Supreme Court to Settle Disputed Rule of Claim Construction

From the March 2002 Intellectual Property Issue

The first step in assessing the possible infringement of a patent is to construe the claims- at-issue. The claims of a patent define the metes and bounds of the patent`s exclusionary rights, much like the description in a real estate deed. A claim is infringed if a device or method falls within the scope of the patent`s claim and “achieves substantially the same result by similar means and operations” as the patented device. Alternatively, if the device or method falls outside the scope of the patent`s claim, infringement may be avoided. As a result, the first step in determining whether a patent has been infringed is to construe the claim to determine its scope.

A claim may be construed in light of both intrinsic and extrinsic evidence. Intrinsic evidence includes things that occurred or were before the Patent and Trademark Office, such as the prosecution history of the patent`s claim, the prior art, and any admissions made by the patentee. Extrinsic evidence includes matters such as the understanding of a person skilled in the art and expert testimony.

After the claim has been construed, the next step is to determine whether it can be read onto the accused device or method. If the claim reads easily onto the device or method, and if the device or method “does substantially the same work in substantially the same way to achieve substantially the same result”, the claim is said to be literally infringed.

If the claim does not read easily onto the accused device or method, it must be further determined whether the device or method infringes under the doctrine of equivalents. The doctrine of equivalents is a judicially-created doctrine that seeks to prevent one from pirating an invention because of a scrivener`s mistake or omission. The doctrine recognizes that there is no common denominator of technical description. No two people use the same words to describe the same "thing". However, two "things" may, in fact, be the same, no matter how they are described.

In determining whether a patentee is entitled to resort to the doctrine of equivalents, courts have historically looked to the reasons for any changes to the claim that occurred during the prosecution of the patent. The doctrine of prosecution history estoppel operated to prevent a patentee from attempting to recapture through the doctrine of equivalents that which the patentee had surrendered during prosecution of the patent. However, in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Inc., the Federal Circuit recently decided that a narrowing amendment to a patent claim made for any reason related to the statutory requirements for patentability precludes the patentee from attempting to urge that the claim is entitled to a scope broader than its literal language. In other words, the Festo decision looks only at the fact of an amendment of a patent claim, rather than the reason for the amendment.

The Festo decision represents a change in how patent claims are construed. While Festo affords easy to understand rules, it has been argued that it may unintentionally narrow the scope of a patent claim.

The United States Supreme Court heard an appeal in the Festo case in January, and a decision is expected soon. Certainly, all practitioners hope that the Supreme Court`s decision will clarify and settle the rules as to how a claim is to be construed in light of narrowing amendments made during prosecution of the patent.

This article was prepared by Peter K. Sommer, an attorney in the firm`s Intellectual Property Group.
e-mail: psommer@phillipslytle.com