Means-Plus-Function in the Prior Art Context

Fresenius USA, Inc. v. Baxter Int'l, Inc., Nos. 2008-1306, -1331 (Fed. Cir. Sept. 10, 2009):

Relevant Holding:

“[A] challenger who seeks to demonstrate that a means-plus-function limitation was present in the prior art must prove that the corresponding structure—or an equivalent—was present in the prior art.” Slip op. at 16.

Relevant Facts:

Among many issues and facts in this case, the challenger neither identified the structure in the specification that corresponds to the means at issue nor compared it to the structures present in the prior art.

Comments:

Regarding means-plus-function limitations, the Court requires a structure analysis and a functional analysis to prove infringement as well as invalidity.

“Just as a patentee who seeks to prove infringement must provide a structural analysis by demonstrating that the accused device has the identified corresponding structure or an equivalent structure, a challenger who seeks to demonstrate that a means-plus-function limitation was present in the prior art must prove that the corresponding structure—or an equivalent—was present in the prior art.” Slip op. at 16.