PTAB Reverses for Lack of Reasonable Expectation of Success

A conclusion of obviousness requires that a skilled artisan would have had a reason to combine the teachings of the prior art references to achieve the claimed invention, and that the skilled artisan would have had a reasonable expectation of success from doing so.

The reasonable expectation of success requirement can be difficult to challenge during prosecution because the reply is consistently that “only a reasonable expectation of success, not absolute predictability, is necessary for a conclusion of obviousness.” In re Longi, 759 F.2d 887, 897 (Fed. Cir. 1985). This seemingly insurmountable conclusion is compounded by a lack of bright-line rules defining when a reasonable expectation of success exists. However, Ex parte Saerens provides a nice example of facts resulting in a conclusion that a skilled artisan would not have had a reasonable expectation of success. Appeal No. 2020-005386 (PTAB Feb. 25, 2021) (non-precedential).

The claims in Saerens were drawn to a method for fermenting cocoa beans with at least one Pichia kluyveri yeast strain, where the fermented cocoa beans exhibited particular ratios of isobutyl acetate/isobutanol and isoamyl acetate/isoamyl alcohol.

The Examiner relied on a primary reference for its disclosure of adding pectinolytic yeast during cocoa bean fermentation and cited a secondary reference for evidence that certain strains of Pichia kluyveri are pectinolytic. According to the Examiner, a skilled artisan would have had a reason to select Pichia kluyveri from the secondary reference for use as the pectinolytic yeast in the primary reference.

The Appellant disagreed because the secondary reference “focused on examination of pectinolytic activity on a coffee substrate, not cocoa” and there was no evidence the Pichia kluyveri would have exhibited similar activity on all pectin-containing substrates, or would otherwise have been useful for cocoa bean fermentation. In response, the Examiner argued that “pectinolytic activity is universal,” and predictably stated that “Appellants are reminded that only a ‘reasonable expectation of success’, not an ‘absolute success’ would have been required in an obviousness rejection.” Examiner’s Answer at 15.

Reversing the Examiner’s rejection, the Board held that “the prior art must give some indication of which parameters were critical or which of many possible choices is likely to be successful.” Here, however, the secondary reference relied on by the Examiner showed significantly different Pichia kluyveri activity when cultured on yeast polygalacturonic acid medium vs. coffee broth. Consequently, the evidence of record showed that Pichia kluyveri activity would have been considered substrate-specific in complete contradiction to the Examiner’s unsubstantiated finding that “pectinolytic activity is universal,” irrespective of whether the substrate is coffee or cocoa.

Accordingly, the Board found that a skilled artisan would not have been guided by the secondary reference to substitute Pichia kluyveri for any of the yeasts in the primary reference, and reversed the Examiner’s rejection.

Takeaway: It can be difficult to persuade an Examiner who has already concluded there would have been a reasonable expectation of success even when the subject matter claimed is unpredictable, as with the chemical and biological arts. This is illustrated in Saerens, where the Examiner maintained the obviousness rejection despite the experimental data in the secondary reference itself contradicting his conclusion of “universal activity.” Nevertheless, it is important to present any experimental data, technical publications, and/or expert testimony that shows unpredictability as these will be more persuasive than mere attorney argument. In the event that an Examiner is not persuaded by such evidence, the evidence can serve as a basis for reversal in a formal appeal.

Judges: C. Timm, G. Best, J. Snay