October 14, 2016

Disavowal By Description, Disparagement, and Argument Limit Claims

By Bryan K. Wheelock, Principal

In Poly America, LP v. API Industries, Inc., [2016-1200] (October 14, 2016), the Federal Circuit affirmed the district court’s construction of “short seal” in the claims of U.S. Patent No. 8,702,308 to require that such seals extend inwardly, because of clear and unequivocal statements that the inventor intended to limit the claimed invention.

Poly-America argues that in construing the term “short seal” to require inward extension, the district court erred by importing limitations from embodiments described in the specification, misreading the prosecution history, and ignoring principles of claim differentiation.  The Federal Circuit disagreed.

Claim construction departs from the plain and ordinary meaning in only two instances: (1) when a patentee acts as his own lexicographer; and (2) when the patentee disavows the full scope of the claim term in the specification or during prosecution.  There was no indication or assertion of lexicography in this case, so the only question remaining was whether the inventor disavowed trash bags with short seals that do not extend inwardly.  The Federal Circuit noted that disavowal can be effectuated by language in the specification or the prosecution history, but in either case, the standard for disavowal is exacting, requiring clear and unequivocal evidence that the claimed invention includes or does not include a particular feature.  However, while disavowal must be clear and unequivocal, it need not be explicit.

The Federal Circuit noted the short seal was described as “one of the characteristics of the present invention,” and that the specification disparaged prior art without the claimed feature. Furthermore, the Federal Circuit found that Poly-America’s reply to the rejection of all claims also contains a clear and unmistakable disavowal of short seals that do not extend inwardly.

The Federal Circuit said that this analysis did not involve importing limitations from embodiments described in the specification, noting that every embodiment described in the specification has inwardly extended short seals and every section of the specification indicates the importance of inwardly extended short seals.