Let’s Talk “About”. . . That Bird?

Why It Matters

Indefinite claim language can render a patent unenforceable, jeopardizing IP protection for food‑tech and biotech innovations. The ruling signals to drafters that vague terms like “about” must be anchored to a defined range to survive legal scrutiny.

Key Takeaways

• "About" deemed indefinite for pH 7.6‑10 in poultry patent
• Experiments showed 0.3‑0.5 pH deviation, no fixed tolerance
• Prosecution history offered no clarification after claim amendment
• Federal Circuit applied Nautilus, requiring reasonable certainty
• Decision warns drafters to define approximation ranges precisely

Pulse Analysis

The term “about” has long been a gray area in patent drafting, often slipping between casual approximation and legal certainty. Courts apply the Nautilus test to determine whether a claim term provides a person of ordinary skill in the art with enough precision to define the invention’s scope. When a word of approximation is used, the specification, experimental data, and prosecution history must collectively narrow the possible range; otherwise, the claim risks being labeled indefinite under 35 U.S.C. § 112.

In the recent Enviro Tech Chemical Services case, the Federal Circuit dissected a claim that required adjusting a peracetic‑acid solution to a “pH of about 7.6 to about 10.” The patent’s own experiments alternated between a strict 0.3‑unit deviation and broader tolerances up to 0.5 units, offering no consistent benchmark. Moreover, the applicant’s arguments during amendment—shifting the lower bound from 7.3 to 7.6—failed to clarify the intended leeway. The court concluded that, without a reasonably certain parameter, the term “about” rendered the claim indefinite.

For practitioners, the ruling is a cautionary tale. Drafting teams must anchor any approximate language to explicit ranges, whether through precise numerical limits, defined percentages, or clear functional boundaries. Industries reliant on process patents—such as food processing, chemicals, and biotech—should audit existing portfolios for vague terms that could be vulnerable. By integrating concrete tolerances early, companies protect their patents from invalidation and preserve the commercial value of their innovations.