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Be careful about using means-plus-function claims(08/23/10)
Recent cases decided by the Court of Appeals of the Federal Circuit should remind applicants of the need for care in using “means-plus-function” (or “step-plus-function” for process claims) claim language. Applicants also should understand how narrow means-plus-function limitations can be.
35 U.S.C. 112, paragraph 6, permits a limitation to be described as a “means” for performing a function and the limitation will be construed to mean the structure disclosed in the patent specification for performing that function plus equivalents of that structure. If the patent claims a “means for attaching” and the specification discloses only a nail for performing this function, a screw might be equivalent structure but glue probably would not.
In Baran v. Medical Devices Technologies, Inc. the applicant claimed a “release means for retaining the guide in the charged position” as part of a biopsy needle claimed in the ‘797 patent. The Federal Circuit affirmed a summary judgment of non-infringement because this limitation was a “means-plus-function” limitation that recited two functions: release and retain, and the accused structure of the alleged infringer was not equivalent to the structure described in the specification of the ‘797 patent. Here, the recitation of two functions tied these functions to specific structures in the specification, which limited the claim’s scope.
In Enovsys LLC v. Nextel Communications, Inc. (Federal Circuit August 3, 2010), Judge Newman’s dissent reminded us that a means plus function limitation reads on the accused device only if it contains the specific structure disclosed in the specification for carrying out the function (or its structural equivalent).
In Becton, Dickinson and Co. v. Tyco Healthcare Group LP, Judge Gajarsa’s dissent reminded us that a limitation reciting the word “means” is not always a means-plus-function limitation and is not so limited. The majority avoided the issue but Judge Gajarsa would have construed “a spring means connected to said hinged arm for urging said guard along said needle cannula toward said second position” as meaning just a spring and thus not limited to the specific structures disclosed in the specification. What the attorney and inventor thought they meant by writing the claim this way is unclear.
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