Obviousness Rejections Based On Inherent Properties Require Evidence

November 4, 2019 – Article

Ex parte Wong (PTAB October 21, 2019) (Appeal No. Appeal 2019-001384, in Application Serial No. 13/800,317) (before Ankenbrand, Praiss, and Snay, APJ) (opinion by Ankenbrand, APJ)

In this board decision, the Examiner is reversed, with the decision highlighting the burden the Examiner must meet in rejecting a compound as obvious based on assumed inherent properties.

The invention is focused on hydrous zirconium oxide (“HZO”) particles that comprise an oxygen-containing additive. Importantly, the HZO particles are also described in the claims as having a sulfate adsorption capacity of 10 – 50 mg/g, a phosphate binding capacity of 0.1 – 10 mg/g, and certain surface areas and particles sizes. With these binding capacities, and the oxygen-containing additive to modulate particle solubility, the HZO particles may be dispersed in a solution as a sorbent material.

In the final action, the Examiner rejected the claims as obvious over compounds taught in US 2006/0140840 A1 (Wong ‘840), US 2002/0112609 A1 (Wong ‘609), and US 7,252,767 B2 (Bortun). Wong ‘840 describes a sorbent material of particles comprising zirconium phosphate and an oxygen-containing additive. Wong ‘609 describes a sorbent material of zirconium phosphate and HZO. Thus, the Examiner used these two references to teach particles comprising HZO and an oxygen-containing additive. The Examiner then used Bortun to teach HZO with the sulfate adsorption capacity, phosphate binding capacity, surface area, and particle size of the inventive HZO particles. Bortun reads on the binding capacity of phosphate but mentions resistance against poisoning by sulfate, without specific details about the amount of sulfate that may actually adsorb. Despite this deficiency, the Examiner relied on Bortun to make an odd argument that the high phosphate binding capacity would “result in a low adsorption capacity for sulfate,” to prove that the present invention’s sulfate adsorption capacity of 10 – 50 mg/g is an obvious characteristic of the HZO particles.

The counter-argument proffered by the Appellant was that the zirconium phosphate of Wong ‘840 is unrelated to the HZO particles. Regarding the “low” 10 – 50 mg/g sulfate adsorption capacity, this adsorption capacity is actually greater than that of other HZO compounds, and the Appellant further pointed to their experimental evidence of an unexpected 10 – 22 mg/g adsorption capacity. The Appellant further argued that Bortun teaches away from using HZO to adsorb sulfate.

Interestingly, the Examiner argued inherency in two different ways. In the first, Bortun was used to read on the sulfate adsorption capacity being related to the phosphate binding capacity, in which one property of a compound is used to show that another property of the compound is inherent. In the second, the Examiner used Wong ‘840 to relate its soluble precursor to HZO particles, which is an example of arguing that separate compounds have inherently similar properties based on some other similar property, such as chemical composition.

The PTAB panel was not persuaded by the Examiner’s rationale and reversed the rejection. Most notably the PTAB panel agreed with the Appellant that the Examiner failed to provide sufficient evidence or reasoning of inherency.

The decision, drawing reference to KSR Int’l Co. v. Teleflex Inc., 550 U.S. 398, 418 (2007), shows that rejections based on inherency must be backed by sufficient evidence and cannot be presumed just because certain properties may seem likely. Indeed, as most patent practitioners know, inherency requires necessity—not probabilities—and the burden of establishing a prima facie basis of inherency resides initially with the USPTO, at least during prosecution.