curves or bulges outward, as the exterior of a sphere.

The prosecution tip here is to limit claim construction constrictions to specific claims if possible, avoiding blanket statements that may affect otherwise unrelated claims.

As to invalidity, the CAFC reversed the District Court, which had granted summary judgment based upon a software model (extrinsic evidence) by a TREX employee based upon a prior art patent drawing.

“A party seeking to establish that particular claims are invalid must overcome the presumption of validity in 35 U.S.C. § 282 by clear and convincing evidence.” State Contracting & Eng’g Corp. v. Condotte Am., Inc., 346 F.3d 1057, 1067 (Fed. Cir. 2003). A patent is invalid as anticipated if every limitation in a claim is found in a single prior art reference. Teleflex, 299 F.3d at 1335.

Nystrom argues that the district court erred by basing its invalidity determination not on the disclosure of the Zagelmeyer patent itself, but instead from renderings made by a TREX employee of hypothetical boards based on the perspective drawings in the Zagelmeyer patent. He argues this violates our precedent in Hockerson-Halberstadt that “patent drawings do not define the precise proportions of the elements and may not be relied on to show particular sizes if the specification is completely silent on the issue.” Hockerson-Halberstadt, 222 F.3d at 956 (citing In re Wright, 569 F.2d at 1127). Nystrom contends that the district court erred in relying on extrinsic evidence in invalidating the ’831 patent. The invalidity data relied on by the district court was generated by a TREX employee who made a software model of the boards depicted in the perspective drawings of Figure 3 of Zagelmeyer patent, then performed computations on the modeled boards to come up with the allegedly invalidating curvature to width ratio.

The district court erred in not properly applying the principles set forth in our prior precedents that arguments based on drawings not explicitly made to scale in issued patents are unavailing. Hockerson-Halberstadt indicated our disfavor in reading precise proportions into patent drawings which do not expressly provide such proportions....