Destroying the Intended Purpose of a Reference May Not Be a ‘Golden Ticket’ to Patentability

A patent claim of invention is considered obvious, and thus unpatentable, in light of a combination of prior art references if a person of ordinary skill in the art (POSITA) would have had a reason, or motivation, to combine the references as recited in the claim. There are responses, or defenses, to such a finding of obviousness, including if the combination renders the reference unsatisfactory or inoperable for its intended purpose – also called “frustration of purpose.” See In re Fritch, 972 F.2d 1260, 1265 n.12 (Fed. Cir. 1992) (“A proposed modification [is] inappropriate for an obviousness inquiry when the modification render[s] the prior art reference inoperable for its intended purpose.”). Recent decisions by the Patent Trial and Appeal Board (PTAB) show the Board coming to different decisions on how to treat this defense. In Thermaltake Tech. Co. v. Chen, the Board found that even though the patent owner argued that the proposed modification of an electrical circuit would destroy the circuit’s transmission lines and render it inoperable. IPR2024-01230, Paper 51 (PTAB Feb. 17, 2026). In Deere & Co. v. David’s Dozer, the Board denied institution of the IPR because the proposed modification would render the primary reference, Funk, inoperable; specifically, the combination was “antithetical to Funk’s operation.” IPR2024-01442, Paper 7, p. 12 (PTAB Jan. 7, 2025).

Thus, the question remains how to balance these opposing positions when determining if the patent claim is indeed patentable.

Two Cases

There are two seminal cases where proposed modifications would have destroyed the intended purpose of the primary prior art and thus negated a finding of obviousness. In Cook Group Inc. v. Boston Sci. Scimed, Inc., the Patent Trial and Appeal Board (PTAB) found that combining biopsy forceps with another reference would result in loss of the forceps’ key functions: the ability to identify and excise tissue. The Board then determined that the modified forceps were inoperable for their intended purpose. The U.S. Court of Appeals for the Federal Circuit affirmed, emphasizing that an inference of nonobviousness is especially strong where the prior art’s teachings undermine the very reason proffered as to why an ordinary artisan would have combined the known elements. Similarly, in In re Gordon, the Federal Circuit reversed an obviousness determination where the modification inadvertently created a faulty gasoline filtration device where the gasoline to be filtered would be trapped at the top, while the water and heavier oils sought to be separated would flow out of the outlet instead of the purified gasoline, thus destroying the intended purpose of the primary reference.

No Golden Ticket

Loss of functionality or destroying the intended purpose of a reference is not, however, a “golden ticket” to overcoming a proposed obviousness rejection. The Federal Circuit has noted that the “loss of key functionality” in a prior art combination does not necessarily render the combination unsatisfactory for its intended purpose. Rather, the ordinary artisan would balance the prior art combination’s “advantages and disadvantages” when determining whether to combine the two references. Though each prior art combination is unique and requires a case-by-case analysis, the following Federal Circuit case provides insight.

In Allied Erecting & Dismantling Co. v. Genesis Attachments, LLC, which was an appeal from an inter partes review (IPR) proceeding, the patentee argued that combining the Caterpillar reference—which disclosed a demolition tool with quick-change functionality for replacing its demolition jaws—with the Ogawa reference would require substantial design and structural changes, ultimately rendering the Caterpillar reference inoperable. The petitioner and the Board, however, identified a particular benefit from the combination of references, specifically “a greater degree of movement between the jaws.”

The Federal Circuit agreed with the Board, finding that although the modification may “impede” Caterpillar’s quick-change functionality, there were also specific and obvious advantages to the proposed modification/combination. Specifically, the Court found that a skilled artisan could achieve a greater degree of movement between the demolition jaws without entirely eliminating the quick-change functionality, even if it required redesigning the Caterpillar reference.

Takeaways

There are at least two takeaways from these cases. The first is that if a combination of references destroys an intended purpose of the primary reference, such a finding suggests that the combination is nonobvious. The second is that the combination can still render the claim obvious if a POSITA would nonetheless recognize a benefit or advantage of the combination. Another important distinction among the cases is whether the combination destroys versus merely impedes the intended purpose of the primary reference. In Allied, the quick-change functionality was “impeded” but the device remained operational while gaining augmented grasping capabilities. In Cook and Gordon, the modifications would have rendered the devices “inoperable,” eliminating the ability to identify and excise tissue or trapping the very liquid designed to be purified.

It is this distinction between Allied and Cook/Gordon that petitioners and patent owners at the PTAB should center their arguments on. A petitioner relying on a modified reference, particularly where an inoperability argument is foreseeable, should identify not only a generic motivation to combine, but also the particular capability or performance improvement that a POSITA would have accepted despite the impeded functionality. The petitioner should also explain why the proposed modification does not destroy the core function of the reference, even if it alters or impedes some aspect of how that function is performed. Conversely, a patent owner invoking frustration of purpose should explain why the proposed modification crosses the line from an ordinary design tradeoff to a change that destroys the reference’s core operating principle. As in Cook and Gordon, a strong argument is to explain in detail why the petitioner’s modification destroys, rather than merely impedes, the function for which the primary reference was selected.

Thus, as is always the case, the facts of the proposed combination must be considered as a whole.

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Author: BigAlBaloo
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