Claims definite unless “insolubly ambiguous.”

PatentlyOImage043Marley Mouldings v. Mikron Industries (Fed. Cir. 2005).

At summary judgment, the district court (N.D.Ill.) found Marley’s patent invalid for indefiniteness.  On appeal, the Court of Appeals for the Federal Circuit (CAFC) reversed, holding that the claims were not “insolubly ambiguous” and thus not indefinite under 35 U.S.C. 112.

Marley’s patent is directed to a method of forming a foam composite as a wood replacement.  The claims specify the volume of various materials use to create the composite.  The district court found the volume requirements to be indefinite because the specification did not include any means to calculate the percent volume — “a critical determination to discerning” infringement.

Mikron also argued that “measurement of components by weight, not by volume, is the standard practice in the field of polymer processing, and [thus,]that the patentee’s failure to conform to this practice is further support for the indefiniteness of the claims.”

The CAFC disagreed, finding that “non-conformity is not of itself indefiniteness.”

We conclude that the district court erred in law, in requiring that the specification describe the relationship between volume and weight of the wood filler used or usable in the process. When a claim “is not insolubly ambiguous, it is not invalid for indefiniteness.” (quoting Bancorp Servs, 359 F.3d 1367).



  • This case attempts to distinguish Honeywell v. ITC, 341 F.3d 1332, 1339-40 (Fed. Cir. 2003) (claim indefinite because yarn melting parameter included without stating which of four known methods of preparing and testing the yarn should be used).

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