A Claim for "a" Phosphate Is Not Infringed By a Mixture of More Than One Phosphate

Case: Norian Corp. v. Stryker Corp. , No. 05-1172 (Fed. Cir. 12/6/05)


The One Sentence Summary: The word "a sodium phosphate" meant a single phosphate rather than a mixture of more than one phosphate where the narrow term "consisting of" was used, and broader scope was surrendered during prosecution of the patent.


What They Were Fighting About: The patent claimed a cement kit for setting bones with a "kit consisting of . . . a solution consisting of water and a sodium phosphate" The defendant used a mixture of phosphates rather than a single phosphate. The district court found that "a sodium phosphate" was singular, and defendant did not infringe. The Federal Circuit affirmed.

Federal Circuit Holdings:

• The district court properly construed a claim for a "kit consisting of . . . a solution consisting of water and a sodium phosphate" to exclude products containing a solution made from a mixture of different sodium phosphates.
• Although the words "a" or "an" can sometimes mean "one or more", the specification and prosecution history can show the term was used to mean only one. This is particularly true when the narrow term "consisting of" precedes "a" or "an". "Consisting of" is narrower in scope than "comprising."
• The specification supported a single solute interpretation where it included a chart of solutions made only with single solutes.
• The prosecution history supports a narrow interpretation because the applicant had to amend the claim to use the narrow term "consisting of".
• The surrender of scope in the prosecution history is not limited to the specific prior art that the applicant sought to avoid. Everything surrendered is gone, even if a narrower argument would have distinguished the prior art at issue.
• Because applicant narrowed its claims during prosecution, prosecution history estoppel prevents application of the doctrine of equivalents.