Background of means plus function limitations

A means plus function limitation is a claiming strategy that follows the format of the word MEANS plus a stated FUNCTION.  On its face, it appears very broad.  One would think that a means for fastening would encompass everything known to man that would allow one to fasten two objects.  However, this couldn’t be further from the truth.  In fact, this claim only covers the structure disclosed in the specification and clearly linked to the function stated in the means plus function limitation.  To ensure proper use of a means plus function limitation, one would have to expressly state in the specification that there is a particular function and a particular component of a widget performs such function.  Anything less would leave open the possibility that the claim could be held invalid for being indefinite as was the case for the case discussed below.

Explanation of Ex Parte Adelman

In Ex Parte Adelman, the inventor used the phrase “means for designating a plurality of members as participants in an online business community.”  To perform the analysis, you look for the stated function.  In this case, the stated function is – designating.  You then look to the specification to see what structure, if any, is disclosed in the specification that might perform the designating function.  Thereafter, you must see if such structure is linked to performing the function.  In this case, the inventor pointed to various portions of the specification that allegedly disclosed the structure that performed the function.  The Board of Patent Appeals and Interferences (BPAI) disagreed.  They held that the claim is for a computer enabled means plus function limitation, there must be some form of algorithm corresponding to the function.  The portions of the specification pointed out by the inventors disclosed generic computerized databases, but no algorithm corresponding to the designating function.  Because the specification disclosed no structure to perform the claimed function, the BPAI held that the claim was invalid for being indefinite.

Patent drafting tip

Given the heightened requirement to properly claim an invention as means plus function, the patent application must be drafted with the end in mind.  The claims should be drafted first which many patent attorney do already, then as you draft the patent application, there must be a discussion of a function and the corresponding structure or algorithm that performs the function. This is a bit like working backward but it is necessary for proper drafting of the specification.

Not always broader

The means plus function limitation isn’t always broader even though it might sound very broad on its face.  Let’s take a simple example.  If one claims a means for fastening parts A and B and discloses a nut and bolt in the specification, then this means plus function limitation would cover these things plus their equivalents.  Most likely, it wouldn’t cover an adhesive or magnetic connection or welding because these types of connections are so different.

Now, let’s say that we claim just a “fastener”.  If this is construed normally, then it would potentially include the nut and bolt and probably include the magnetic fastener.  It may even potentially include adhesives and welding.

Making an end run around Festo

Many years back, the seminal Festo case was decided by the United States Supreme Court.  The essence of the case held that if an amendment was made to narrow a claim then such limitation cannot be broadened by the Doctrine of Equivalents.

A basic patent law discussion is necessary at this point.  Infringement can be found if the accused device incorporates all of the limitations of the claim.  If so, this is known as literal infringement.  However, even if the accused device does not incorporate all of the limitations of the claim, infringement can still be found under the Doctrine of Equivalents if the differences are only insubstantial.  Hence, the Festo case held that the infringement analysis does not proceed to the second step or the Doctrine of Equivalents step for the narrowing limitation.  It is not broadened under the Doctrine of Equivalents.

The claim construction for means plus function limitations is a bit different.  No enlargement is given to the claim under the Doctrine of Equivalents.  Rather, the statute which controls how one interprets a means plus function limitation folds equivalents into the literal infringement step.  The statute says that the means plus function shall include the structure disclosed in the specification and equivalents.  Hence, if an amendment to a claim is made, it could conceivably be made in the means plus function format to potentially narrow the limitation but still have some form of equivalents available.

Let’s take our fastener example.  If a claim to a fastener is rejected but you believe that you can obtain allowance for a nut and bolt, then what are the possible ways to claim this to obtain the broadest protection.  If you claim just a nut and bolt, then you are limited to a nut and bolt and exclude other forms of fastening.  If you claim a means for fastening, then you obtain protection for the nut and bolt version plus its equivalents.

Claim strategy when multiple embodiments are disclosed

The breadth of the means plus function limitation is construed as being directed to all of the embodiments disclosed in the specification that are sufficiently linked to the function recited in the means plus function limitation.

If you have multiple embodiments, then it could be significantly less expensive to include one means plus function limitation than to include multiple independent claims in an attempt to cover each of the embodiments.  For example, if you disclose a nut and bolt, welding, adhesives, rivets, etc., you can claim all of these embodiments by using a means for fastening limitation instead of having to recite each one individually. Regardless, the means plus function claim should not be the sole claim but should be layered in with other claims that do not use the means plus function limitation.

I invite you to contact me with your patent questions at (949) 433-0900 or James@OCPatentLawyer.com. Please feel free to forward this article to your friends. As an Orange County Patent Attorney, I serve Orange County, Irvine, Los Angeles, San Diego and surrounding cities.

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.

I invite you to contact me with your patent questions at (949) 433-0900 or James@OCPatentLawyer.com. Please feel free to forward this article to your friends. As an Irvine patent attorney, I serve Orange County, Irvine, Los Angeles, San Diego and surrounding cities.

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).