Enviro Tech Chemical Services, Inc. v. Safe Foods Corp.

Enviro Tech Chemical Services, Inc. v. Safe Foods Corp. The term 'about' as used in the pH range limitation ('about 7.6 to about 10') of the '321 patent is indefinite under § 112(b) because the claims, specification, and prosecution history collectively fail to inform a skilled artisan of the term's scope with reasonable certainty. All asserted claims are therefore invalid. This precedential decision reinforces that 'about' and similar approximation terms are not inherently definite—when a patent's specification contains conflicting examples and prosecution history treats the term inconsistently, particularly where the claimed range was amended to clear prior art that sits close to the range boundary, the term will fail the Nautilus reasonable-certainty standard. Affirmed The '321 patent claims a method of treating poultry carcasses with peracetic acid at a pH of 'about 7.6 to about 10'; the court found this range indefinite because neither the claims nor the specification established how far below 7.6 or above 10 the pH could deviate. The specification was internally inconsistent: most experiments proceeded only when pH deviated ≤0.3 from target, but several—including a large commercial-scale trial involving 5.8 million chickens—proceeded with deviations of 0.35–0.5, undermining any fixed meaning for 'about.' Prosecution history compounded the problem: Enviro Tech argued patentability in one response without using 'about' (treating the lower bound as exactly 7.6) and in the very next page used 'about' for a different claim range, never explaining what the term means. Enviro Tech's argument that amending the lower bound from 'about 7.3' to 'about 7.6' implicitly disclaimed deviations greater than 0.3 was rejected because the amendment was unaccompanied by explanatory remarks defining 'about,' as required under Personalized Media. The court emphasized that because the prior art reached as close as pH 7.0 and the specification disclosed pHs of 6–10, the proximity of prior art to the claimed range made clarity especially critical—the prior art was, as the court noted, almost 'about' a pH of 7.6. § 112(b) claim construction precedential § 112(b) claim construction precedential § 112(b) claim construction precedential