Product by process claims can result in a burden on applicant to come forward with evidence that prior art showing the apparently identical product by another process is indeed distinct. Specifically, “where a product-by-process claim is rejected over a prior art product that appears to be identical, although produced by a different process, the burden is upon the applicants to come forward with evidence establishing an unobvious difference between the claimed product and the prior art product.” In re Marosi, 710 F.2d 799, 803 (Fed. Cir. 1983).

Today we see an example of this applied to a Dyson invention related to rare earth magnets. Claim 14 of Dyson’s application on appeal is reproduced below. Appeal 2023-000542 Application 15/742,460

Claim 14: A magnet comprising a magnetic body and one or more beads of dysprosium metal; wherein the magnetic body has a surface and contains grains of rare earth magnet alloy, and wherein each bead is deposited onto a part of the surface via a cold spray process.

One way for an applicant to provide evidence in support of its position that the prior art process would produce a different product is to cite to the specification. Dyson cited to its specification in arguing that cold spraying (the process disclosed in the specification) resulted in distinct structure as compared to that of the prior art (which allegedly used generic spraying and in paricular heating before spraying).

However, whether or not Dyson’s evidence supported the idea that cold spraying could achieve the claimed structure, it did not establish that the prior art' process could not. From the PTAB’s decision (emphasis added):

Appellant has not met its burden. Appellant does not present evidence to support the contention that cold spray deposition uniquely results in adiabatic shear bands.

While, from a technical point of view, Dyson may be correct to argue that cold spraying yields metal particles exhibiting adiabatic shear bands that would not have been obtained if the material were heated prior to spraying spec evidence. The problem was the Dyson had mere attorney arguments in this regard and the specification, while not inconsistent with the argument, did not sufficiently establish the facts that Dyson was now asserting.

So, remember that when carrying the burden, evidence is needed that supports the facts asserted. And while the specification can constitute evidence, it must do more than be consistent with an assertion.