Selected Aspects Of The Impact Of Patent Application Drafting And Prosecution


Louis S. Sorell, Patent Counsel at Google Inc. in New York City, sent in this article he wrote discussing issues that arise during patent prosectuon which may impact subsequent litigation.  Sorell will be speaking at PLI’s Fundamentals of Patent Prosecution 2011: A Boot Camp for Claim Drafting & Amendment Writing on June 17, 2011.  The following is an excerpt from the article:


Issues often arise during patent prosecution which impact the course of subsequent patent litigation.  This paper discusses several specific areas in which decisions made during prosecution may particularly impact subsequent litigation.

Claim Construction Issues

A.   Background

With respect to the claim language itself, the words of the claims govern and are generally given their ordinary and customary meaning. The focus of this analysis is “what one of ordinary skill in the art at the time of the invention would have understood the term to mean.”

However, there are situations in which a claim term may be given a definition other than what one of ordinary skill in the art would give it. An inventor is entitled to be his or her own lexicographer; thus, where it is apparent from the patent and prosecution history that the inventor intended a meaning different from that understood by one ordinarily skilled in the art, the inventor’s meaning governs.

Other claims in a patent can also be a valuable source of enlightenment as to the meaning of a claim term. Thus, for example, the presence of a dependent claim that adds a particular limitation gives rise to a presumption that the limitation in question is not present in the independent claim. This is because, under the doctrine of claim differentiation, claims of a patent are presumed to have different scopes, particularly as between independent and dependent claims. While the doctrine of claim differentiation provides a presumption that the claims in a patent have different scopes, it is “not a hard and fast rule of construction.” In particular, “the doctrine of claim differentiation can not broaden claims beyond their correct scope, determined in light of the specification and the prosecution history and any relevant extrinsic evidence.”

Although it is impermissible to import limitations from the preferred embodiments described in the specifications into a claim, a claim term should not normally be interpreted in such a manner as to exclude a preferred embodiment.

The patent specification is always relevant to claim construction, because pursuant to 35 U.S.C. § 112, ¶ 1, it is the specification that must provide a written description of the invention in such full, clear and exact terms as to allow a person of ordinary skill in the art to make and use the invention. Thus, “a claim must be read in view of the specification of which it is part.” Usually, the patent specification is the single best guide to the meaning of a disputed term.17 However, it is impermissible to read a limitation from the specification into a claim, except in the case of claims reciting means-plus-function or step-plus-function limitations governed by 35 U.S.C. § 112, ¶ 6.

The prosecution history of a patent is also important for claim construction, because “it may contain contemporaneous exchanges between the patent applicant and the PTO about what the claims mean.” Arguments and amendments made during the prosecution of a patent application … as well as the specification and other claims must be examined to determine the meaning of terms in a claim.” Moreover, statements made in the prosecution history may modify the ordinary meaning of a claim term.21 A court may also consider the prior art cited in the prosecution history, which may contain clues as to what the claims do not cover.

If the claim language remains genuinely ambiguous after consideration of the intrinsic evidence, reliance upon extrinsic evidence to construe the claims is appropriate, but only to the extent that such reliance does not “contradict the claim construction unambiguously apparent from the intrinsic evidence.” In addition, extrinsic sources which may be used include dictionaries, treatises and encyclopedias.24 However, the use of such extrinsic sources to interpret claims must be done with caution, because “the resulting definitions … do not necessarily reflect the inventor’s goal of distinctly setting forth his invention as a person of ordinary skill in that particular art would understand it.” In addition, opinion testimony, “whether by an attorney or artisan in the field of technology to which the patent is directed … should be treated with utmost caution, for it is no better than opinion testimony on the meaning of statutory terms.”












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