Product-by-process Claims: Definite? Indefinite?

A product-by-process claim is a product claim that defines the claimed product in terms of the process by which it is made.  A product-by-process claim is proper and should not be rejected under 35 U.S.C. § 112(b) or pre-AIA 35 U.S.C. § 112, second paragraph, as indefinite, as long as it is clear that the claim is directed to a product.

On July 20, 2020, the Patent Trial and Appeal Board (“Board”) scrutinized a product-by-process claim and reversed the Examiner’s indefiniteness rejection in Ex parte Castellana (Appeal No. 2019-006605).  The claim read as follows:

104.   A product for treating the skin and mucous membranes selected from a cream, an ointment, a liquid, a gel, and an aerosol, wherein the product is prepared by:

mixing a suitable quantity of trichloroacetic acid with a composition of hydrogen peroxide (H₂O₂) to form a first mixture, wherein the trichloroacetic acid in the first mixture is in a concentration of 30% to 35% w/w and the composition of hydrogen peroxide in the first mixture is present in a concentration of about 50% to about 85%[;]

providing a determinate quantity of basic compound to buffer the first mixture to obtain a pH value of between 2.3 and 2.6 of the first mixture; and

adding the basic compound to the first mixture in order to buffer the first mixture,

wherein the buffered first mixture is a product.

The Examiner found that the claim was directed to a product defined by product-by-process limitations of an intermediate to be incorporated into the final product and that the claim did not define the components or their weight percentages in the product.  The Examiner concluded “one of ordinary skill in the art would not be reasonably apprised of the scope of the invention” and thus rejected the claim under § 112, second paragraph, as indefinite.

Appellant contended “the [claim is] definite as the process recited therein clearly and precisely informs persons skilled in the art of the boundaries of [the] protected subject matter.”  Appellant further argued the product at issue was a “buffered first mixture.”

The Board noted that a claim must satisfy two requirements to be definite under § 112, second paragraph: first, it must set forth what “the applicant regards as his invention;” and second, it must do so “with sufficient particularity and distinctness, i.e., the claim must be sufficiently ‘definite.’”  Since the patentability of a product-by-process claim depends on the product itself, the Board reviewed the claim to identify what was the product at issue.

The Board found claim 104 recited a product prepared by the steps of (1) mixing trichloroacetic acid and H₂O₂, and (2) adding basic compound to buffer the first mixture, thereby forming a buffered first mixture.  That is, the claimed process steps resulted in a buffered first mixture, which was the product at issue as argued by Appellant.  Therefore, the Board found Appellant’s arguments were persuasive and held that the claim identified the buffered first mixture as the product prepared by the claimed process with sufficient particularity and distinctness, satisfying the two requirements under § 112, second paragraph.  However, the Board noted that although the claim was found definite, the duplicate recitation of “a product” in “wherein the buffered first mixture is a product” in addition to the same recitation in the preamble did not improve the clarity.  The Board indicated that “wherein the buffered first mixture is the product” (emphasis added) would be preferred.

Takeaway:  Sometimes, using product-by-process limitations may be the only way to define a product or to distinguish a product from prior art.  In such situations, in order to satisfy the definiteness requirements, it is advisable to introduce a more specific term (such as “the buffered first mixture” in this case) into the claim language to refer to the product.  Using a phrase such as “thereby forming/obtaining …” to explicitly identify the resulted product by the process steps could also be helpful.

Judges:  J. N. Fredman, D. Katz, and J. G. New