PTAB Overturns Examiner’s Obviousness Rejection based on Reference Disclosing “Overlapping” Range

The USPTO Patent Trial and Appeal Board recently overturned an Examiner’s obviousness rejection of a claim disclosing a specific ratio, where the cited reference disclosed a range that encompassed the claimed ratio.

The rejected claim recites:

1. An oral care composition, comprising:
   a soluble zinc citrate and sodium hexametaphosphate, and water;
   wherein the relative amounts of zinc citrate and sodium hexametaphosphate provide the soluble zinc polyphosphate complex with a phosphorus to zinc mole ratio of 20:1.[1]

The PTAB acknowledged that the cited reference, Glandorf, “reasonably suggests a composition comprising (a) water, and (b) a soluble zinc polyphosphate complex, wherein (i) the soluble zinc polyphosphate complex is made by combining zinc citrate and sodium hexametaphosphate.”[2]
The PTAB also acknowledged that Glandorf further discloses “the range of phosphates to be about 6 to about 125.” Nevertheless, the PTAB concluded that the Examiner [fails] to appreciate [that] the claimed invention requires the soluble zinc polyphosphate complex . . . to have a specific phosphorous to zinc mole ratio, 20:1, and simply identifying a disclosure of polyphosphates that may comprise 6-125 phosphates in Glandorf fails to make obvious [the] claimed phosphorus to zinc mole ratio.[3]

The reasoning behind the PTAB’s reversal may be useful to prosecutors with similar rejections. Quoting from the Appellant’s brief, the opinion states that the Examiner did not demonstrate why one of skill in the art would have made a zinc polyphosphate complex with the specific ratio[4]. The opinion further quotes from case law stating that “[r]ejections on obviousness grounds cannot be sustained by mere conclusory statements; instead, there must be some articulated reasoning with some rational underpinning to support the legal conclusion of obviousness.”[5]

This decision demonstrates the importance of not only arguing that the Examiner demonstrate that the claimed invention is disclosed in the cited references, but also arguing that they must provide a specific and rational reason why one of skill in the art would have arrived at the claimed invention.

[1] Ex parte Shiri Nawrocki et al., Appeal 2021-005499 (PTAB December 7, 2022)
[2] Id. at 9
[3] Id. at 11.
[4] Id. (internal citations omitted)
[5] Id. (emphasis in original).