If you are considering initiating a patent infringement lawsuit, or getting ready to defend against one, you will hear the term "claim chart."

A claim chart is a tool to evaluate potential patent infringement. It is a tool used by attorneys representing a patent owner considering the possibility of filing suit against an infringer. It is also used by attorneys representing an alleged patent infringer. A typical claim chart might have the following format:

Claim 1 Infringing Product A tool for turning a screw, comprising: Picture of overall infringing product a handle; and Picture of handle of infringing product a blade attached to the handle Picture of blade of infringing product

The claim chart might include all claims of the patent, or perhaps just the independent claims. It may only include a representative claim when there are many claims in the patent.

The claim chart breaks down a single claim by its individual claim elements. For each claim element, information (such as a picture from an advertisement) about the infringing product is obtained that establishes (or not establishes) that the infringing product has the claim element. For infringement to exist, all elements in a given claim must be found in the infringing product.

For example, in the above sample chart, the claim requires that a blade be attached to a handle. Opposite to that claim element in the chart, the picture of the infringing blade may or may not show the blade attached to the handle. If not attached, one may conclude there is no infringement. If it is attached, one may conclude there is infringement.

What the claim chart seeks to accomplish is avoiding the hasty conclusions by a patent owner that "it's obvious the product infringes" or by the alleged infringer that "it's obvious our product is different from the patent owner's product." The claim chart puts the question of infringement in "black and white" terms and enables the question to be answered in a systematic fashion.

But the claim chart is only as good as the details in it. Some claim charts are prepared without all of the claim language in the chart. If not all of the claim language is present, one cannot accurately assess the presence or absence of infringement.

Another deficiency that can exist in a claim chart is when the claim elements are described in one long paragraph so that details in the claim elements become obscured. As an example, the above sample claim may have been written in a single sentence — "a handle and a blade attached to the handle." In a situation where the claim might have several hundreds of words, individual words can be overlooked, though they might be significant to the question of infringement.

Attorneys for patent owners and alleged infringers may also want claim charts to meet their ethical and legal obligations. Attorneys have an obligation to avoid asserting claims or defenses in the absence of a good faith belief that the claim or defense is supported by the facts and law. Claim charts enable attorneys to meet that obligation.

PRACTICE POINTER: While a patent owner or alleged infringer might be in a rush, or may be reluctant to spend the money on claim charts, they are a useful tool to evaluate the strength or weakness of one's position. As such, claim charts can help avoid expenses if one's position is determined to be weak. They can help just incurring expenses when one's position is determined to be strong.

© Michael A. Shimokaji, 2014 The contents of this article represent the opinions of the author and not those of the author's law firm or clients.

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