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Justin E. Gray

IP Litigation Attorney at Foley & Lardner LLP

Former Adjunct Professor at Northwestern University School of Law

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Federal Circuit Affirms Broad Disclaimer of Subject Matter During Prosecution

BASF Agro B.V., Arnhem (NL), Wadenswil Branch v. Makhteshim Agan of North America, Inc. (Fed. Cir. Mar. 20, 2013) (nonprecedential)

In this case, the Federal Circuit affirmed a district court's claim construction that the patentee had disclaimed particular scope during prosecution.  The patents at issue related to methods of applying insecticide to protect buildings against termites.

The district court had determined that during prosecution the patentee had "disclaimed applying insecticide without loopholes around a building, and applying insecticide without loopholes under a building, respectively."  On appeal, the plaintiff argued this disclaimer was too broad, and while the patents teach a treatment "without barrier", the disclaimer should have been limited to "without loopholes both around and under a building."

The Federal Circuit found that the district court correctly construed the claims of the patents based on the determination that the patentee had disclaimed "barrier treatments" without loopholes.  Looking first to the claim language itself, the Federal Circuit stated that "[t]he claims unambiguously require areas that are treated and untreated."  Looking next to the specification, the Federal Circuit determined that language in the specification describing the prior art and the object of the invention "confirms that the claims do not cover the prior art's loophole-free barrier treatments."  Turning to the prosecution history, the Federal Circuit explained that the patentee made specific arguments to distinguish prior art that required "the formation of a barrier that has no untreated locations" and the patentee relied on a declaration that also distinguished the prior art for that same reason and found the patented method was "unobvious and surprising."

Plaintiff made the argument that the patents' use of the term "comprising" overcame the potential disavowal of subject matter, but the Federal Circuit disagreed, stating that "comprising" is not "a talismanic incantation that counteracts a clear disclaimer."

Plaintiff also presented expert testimony that at the time of the invention an ordinarily skilled artisan would have understood barrier treatments to require formation of a complete barrier both around a building and underneath its foundation.  The Federal Circuit disregarded that testimony as inconsistent with the intrinsic evidence, explaining that "[e]ven testimony from a qualified expert has little probative value if it is inconsistent with the intrinsic record."

The Federal Circuit therefore affirmed the district court's claim construction.