Claims construction is considered one of the most important stages of a patent infringement lawsuit. The purpose of claims construction is to determine the meaning of key words or terms used in a patent’s claims, because infringement allegations will be measured against those claims.
All patents include “claims,” which are an element-by-element description of the invention. The claims disclosed in the patent are often described as the “metes and bounds” of the patent. If the device accused of infringing the patent falls inside those metes and bounds, you have infringement. If not, there is no infringement. And often, whether the accused device falls within those ‘metes and bounds’ depends upon the definitions given to key words or terms in the patent. Defining what the key word or term means is referred to as “claims construction,” and is often the subject of a special hearing, referred to as a Markman hearing.
For example, suppose the Empire in the Star Wars universe had a patent on the Death Star that described an “internal powered weapon.” Does that description mean the weapon is inside the Death Star, or that the weapon’s power source is inside the Death Star? Or both? Suppose that years later, the First Order builds its own planet killer, Star Killer, which mounts a planet killing weapon inside the hull. And suppose that weapon draws its power from a star? If the weapon is inside the hull, but the power source is not, has Star Killer in fact infringed the Death Star patent? Such a determination could well depend upon the outcome of a Markman hearing, where the judge would determine whether “internal powered weapon,” as used in the Death Star patent, meant both the power source and the weapon were inside the hull, or only that the weapon had to be inside the hull.
How do courts determine the meaning of those few key words or phrases? Courts first look to the patent itself to determine the meaning of a term. Did, for example, the Empire define the words “internal powered weapon” in the Death Star Patent? If somewhere in the patent the inventor defined those words to mean the weapon’s power source was inside the hull, that is how the term will be construed, and the First Order may be off the hook for infringement. On the other hand, if the inventor defined the term to mean only the weapon had to be inside the hull, the First Order may be an infringer. But suppose the inventor did not define those words anywhere in the patent? The court would look to those parts of the patent that describe the invention’s background, give a detailed description of the invention, and provide examples of how to practice (use or build) the invention, to glean the meaning of “internal powered weapon.” If, for example, one description of ways to build the weapon describes using an external power source, then the court could eventually conclude the First Order’s Star Killer does infringe on the Empire’s Death Star Patent.
Sometimes, however, even the detailed descriptions and examples, referred to as the “specification,” offer no clues as to the meaning of a word or term the litigants or court believe to be important. In such cases, the court may look at the patent’s history at the U.S. Patent and Trademark Office (USPTO). A patent makes the journey from application to grant through a series of stages referred to a ‘patent prosecution.” Often, the inventor provides material to the USPTO during the prosecution. He may amend claims, or provide explanations in support of a claim, for example. What the inventor said about the invention or how he amended the claims sometimes reveals the meaning of a word or term.
All of the foregoing, the patent claims, drawings, and specification, and the patent prosecution history, are referred to as ‘intrinsic evidence.’ When that is not enough, courts move on to ‘extrinsic evidence,’ meaning evidence not found in the patent itself, or in the prosecution history. Such evidence can include dictionary definitions, professional and trade publications, and testimony. Generally, however, courts prefer not to rely on extrinsic evidence.
The outcome of the Markman hearing may determine the outcome of a patent infringement case. In the example above, if the court concludes that claims recited in the Empire’s Death Star patent did not include use of a weapon powered by a source of energy outside the Star Killer’s hull, the First Order would be in a strong position to seek a summary judgment finding there was no infringement, or negotiate a settlement very favorable to it. On the other hand, if the claims construction goes against the First Order, in that the court concludes that both internal and external power sources are included within the ‘metes and bounds’ of the Empire’s Death Star patent, the First Order could find itself the object of an injunction enjoining it from continuing the use the Star Killer as a tool of oppression, while paying hefty monetary damages to the Empire.