Indefiniteness Affirmed: Patent Claims and the Danger of “About”

The case involved Enviro Tech’s U.S. Patent No. 10,912,321 (’321 Patent), which claims methods for treating poultry carcasses with a solution of peracetic acid in water. Representative claim 1 required “altering the pH of the peracetic acid-containing water to a pH of about 7.6 to about 10 by adding an alkaline source.” Safe Foods challenged the asserted claims as indefinite during claim construction, and the district court agreed, finding both the terms “about” and “an antimicrobial amount” indefinite. On appeal, the Federal Circuit affirmed the district court’s decision based on “about” alone, finding it unnecessary to determine whether “an antimicrobial amount” was also indefinite.

Specification and Prosecution History Fell Short
The Court noted that “words like ‘about’ and ‘approximately’ may be appropriately used to ‘avoid[] a strict numerical boundary to the specified parameter.’” However, the Court stated that when “a word of approximation is used, however, the parameter’s range must be reasonably certain based on the ‘technological facts of the particular case.’”

In this case, the parties agreed that the term “about” should be given its ordinary meaning of “approximately.” However, the Court found that “‘approximately’ provide[d] no more guidance on the permissible deviation of the claimed range.” The Court looked that the ’312 Patent specification and prosecution history. While the specification recited numerous experiments, the majority provided a variance of 0.3 or less from the target pH. For the examples that deviated more than 0.3, adjustments were made to alter the pH to be closer to the target before taking the next steps. However, the Court found that there were enough examples of experiments, including the larges sample size experiment, which deviated from the 0.3 target variance that a skilled artisan would not have had certainty that the term “about” meant a variance of 0.3.

The prosecution history provided no clarity because the use of the term “about” was inconsistent, indicating it was material to some claims but not to others.

Prior Art Made Precision Critical to Validity
The court noted that an “important determinant in our decision” was due to the fact that the claims were amended to avoid prior art. The specification of the ’312 Patent recites a pH of 6–10, while the prior art recited 7.0. “The prior art is almost ‘about’ a pH of 7.6.” In this situation, “the definiteness requirement of § 112 necessitates much more clarity than using the vague term ‘about.’”

Conclusion
This decision is a reminder about definiteness issues and approximation terms, assessing the entire record to determine whether a person of ordinary skill would be informed of the scope of the claim.