Are terms of “degree” indefinite claim language under 35 U.S.C. 112?

Written by Mark Terry

Terms of degree – such as “easily,” “readily,” and “aesthetically pleasing” – can be subjective and therefore problematic when used as claim language. But the recent Federal Circuit decision of Hearing Components, Inc. v. Shure Inc., 600 F. 3d 1357 (Fed. Cir. 2010) provides some guidelines on how to properly use terms of degree in claim language without worrying about a 35 U.S.C. §112 indefiniteness rejection. As a Florida Patent Attorney, I write claims almost every day, so this case is topical for me.

Under 35 U.S.C. § 112, second paragraph, the “specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention,” which is known as the definiteness requirement. “Claims are considered indefinite when they are not amenable to construction or are insolubly ambiguous. Thus, the definiteness of claim terms depends on whether those terms can be given any reasonable meaning. Id. Indefiniteness requires a determination whether those skilled in the art would understand what is claimed.” Young v. Lumenis, Inc., 492 F.3d 1336, 1344, 1346 (Fed.Cir. 2007). The purpose of the definiteness requirement is to ensure that “the claims, as interpreted in view of the written description, adequately perform their function of notifying the public of the scope of the patentee’s right to exclude.” Honeywell Int’l, Inc. v. Int’l Trade Comm’n, 341 F.3d 1332, 1339 (Fed.Cir. 2003).

“[A] patentee need not define his invention with mathematical precision in order to comply with the definiteness requirement.” Invitrogen Corp. v. Biocrest Mfg., L.P., 424 F.3d 1374, 1384 (Fed.Cir.2005) (quotation marks omitted). Not all terms of degree are indefinite. However, the specification must “provide[ ] some standard for measuring that degree.” Datamize, LLC v. Plumtree Software, Inc., 417 F.3d 1342, 1351 (Fed.Cir.2005) (quotation marks omitted). In Hearing Components, the CAFC held that although the claim term “readily” does not refer to a mathematical measure of degree, in Datamize, the CAFC addressed the “purely subjective” claim term “aesthetically pleasing” and stated that, as with terms of degree, “a court must determine whether the patent’s specification supplies some standard for measuring the scope of the phrase. Thus, we next consult the written description.” Datamize, LLC v. Plumtree Software, Inc.

Lessons Learned: The moral of the story here is that you can indeed use terms of degree in claim language, as long as you explain how to measure that term in the specification. For example, if you use the claim term “easily connected,” you could state in the specification that this term refers to connecting two elements manually, such as a snap-fit system, without the use of tools or other mechanical devices.


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