Functional Equivalence Requires Similar Purpose 

The claims on appeal in Shooshtari were drawn to a binder composition that included “a catalyst for catalyzing a crosslinking reaction between the reducing sugar and the crosslinking agent, wherein the catalyst comprises a sulfonic acid compound.” The primary reference relied on by the Examiner disclosed a binder composition that included a pH adjuster, such as HCl, for preventing unwanted polymerization, but it did not disclose the presence of a sulfonic acid compound.

To remedy this deficiency the Examiner relied on a secondary reference that taught a binder composition containing a mineral acid catalyst, such as HCl or p-toluene sulfonic acid, to effect crosslinking reactions. According to the Examiner, it would have been obvious to replace the HCl pH adjuster of the primary reference with the sulfonic acid polymerization catalyst of the secondary reference. The Board disagreed.

In particular, the Board found that the primary reference taught HCl for the sole purpose of adjusting the pH to inhibit unwanted polymerization, while the secondary reference taught HCl and sulfonic acid as acid catalysts to effect crosslinking reactions–a completely different purpose. Consequently, the Board held the Examiner failed to identify a reason why a skilled artisan would have sought to include the acid catalyst of the secondary reference in the composition of the primary reference.

Takeaway: Shooshtari shows the value in analyzing the purpose of each component of a composition when facing an obviousness rejection that relies on functional equivalence. The purpose and function of the components ties into whether there is an apparent reason to modify the prior art in the manner proposed by the Examiner. Here, the purpose of the components in each of the references was contradictory to the other such that a skilled artisan would not have had a reason to equate and replace them. Accordingly, when facing a rejection that relies on functional equivalence it is important to fully assess the purpose and function of the components involved.

Judges: T. Ownes, W. Wilson, J. Snay

Equivalence is a common tool used by Examiners to demonstrate the obviousness of a claimed component that is known to be interchangeable with a component in the prior art. However, Ex parte Breder illustrates that the interchangeability alone is insufficient for obviousness – the context of the equivalence is key. Appeal No. 2021-002289 (PTAB Oct. 5, 2021) (non-precedential).

In Breder, the claims were directed to a method of antagonizing 5-HT7 and 5-HT1B receptor activity in a patient suffering from ADHD by administering viloxazine. The primary reference relied on by the Examiner taught a method of treating ADHD with a norepinephrine reuptake inhibitor reboxetine. The primary reference emphasized the high selectivity of reboxetine for norepinephrine processing and its efficacy for treating ADHD, but said nothing whatsoever about viloxazine.

Attempting to present a prima facie case of obviousness for the treatment of ADHD with viloxazine, the Examiner found a secondary reference that disclosed reboxetine and viloxazine as norepinephrine reuptake inhibitors and alleged that a skilled artisan “would have been motivated to substitute the norepinephrine reuptake inhibitor, viloxazine, … with the norepinephrine reuptake inhibitor, reboxetine, in the method of treating ADHD.” Despite this apparent equivalence, the Board did not agree.

From the Board’s perspective, any functional equivalence between viloxazine and reboxetine as norepinephrine reuptake inhibitors was outweighed by the secondary reference had nothing to do with ADHD. In fact, the secondary reference was directed to a topical composition for the transdermal delivery of active agents for ailments such as muscle pain and muscle cramps, which could optionally include norepinephrine reuptake inhibitors. According to the Board, the “sole nexus between the teaching of [the prior art]” is “that reboxetine and viloxazine are norepinephrine reuptake inhibitors,” and this was not enough.

Simply put, the Board did not agree that an optional ingredient in a topical composition for treating muscle pain provided sufficient motivation for a skilled artisan to replace the reboxetine with viloxazine in a complexly different method for treating ADHD, with a reasonable expectation of success. The primary reference’s emphasis on the high selectivity and efficacy of reboxetine bolstered this conclusion.

Takeaway: Context is key. Functional equivalence can be essential for a prima facie case when the primary reference lacks a claimed component but includes a component known to be interchangeable with it. But as shown by Breder, this functional equivalence will not carry the day when the references being combined have nothing in common. Therefore, it is important to thoroughly assess the purpose and end use of each of the references being combined when an Examiner relies on a theory of functional equivalence for the obviousness of a claimed component.

Judges: R. Lebovitz, J. New, D. Cotta