In Enviro Tech Chemical v. Safe Foods Corp., 2022 WL 17721179 (E.D. Ark. Dec. 15, 2022), the Eastern District of Arkansas construed disputed terms in their Markman Order for U.S. Patent No. 10,912,321 (“the ’321 patent”), which discloses a “method of treating . . . poultry carcass with peracetic acid” to prevent spoilage and contamination during poultry processing.
On the path from “farm to table” in poultry production, the chicken moves from the farm to the processing facility, where the carcass is treated and prepared for consumption, and finally to the distributor for retail sale. During processing, poultry meat must be carefully handled and stored in a “chill tank” to prevent contamination and spoilage. Enviro Tech’s ’321 patent claims a method for treating the poultry in the chill tank with peracetic acid to prevent microorganism growth, such as “Salmonella, Campylobacter, yeast, and molds.” Id. at *1.
Independent claim 1 read:
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.
Id. at *3 (emphasis in opinion).
In the Markman Order, the district court construed five disputed claim terms: (1) “determining the pH,” (2) “altering the pH,” (3) “after the step of,” (4) “about,” and (5) “antimicrobial amount.” The district court discerned the “ordinary and customary meaning of the claim terms,” by looking first at the claims themselves, the context of the specification, and then at the prosecution history and accepted extrinsic evidence. Id. at *5.
1. “determining the pH”
Claim 1 of the ’321 patent requires “determining the pH” of the peracetic acid-containing water. Plaintiff asserted that “determining” encompasses its plain and ordinary meaning, while Defendant asserted a narrower construction, arguing that “determining” means “measuring.” Id. at *6. The court discussed how an estimation of the pH could fall within Plaintiff’s broader construction, but in light of the claims and specification, the narrower construction is more appropriate. Id. at *7. The court noted the dependent claims rely on a pH measurement in claim 1, and that Plaintiff had disclosed embodiments and examples with specific pH measurements. Id. As such, “determining the pH” was construed to mean “measuring the pH.”
2. “altering the pH”
With respect to “altering the pH of the peracetic acid-containing water”, there was a dispute on whether altering meant merely raising the pH or if the term encompassed both raising and lowering the pH. Id. at *8. The ’321 patent claimed “adding an alkaline source” if the pH was “outside of a specified range.” The court construed the “altering” step as limited to just raising. Id. at *10. “[T]he step of “altering the pH ... by adding an alkaline source” is performed by raising the pH of the peracetic acid-containing water from outside to inside of the specified range.” Id.
3. “after the step of”
The ’321 patent is a method patent comprising a series of steps, and the parties disputed whether “after the step” required the method patent to be performed in sequential order. Id. Plaintiff astated the dependent claims can be performed through “continuous processes” or “intervening steps” out of claim order. The court construed “after the step of” to mean after the previous step, and the method steps must be performed in order to fall within the scope (or potentially infringe) the ’321 patent. Id. at *12. “[T]he Patent is clear. Each recited step of the
independent claims, except the first, requires performance of the previous recited step to have occurred. That construction is perfectly compatible with the dependent claims and does not foreclose continuous processes or unrecited intervening steps.” Id.
4. Indefinite Terms
Defendant alleged that “about” modifying the recited pH range and “antimicrobial amount” were indefinite. Plaintiff asserted that “about” refers to the “outer boundaries of the specified pH ranges.” The court noted, however, that “about” refers to a “term of degree” that lacks a numerical range, resulting in an ambiguous and indefinite term. Id. at *13. The court looked to both the specification and prosecution history and did not find any instance where Plaintiff divulged “reasonable certainty” of what a numerical degree for “about” could be. Id. at *16. As such, “about” was an indefinite term.
With respect to “antimicrobial amount,” the court found a similar indefiniteness problem. Id. at *18. The claim itself defines “antimicrobial to mean a solution that “eradicate[d] or reduce[d]” spoilage by microorganisms.” Unfortunately, neither the claims nor the prosecution history indicated what the potential range of the “antimicrobial amount” might be to reduce microorganism activity. Id. at *17.
Parties drafting method patent claims should be cautious of transition language between steps. Here, Plaintiff’s patent scope was narrowed, requiring a party to follow the exact order of procedural steps in the ’321 patent before they could infringe. See also, Amgen, Inc. v. Sandoz, Inc., 923 F.3d 1023 (Fed. Cir. 2019) (multiple steps were separate and required in order so Sandoz’s one-step process did not infringe). Don’t leave it up for interpretation – draft the claims and specification with the objective of obtaining the desired claim construction.
Caution is always required when using relative terms. Using words of degree arise may raise questions regarding whether a person of ordinary skill in the art could understand with “reasonable certainty” how the recited claim would be infringed. Under the Supreme Court standard from Nautilus, Inc. v. Biosig Instruments, Inc., 572 U.S. 898, 901 (2014), a claim must inform one of ordinary skill in the art with “reasonable certainty” as to the scope of the claim. This allows one of ordinary skill in the art to determine whether a product or activity is infringing. Words such as “about” must be treated as carefully as technical terms of art. See also M.P.E.P. § 2173.02(II). Clearly, an ounce of prevention in drafting may be worth many, many pounds of cure. Claim language choice at the drafting stage is a key for future enforcement of a patent. Consider developing and including in the specification a definition for the term. Further, during prosecution or litigation, an expert declaration may help explain how one of ordinary skill in the art would have understood a term. Compare the outcome in Enviro to that in Niazi Licensing Corp. v. St. Jude Med. S.C., Inc., No. 21-1864 (Fed. Cir. Apr. 11, 2022), where the Federal Circuit held that the claim terms could be understood with reasonable certainty though they were broad. See https://www.finnegan.com/en/insights/blogs/prosecution-first/relative-terms-sufficient-for-reasonable-certainty.html