The Changing Meaning of Patent Claim Terms

The claims of a patent are central to virtually every aspect of patent law. The claims define the scope of the invention, and their meaning therefore determines both whether a defendant’s product infringes a patent and whether the patent is valid. One of the most significant aspects of patent litigation is “claim construction,” the process of defining the words of the claim in other, theoretically clearer words. Courts construe the claims of the patent by starting with the plain meaning of their terms as they would be understood by a person having ordinary skill in the art, or PHOSITA. Claim construction occurs in every patent case during a “Markman hearing.” Indeed, claim construction is so important to patent litigation that once the court construes the claims, most patent cases settle, and those that do not are often decided on summary judgment. As Judge Rich succinctly put it, “the name of the game is the claim.”