August 5, 2022by Matthew Barnet

In Ex parte Whiteman (Appeal No. 2021-003736), the examiner rejected the claims as obvious based on a hypothetical particle distribution consistent with the prior art. The PTAB reversed.

Independent claim 1 recited:

An inorganic particulate material comprising:

equal to or more than about 3 ppm of particles having a particle size equal to or greater than about 25 μm,

equal to or less than about 40 wt% of particles smaller than about 0.75 μm,

having a d98 less than about 11 μm, and

wherein the % of particles smaller than 0.5 μm is equal to or less than about 25 wt%.

Relevant to the appeal, the italicized limitations required that (i) particles smaller than about 0.75 μm made up no more than about 40 wt% of the particle distribution, and (ii) particles smaller than 0.5 μm made up no more than about 25 wt% of the particle distribution. In other words, there could not be a large fraction of very small particles. For example, a distribution in which 50 wt% of particles were smaller than 0.75 μm would be outside the scope of the claims, as would a distribution in which 30 wt% of particles were smaller than 0.5 μm.

The examiner rejected claim 1 as obvious over a single reference (Calhoun). The examiner relied on a d50 value (rather than wt%) in the range of 0.8 to 3 μm in Calhoun. A d50 value of 0.8 μm, for example, would mean that 50% of the particles were smaller than 0.8 μm. The examiner took the position that the d50 value in Calhoun “impl[ied] or at least suggest[ed] that the claimed wt% of <~0.75μm particles is met.” The examiner found that it would have been obvious “to adjust the particles’ size (either by removing undesirably-sized particles and/or agglomerates, grinding too large particles/agglomerates, and/or agglomerating too small particles)…to meet the claimed wt% of <~0.75μm particles.”

The applicant argued that although Calhoun described a d50 value in the range of 0.8 to 3 μm, the reference said nothing about the fraction of particles smaller than 0.75 μm, or smaller than 0.5 μm, as recited in claim 1. The applicant argued that the examiner had created “a convoluted hypothetical” particle distribution from Calhoun, in which a d50 value of 0.8 μm could be satisfied by 40 wt% of the particles being smaller than 0.75 μm (according to claim 1), and 10 wt% of the particles being between 0.75 and 0.80 μm. Although such a hypothetical particle distribution might have been consistent with the d50 value in Calhoun, the applicant argued that this hypothetical particle distribution was in no way disclosed or suggested by Calhoun.

The PTAB sided with the applicant. The PTAB found that Calhoun’s d50 value of 0.8 to 3 μm “neither discloses nor suggests anything about the particular percentage of particles smaller than about 0.75 μm or smaller than 0.5 μm.” The PTAB found that the “[e]xaminer assumes without providing sufficient evidence that Calhoun’s preferred particulate product having a d50 of 0.8-3 μm contains ‘smaller portion[s] within’ the product, which meet the claimed particular product size distributions.” Accordingly, the PTAB reversed the obviousness rejection.

Takeaway: Obviousness cannot be based on speculation. If a U.S. examiner finds a claimed feature to be obvious over prior art describing a somewhat related, but different feature, the examiner must provide supporting evidence instead of mere speculation. If, as in Ex parte Whiteman, the examiner speculates about a “convoluted hypothetical” feature that is consistent with the prior art – but is not disclosed or suggested by the prior art – it is worth challenging the examiner’s position.

Judges: Colaianni, Dennett, McGee

by Matthew Barnet

Matthew E. Barnet, Ph.D., is a patent attorney and partner at Element IP. His practice focuses on patent procurement and client counseling, including expertise in validity and infringement opinions.