Imagine That IP Law Blog

In an Inter Partes Review (IPR), one of the arguments that a patent owner can raise against petitioner’s argument for unpatentability based on obviousness is that the asserted prior art is not analogous art.  According to the Federal Circuit, “[t]wo separate tests define the scope of analogous prior art: (1) whether the art is from the same field of endeavor, regardless of the problem addressed, and, (2) if the reference is not within the field of the inventor’s endeavor, whether the reference still is reasonably pertinent to the particular problem with which the inventor is involved.”  Sanofi-Aventis Deutschland GmbH v. Mylan Pharm. Inc., 66 F.4th 1373, 1377 (Fed. Cir. 2023).  “The identification of analogous prior art is a factual question.”  In re Bigio, 381 F.3d 1320, 1324 (Fed. Cir. 2004) (citing In re GPAC, 57 F.3d 1573, 1577 (Fed. Cir. 1995)).

Specifically, the first test for analogous art “requires the PTO to determine the appropriate field of endeavor by reference to explanations of the invention’s subject matter in the patent application, including the embodiments, function, and structure of the claimed invention.”  In re Bigio, 371 F.3d at 1325.  In that case, the cited prior art discloses a toothbrush, whereas the patent application at issue claims a hair brush.  Id. at 1323.  The Board “broadly construed ‘hair brush’ to encompass ‘not only brushes that may be used for human hair on [a] scalp, but also brushes that may be used for hairs on other parts of animal bodies (e.g. human facial hair, human eyebrow hair, or pet hair),’” and “determined that toothbrushes fell within Bigio’s field of endeavor and therefore constituted analogous art.”  Id. at 1323-24.

The Federal Circuit agreed with the Board and rejected the patent applicant’s argument that “the ‘field of endeavor’ test for analogous art is unworkable because the lack of clear guidelines leaves the application of this test to an examiner’s subjective judgment.”  Id. at 1325.  Finding that the Board’s determination was based on substantial evidence, the Federal Circuit emphasized that “this court has previously ‘reminded . . . the PTO that it is necessary to consider ‘the reality of the circumstances’ - in other words, common sense - in deciding in which fields a person of ordinary skill would reasonably be expected to look for a solution to the problem facing the inventor.”  Id. at 1326 (quoting In re Oetiker, 977 F.2d 1443, 1447 (Fed. Cir. 1992) (quoting In re Wood, 599 F.2d 1032, 1036 (CCPA 1979)) (italics in original).

If the prior art is not within the field of the inventor’s endeavor, then the second test for analogous art is “whether the reference still is reasonably pertinent to the particular problem with which the inventor is involved.”  Sanofi-Aventis Deutschland GmbH, 66 F.4th at 1377.  “A ‘reasonably pertinent’ reference is one that an ordinarily skilled artisan would reasonably have consulted in seeking a solution to the problem that the inventor was attempting to solve.” Airbus S.A.S. v. Firepass Corp., 941 F.3d 1374, 1382 (Fed. Cir. 2019).  Accordingly, “a reference is reasonably pertinent if . . . it is one which, because of the matter with which it deals, logically would have commended itself to an inventor’s attention in considering his problem.”  Sci. Plastic Prods. v. Biotage AB, 766 F.3d 1355, 1359 (Fed. Cir. 2014).

To determine if the reference would have commended itself to an inventor’s attention, “[t]he problems to which the claimed invention and reference at issue relate must be identified and compared from the perspective of a person having ordinary skill in the art (‘PHOSITA’).”  Donner Tech., LLC v. Pro Stage Gear, LLC, 979 F.3d 1353, 1360 (Fed. Cir. 2020).  “The analogous art inquiry is a factual one, requiring inquiry into the similarities of the problems and the closeness of the subject matter as viewed by a person of ordinary skill.”  Sci. Plastic Prods., 766 F.3d at 1360.  Thus, if the prior art and the invention are not within the same field of endeavor, the second test hinges upon the closeness of the subject matter and the similarities (or differences) between the problems solved by the prior art and by the invention as viewed by a person of ordinary skill in the art.