On May 4, 2026, the U.S. Court of Appeals for the Federal Circuit held that certain patent claims were invalid because they used the term “about” without clearly defining its scope. The Court found that the claims did not provide enough guidance to show what range was actually covered.

The Court explained that terms like “about” are not automatically problematic, but they must be supported by clear and consistent boundaries in the patent’s specification or prosecution history. Without that clarity, claims may be found indefinite, especially when they are close to prior art. The decision highlights the need for careful drafting when using approximate terms in patent claims. While such terms are allowed, they should be tied to clear definitions, ranges, or tolerances in the record. The Court also emphasized the importance of consistency throughout the patent. Inconsistent examples or shifting use of terms during prosecution can create uncertainty and undermine claim definiteness.

Read the Cantor Colburn client alert for an analysis of the situation and what it might mean for you.

This alert was prepared by Cantor Colburn Partner Michael H. Brodowski, Ph.D., Todd Garabedian, Ph.D., and Jeffrey Waters, with contributions from David Kincaid.