Evidence of narrow patent claim scope in specification outweighs claim differentiation arguments in claim construction.

At trial, a jury found that certain patentee’s claims relating to retractable syringes were infringed.  The Federal Circuit reversed, holding that the district court erred in construing the term “body” too broadly by failing to limit it to a “one-piece body.”

The majority opinion, authored by Judge Lourie, held that evidence from the specification compelled a narrow construction of the claimed “body” as restricted to a one-piece structure.  The court recognized that a broad reading was supported by the presence of a dependent claim identifying a “one-piece body” alongside an independent claim reciting only a “body.”  Such claim differentiation arguments will be outweighed, however, by evidence from the written description or prosecution history dictating a contrary construction.  Here, the characterization of prior art, summary of the invention, and specific embodiments found in the specification all indicated that the claimed “body” referred only to a one-piece body.

Judge Plager wrote a separate concurrence to emphasize a “fundamental point” that claims cannot go beyond the scope of the actual invention that entitles the inventor to a patent.  Accordingly, the written description is the “heart” of the patent and should largely drive claim construction because it defines what the inventor actually invented.

Chief Judge Rader dissented, opining that the language of the claims made it clear that the term “body” was not limited to one piece and that the majority improperly imported limitations from the specification into the claims.  Instead, the specification can only trump the plain language of the claims when it gives a term a special, technical meaning, or when it contains an intentional disclaimer or disavowal of claim scope by the inventor.

A copy of the opinion can be found here.