Beware the Object of the Invention
One thing that can be good when working as a lawyer is to have a way with words. As a patent prosecutor, you must also be very careful with your words.
It is well known that prosecution history estoppel can be used to limit the scope of patent claims. A recent decision from the Middle District of New Carolina also reminds prosecutors of the need to have caution in drafting a patent’s specification.
In BASF Agro B.V., Arnhem (NL), Wädenswil Branch, et. al. v. Makhteshim Agan of North America, Inc., et. al., the accused infringer (Makhteshim) argued that the patentee (Kimura, who assigned his patent rights to BASF) disclaimed claim coverage over Makhteshim’s method of applying insecticide. Interestingly, Makhteshim argued that the disclaimer was in a single sentence of the patent’s specification (U.S. Pat. No. 6,414,040), in which the patentee described the objects of the invention.
In its decision finding noninfringement, the court agreed.
The court stated (at pp. 18-19):
The use of an exterior barrier as a required element of treatment is prior art as defined and clearly disclaimed by Mr. Kimura. Under Northern Telecom, because Mr. Kimura clearly and unmistakably disclaimed the use of a prior art barrier, the prior art barrier and Mr. Kimura’s invention became “mutually exclusive.” See Northern Telecom Ltd., 215 F.3d at 1297. Thus, by definition, one practicing a form of treatment which requires both an exterior barrier element and an interior loophole element is not practicing Mr. Kimura’s invention. This court finds that Mr. Kimura’s description of his invention as “a termite treatment without barrier,” (U.S. Pat. No. 6,414,040, col. 1, ll. 43-44), excludes barrier treatments from the invention and therefore the combination of a barrier treatment and Mr. Kimura’s loopholes does not infringe the patents at issue.
The entirety of Kimura’s disclaimer read: “Another object of the instant invention is to provide a termite treatment without barrier,” with the key word being without. The court found this to be a clear disclaimer of claim scope, and contrasted this disclaimer to cases where the patentee was either silent on the issue, or stated that certain features were merely undesirable, in which cases courts do not find disclaimers of claim scope.