Although there is a statutory requirement that claims use definite language (35 U.S.C. 112(b)), words of degree such as those listed above are often tolerated because they are "as precise as the subject matter permits." See Hybritech Inc. v. Monoclonal Antibodies, Inc., 802 F.2d 1367, 1385 (Fed. Cir. 1986). For example, In Rosemount, Inc. v. Beckman Instruments, Inc., 727 F.2d at 1547, 1540 (Fed. Cir. 1984) the patent claims described a device for measuring pH, having one component "in close proximity" to another. The court found that "close proximity" was a term routinely used and understood in the industry, so the definiteness of the claim was upheld.
There are several times, however, when a court will treat words of degree with suspicion. This is especially true when the patentee argues that the term is broad enough to encompass the accused product yet narrow enough to avoid the prior art, and provides no guidance as where the line in-between should be. In Augen, Inc. v. Chugai Pharmaceuticals Co., 927 F.2d 1200 (Fed. Cir. 1991) the court held the term "about" was insufficiently definite in the context of the particular patent being challenged. In this case, the patent claimed a specific activity of "at least about 160,000 IU/AU", the prior art exhibited a specific activity of 128,620 IU/AU, but the applicant provided absolutely no hint whatsoever as to whether the allegedly infringing activity of 145,000 IU/AU would come within the scope of the claims.
There are several times, however, when a court will treat words of degree with suspicion. This is especially true when the patentee argues that the term is broad enough to encompass the accused product yet narrow enough to avoid the prior art, and provides no guidance as where the line in-between should be. In Augen, Inc. v. Chugai Pharmaceuticals Co., 927 F.2d 1200 (Fed. Cir. 1991) the court held the term "about" was insufficiently definite in the context of the particular patent being challenged. In this case, the patent claimed a specific activity of "at least about 160,000 IU/AU", the prior art exhibited a specific activity of 128,620 IU/AU, but the applicant provided absolutely no hint whatsoever as to whether the allegedly infringing activity of 145,000 IU/AU would come within the scope of the claims.