Federal Circuit IP

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

By Ziyu Ma Published June 10, 2026

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

CAFC No. 2024-2160, Decided May 4, 2026

(Lourie, Prost, Burroughs)

 

Background:  

  • Enviro Tech sued Safe Foods in the Eastern District of Arkansas, alleging infringement of claims 1–3, 5–12, 14–19, 21–24, 26–29, and 31–33 of U.S. Patent No. 10,912,321.  
  • The ’321 patent is directed to methods for treating poultry during processing to increase poultry weight, using peracetic acid-containing water.  
    • Representative claim 1 requires altering the pH of the peracetic acid-containing water to “a pH of about 7.6 to about 10” by adding an alkaline source, before and after placing a poultry carcass into the water.  
  • During claim construction, Safe Foods argued that the claim terms “an antimicrobial amount” and “about” were indefinite.  
  • The district court held both terms indefinite and entered judgment that the asserted claims were invalid. Enviro Tech appealed.  

Issue: whether the claim term “about,” as used in the pH range “about 7.6 to about 10,” informs a POSITA with reasonable certainty about the scope of the claimed invention under § 112(b). 

Holding: Affirmed.  

Federal Circuit Analysis: 

  • The Federal Circuit found that the intrinsic record did not provide a clear boundary for “about.” 
    • The specification contained inconsistent examples: some suggested a deviation of 0.3 pH units or less, while others suggested a broader deviation.  
    • The prosecution history also treated “about” inconsistently.  
  • That lack of clarity was especially problematic because the claimed pH range had been amended to avoid prior art with a pH as close as 7.0.  
    • Where prior art sits close to the claimed numerical range, the Court emphasized that § 112 requires greater clarity about the scope of approximation terms. 

Takeaways:  

  • For prosecutors: 
    • Define the tolerance for terms like “about” in the specification, especially when the claimed range is close to prior art.  
    • Keep examples consistent, or explain why different tolerances apply.  
    • During prosecution, avoid inconsistent treatment of approximation terms.  
  • For patent challengers:  
    • Compare the claim language, examples, and prosecution history for inconsistent treatment of “about” or similar terms, particularly where the numerical limitation was added to distinguish close prior art.