Claims Invalidated Due to Lack of Sufficient Written Description and Strict Reading of Specification

Section 112 requires that the claims of a patent are sufficiently supported in the patent’s written description, which includes the specification and drawings. A recent Federal Circuit decision queries what subject matter an inventor possessed beyond the literal patent disclosure and how a skilled artisan’s knowledge at the time of the invention may impact this issue.

Holding

In Columbia Insurance Company v. Simpson Strong-Tie Company Inc., 2021-2145, 2021-2157 (Fed. Cir. Mar. 31, 2023), the United States Court of Appeals for the Federal Circuit (“Federal Circuit”) affirmed the Patent Trial and Appeal Board (“the Board”) decision finding original claims 1–19 and substitute claims 21–39 of U.S. Patent No. 10,316,510 (“’510 patent”) invalid for a lack of written description support.

Background

The ’510 patent is directed toward a truss hanger used to connect support beams to wall frames in modern buildings. The hanger extends through the sheathing and uses a channel-shaped portion to hold the support beam and an extension portion to define space for the sheathing.

The claims are drafted to require an extension portion that:

spac[es] the side panels from the back flange plane by a distance sized large enough to permit two layers of ⅝ inch thick sheathing to be received between the rear edge plane and the back flange plane, but too small to permit three layers of ⅝ inch thick sheathing to be received between the rear edge plane and the back flange plane.

’510 patent, 12:30–36 (emphasis added).

The Board found the claim to cover a range of sizes for the extension portion, including a lower bound (large enough to fit two layers of 5/8-inch-thick sheathing), an upper bound (too small to fit three layers of 5/8-inch-thick sheathing), and encompassing all sizes in between.

However, the Board determined that the specification only disclosed an extension portion sized to fit exactly two layers of 5/8-inch drywall and that “a skilled artisan would not consider [such] disclosure … to show possession of the claimed range.” Thus, the Board found the claim invalid because the written description failed to support the range of sizes claimed for the extension portion.

Federal Circuit Decision

Petitioner Columbia appealed, arguing that the Board (i) misinterpreted the claim as covering a range of extension portion sizes and (ii) improperly applied chemical arts cases involving unpredictable technologies to the simple mechanical claims at issue. The Federal Circuit rejected both arguments and affirmed the Board decision.

For the first argument, Columbia contended that the claims did not cover a range of sizes, but instead simply required the size of the extension portion to fit “exactly” two ⅝-inch layers of sheathing, which would require some extra room for installation. However, the Majority disagreed, finding that the language of the claim clearly set an upper limit of just under three ⅝-inch layers of sheathing, which is large enough to include more than the two layers disclosed in the specification.

For the second argument, the Majority conceded that a more predictable technology may allow a skilled artisan to “reasonably discern [certain] disclosures” more readily, but rejected that such principle provided a basis for reversal given that the same legal standard applies regardless. And the Majority found that substantial evidence supported the Board’s factual findings that person of ordinary skill in the art would not have reasonably discerned the claimed range based on the limited disclosure of just requiring two ⅝-inch layers of sheathing.  

Dissent

Judge Moore dissented, asserting that the claims met the written description requirement and criticizing the Majority for requiring too explicit of a disclosure of the claimed upper bound. Instead, Judge Moore made three points and determined that there was no reasonable basis to conclude that the inventor did not possess the claimed range of sizes, given the figures, understanding of a skilled artisan, and the simple and predictable technology at issue.

First, according to Judge Moore, the figures sufficiently showed the claimed range for the extension portion size. For example, nearly every figure in the patent displayed claimed sheathing having space large enough for two 5/8” sheets of drywall but not large enough for three, thus providing support for the claims that require at least two 5/8” layers of sheathing but not permitting enough space for three full layers.

Second, Judge Moore found that the evidence of record demonstrated that a skilled artisan would understand that the spacing described in the ’510 patent cannot be limited to precisely two layers but must incorporate some additional “tolerance,” as is typical in the mechanical engineering field, to ensure materials of a certain thickness comfortably fit into a space. Therefore, according to Judge Moore, the inventor of the ’510 patent possessed what was known to a person of skill in the art at the time of the invention, which included extension portions greater than the described two-layer thickness of sheathing to account for well-understood tolerances that ensure the material would fit.

Third, Judge Moore opined that the simple and predictable nature of the technology at issue further showed that the written description requirement was satisfied. The claim was directed to the dimensions required for a construction hanger to accommodate two 5/8"-thick sheets of drywall, which Judge Moore distinguished from chemical cases that present more unpredictable technologies, such as new combinations of chemical compounds. She shared the Majority’s view that unpredictable technologies require a higher level of disclosure to prove what an inventor possessed. Thus, Judge Moore was persuaded that because the claims covered a predictable mechanical processes, they warranted a finding that the inventor possessed more than the literal disclosure of the two-layer spacing, including that the spacing may be sized within the claimed range.

Takeaways

Practitioners in all technology areas should be mindful of drafting patent claims that are commensurate in scope with the examples and guidance provided in the specification, regardless of whether the technology is predictable or unpredictable.