By Kevin E. Noonan –

While the Supreme Court established a rather definitive standard (“reasonable certainty by a person having ordinary skill in the art”) for determining indefiniteness under 35 U.S.C. § 112(b) in Nautilus, Inc. v. Biosig Instruments, Inc., and indefiniteness is a question of law mandating less deference by the Federal Circuit, the issue has arisen again in Enviro Tech Chemical Services, Inc. v. Safe Foods Corp.

The litigation relates to U.S. Patent No. 10,912,321 (“the ‘321 patent”) that is directed to “[m]ethods for treating poultry during processing for increasing the weight of the poultry,” using “peracetic acid,” according to the opinion; claim 1 of the ‘321 patent is reproduced in the opinion as being representative:

1.  A method of treating at least a portion of a poultry carcass with peracetic acid, said method comprising the steps of:

providing, in a reservoir, a peracetic acid-containing water, wherein the peracetic acid-containing water comprises water and an antimicrobial amount of a solution of peracetic acid;

after the step of providing the peracetic acid-containing water, determining the pH of the peracetic acid-containing water, and altering the pH of the peracetic acid-containing water to a pH of about 7.6 to about 10 by adding an alkaline source;

after the step of determining the pH and altering the pH of the peracetic acid-containing water, placing into the peracetic acid-containing water at least a portion of a poultry carcass;

after the step of placing at least the portion of the poultry carcass into the peracetic acid-containing water, determining the pH of the peracetic acid containing water in the reservoir with at least the portion of the poultry carcass therein, and altering the pH of the peracetic acid containing water to a pH of about 7.6 to about 10 by adding an alkaline source; and

after the step of determining the pH and altering the pH of the peracetic acid-containing water having at least the portion of the poultry carcass therein, removing at least the portion of the poultry carcass from the peracetic acid-containing water.

Defendant Safe Foods convinced the District Court that the terms “an antimicrobial amount” and “about” were indefinite, and this appeal followed.

The Federal Circuit affirmed, in an opinion by Judge Lourie joined by Judge Prost and District Judge Burroughs,* addressing the “about” limitation alone.  The panel specifically affirmed the District Court’s conclusion that neither the “the claims, specification, [nor] prosecution history,” i.e., the totality of the intrinsic evidence “inform[ed] a skilled artisan as to the scope of the term ‘about’ with reasonable certainty” and thus was indefinite.  While that determination could have been dispositive, relying as it does on the standard set forth by the Supreme Court in Nautilus, Inc. v. Biosig Instruments, Inc., the opinion fleshes out its jurisprudence (that has so far withstood negative Supreme Court review) by citing a number of its own cases.  These cases stand for the propositions that “words like ‘about’ and ‘approximately’ may be appropriately used to ‘avoid[] a strict numerical boundary to the specified parameter,’” OrthoMcNeil Pharm., Inc. v. Caraco Pharm. Lab’ys, Ltd., 476 F.3d 1321, 1326 (Fed. Cir. 2007) (quoting Pall Corp. v. Micron Separations, Inc., 66 F.3d 1211, 1217 (Fed. Cir. 1995)); and “[t]erms of degree, like ‘about’ and ‘approximately,’ are not inherently definite or indefinite,” citing Amgen, Inc. v. Chugai Pharm. Co., 927 F.2d 1200, 1218 (Fed. Cir. 1991).  However, these considerations are bounded by the requirement that “[w]hen a word of approximation is used, . . . the parameter’s range must be reasonably certain based on the ‘technological facts of the particular case,” under Ortho-McNeil, 476 F.3d at 1326 (quoting Pall, 66 F.3d at 1217); and Amgen, 927 F.2d at 1218.

The opinion then dissects the claims, specification, and prosecution history in search of disclosure regarding the definiteness or lack thereof of the term “about.”**  The claims do not recite any guidance relating to how much below the limits of pH 7.6 to pH 10 the word “about” modifies, the opinion asserts; substituting “approximately” for “about” provides no additional clarity.  Nor is there any disclosure in the specification that provides any “reasonable certainty” for the definition of the term; the best that could be gleaned would depend on the restriction of the variability for large number of experiments disclosed but even there “[in the] majority of the experiments, Enviro Tech proceeded only when the difference of the actual pH was less than or equal to 0.3 of the target pH.” In what the Court perceives as being a “particularly informative” example (due to the large number of chickens involved and recitation of the “goal” of the claims as being to “increase . . . a processing plant’s percent yield”) the disclosed experimental variation (of up to 0.35 to 0.5 of the target pH) provides “conflicting guidance” when compared with the consistent 0.3 variance in the majority examples.  Finally, in the prosecution history, Enviro Tech inconsistently argued inter alia non-obviousness with regard to specific limitations (“pH 7.6”) or the more flexible version thereof (“about [pH] 8 to about [pH] 9”).  The totality of the inconsistent use of the word “about” with regard to pH informed the Court that the term was “material to some claims and immaterial to others,” supporting indefiniteness according to Infinity Comput. Prods., Inc. v. Oki Data Ams., Inc., 987 F.3d 1053, 1059 (Fed. Cir. 2021).  And Enviro Tech’s arguments that its behavior during prosecution surrendered claim scope fell on deaf judicial ears based on those consistent inconsistencies and lack of simple declarative sentences providing the Office with the construction Enviro Tech now asserts.

Finally, the panel notes that claim 1 was amended to avoid certain prior art (having a pH of 7.0), which requires “much more clarity [to achieve?] than the vague term ‘about.’”

* Honorable Allison D. Burroughs, District Judge, U.S. District Court for the District of Massachusetts, sitting by designation.

** A short perusal of the use of the word “about” in the ‘321 patent (specification, claims, and abstract) discloses 241 uses of the word, none of which is associated with an express definition.

*** A broader review of indefiniteness relating to the term “about” can be found in Claim Construction and the Federal Circuit (The Intellectual Property Law Association of Chicago Litigation Committee, Noonan, KE, and Kelly, AG, eds.), West Publishing Co., 2024, Chapter 7.2 including:

• General Hospital v. Sienna Biopharmaceuticals, 888 F.3d 1368 (Fed. Cir. 2018), construed based on express disclosure of range of nanoparticle sized

• Allergan v. Sandoz, 796 F.3d 1293 (Fed. Cir. 2015), construed “about pH 7.3” to encompass variations of no more than one decimal place based on disclosure of a range of pH 6.8-7.2

• In re Cyclobenzoprine Hydrochloride Extended-Release Capsule Patent Litigation, 676 F.3d 1063 (Fed. Cir. 2012), reversed a construction wherein the claim limitation “about 125%” of a reference Cmax value was found to be infringed by an accused article having 129.5% of the reference in the absence of specification support

• Fering B.V. v. Watson Laboratories, 764 F.3d 1382 (Fed. Cir. 2014), held that, without additional disclosure in the specification the term “about” had an “ordinary and accepted” meaning of “approximately” as that term and the scope thereof would be understood by the skilled worker in the art.

Enviro Tech Chemical Services, Inc. v. Safe Foods Corp. (Fed. Cir. 2026)
Panel: Circuit Judges Lourie and Prost and District Judge Burroughs
Opinion by Circuit Judge Lourie