The following case is an example of a claim which was not clear.  The claim language at issue was “a release means for retaining …”  Baran v. Medical Device Technologies, Inc., 2010-1058 (Fed. Cir. Aug. 12, 2010).  This is a term of art among patent attorneys known as a “means plus function” limitation.  The limitation appears broad so as to encompass any type of means for retaining.  However, Congress by statute has limited this type of claim language to encompass only the structure disclosed in the patent application and linked to the particular function recited in the means plus function limitation.

In Baran, it was unclear whether the function included only the retaining function or both the release and retaining functions.  The Court held that the claim was written in a way that the function included both the release and retaining functions.  This narrowed the claim as it now required the structure disclosed in the specification related to both releasing and retaining.  Based on this claim construction, the defendant did not infringe the claim.

By statute, if a patentee wants to make clear that they are utilizing the means plus function claim language, the patentee must use the “means” term then insert the function after the “means” term.  In this case, the patentee used the term “release” before the “means” term then followed up with the “retaining” function.  Unless there is a reason for doing so, the means plus function limitation should follow the basic format of “means” followed by a function.  Only one function should be identified at a time.

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Sometimes, it is difficult to determine whether a limitation is being claimed as a means plus function limitation.  By statute, the patent drafter can invoke a means plus function limitation by including the term means and adding a function.  Unfortunately, the courts will also at times construe a limitation as a means plus function limitation even if the operative means term is not used in the claim limitation.  This is illustrated in the following case.

Massachusetts Institute of Technology (MIT) and Electronics for Imaging, Inc. (EFI) are the assignee and exclusive licensee of U.S. Pat. No. 4,500,919 (’919 Patent) which discloses a color processing system for producing copies of originals. The claims of the ’919 Patent contained two different limitations which do not recite the operative “means” term so as to invoke 35 USC 112, 6th paragraph. Nonetheless, the first limitation “colorant selection mechanism” was construed to be a means plus function limitation, whereas, the second limitation “aesthetic correction circuitry” was not construed to be a means plus function limitation. MIT and EFI alleges that Microsoft Windows infringes the claims of the ‘919 Patent.

The Federal Circuit held that the “colorant selection mechanism” limitation is a means plus function limitation because (1) generic terms such as “mechanism,” “means,” “element,” and “device,” typically do not connote sufficiently definite structure, (2) the patentee used “means” and “mechanism” synonymously in the specification, (3) at least one dictionary equates means and mechanism, and (4) the terms “colorant selection” is not defined in the specification and has no dictionary definition.

In relation to the “aesthetic correction circuitry” limitation, the Federal Circuit held that such limitation is not a means plus function limitation because (1) the dictionary definition for “circuit” connotes sufficient structure, (2) two prior cases of the Federal Circuit have determined that “circuit” with a function (or operation of a circuit) denotes sufficient structure, and (3) it is sufficient that the term “circuit” be used in common parlance or by persons of skill in the pertinent art to designate structure even if the term covers a broad class of structures and even if the term identifies the structures by their function.

The Federal Circuit limited the meaning of “circuit” to hardware and did not extend the definition of “circuit” to include software. Massachusetts Institute of Technology v. Abacus Software, 80 USPQ2d 1225 (Fed. Cir. 2006).