Patentee’s Lexicography Negates Infringement Despite Defendant’s Use of Claim Term in Product Literature

| Jeremy Anapol


Before Reyna, Newman, and Clevenger. Appeal from the U.S. District Court for the District of Delaware.

Summary: The patentee’s lexicography of “parison” excluded the allegedly infringing product even though the alleged infringer’s product literature specifically described a “parison.”

Plastic Omnium (“Omnium”) sued Donghee America and Donghee Alabama (“Donghee”) for patent infringement. The two patents at issue described a method of manufacturing plastic fuel tanks. In the district court, the parties disputed the construction of the term “parison.” Omnium argued that the patentee acted as its own lexicographer, so the plain meaning of the term “parison”—i.e., “a hollow plastic tube exiting the die of an extrusion head”—did not apply. The district court agreed and adopted a narrowing construction of “parison” as “referring to a plastic tube … that … is split either immediately upon exiting the die or at some point thereafter.” Donghee moved for summary judgment of noninfringement based on this narrowing construction. The court granted the motion, finding that the accused product splits the alleged “parison” inside the extrusion equipment rather than outside as the construction required.

The Federal Circuit held that the district court properly applied its narrowing claim construction to the accused product. Omnium disputed neither the construction nor the facts concerning the operation of the accused product. The Federal Circuit acknowledged that Donghee’s literature says the accused product includes a “parison,” but explained that “the patentee’s definition of ‘parison’ in the specification and as construed by the court—not Donghee’s product literature—controls whether the accused product falls within the scope of the claim.” Thus, the Federal Circuit affirmed the grant of summary judgment.

Judge Clevenger dissented, stating that the claim construction was not dispositive because the accused product included two structures that could be “the die” to which the construction referred. Omnium alleged that a parison cut after exiting the first die but before exiting the second die would satisfy the construction. According to the dissent, Omnium presented sufficient evidence to create a genuine dispute about whether the first alleged die could be “the die” the construction required. Thus, the dissent concluded that summary judgment was inappropriate.

Editor: Paul Stewart