© 2003, Gallagher & Dawsey Co., LPA
Those familiar with the patent application process recognize that
patent attorneys use phrases such as "substantially" and
"approximately" all too often. In fact, some patent applications could
be reduced in length by several pages simply by removing such phrases.
However, such expressions are used to avoid strict numerical
boundaries that may result in narrow patent protection. The question
often presented is whether phrases such as "substantially" and
"approximately" satisfy the requirement of 35 USC §112 that the
applicant "particularly point out and distinctly claim" the invention.
The Court of Appeals for the Federal Circuit (CAFC) recently held, in
Verve, LLC v. Crane Cams, Inc., that such language is permissible when
warranted by the nature of the invention. The CAFC found that the
lower court erred in requiring that the intrinsic evidence of the
specification and prosecution history is the sole source of meaning of
words that are used in a technologic context. The CAFC stated that
determination of the meaning of such words is that as would be
understood by persons in the field of the invention. In other words,
an applicant need not explicitly state in the body of the patent
application that the terms "substantially" or "about" mean plus, or
minus, so many units.
The controversy in Verve centered on a claim for an internal
combustion engine push rod that is hollow and defined as having a
"substantially constant wall thickness." The lower court recognized
that the usage of "substantially" may be adequately definite in some
cases, but ruled that it was indefinite in this case because it was
not further defined in the application. The CAFC vacated the lower
court finding of indefiniteness based upon the "understanding of
persons in the field" logic expressed above. The CAFC reasoned that
since patent documents are written for persons familiar with the
relevant field, the patentee is not required to include information in
the specification that is readily understood by such persons.
Therefore, patent attorneys may continue in their exaggerated use of
"substantially" and "approximately" in patent applications, provided
it is warranted by the nature of the invention, with reduced fears of
later having a finding of indefiniteness used against their client.