Dangers Of Means Plus Function Limitations In US Patent Prosecution


By James Yang

Desire for Broad Claim Language Creates Downstream Problems

Broad patent protection is one of the goals when securing patent protection for inventions (i.e., new products and services). However, issues start to arise when the claim language becomes too broad. For example, broad claims might be construed as a means plus function limitation against the intentions of the patent prosecutor, and in some cases, those patents are invalidated as being indefinite. At least, this is the case with US patent prosecution. The patent laws of other jurisdictions treat means plus function style of claiming differently, and in my experience, less detrimental to the validity of the patent.

In Zeroclick, LLC v. Apple Inc. (Fed. Cir. June 1, 2018), which is discussed further below is a reported U.S. case where a limitation was construed as a means plus function limitation against the intentions of the patent prosecutor. Because of the unique requirements to properly use means plus function limitation in a claim, the United States District Court had construed two limitations of a patent claim as a means plus function limitation and found that the patent claims were invalid for being indefinite. Fortunately for the patent owner, on appeal, the Federal Circuit reversed and remanded for further consideration.

How a claim limitation unintentionally becomes a means plus function limitation?

The desire for broad claim language (discussed above) and the inability to add to the patent specification during examination (discussed below) create a situation where claim language can unintentionally and unfortunately trigger means plus function.

United States patent laws has specific rules for construing a limitation in a claim as a means plus function limitation. Read more at MPEP 2181. To determine whether a claim limitation is a means plus function limitation, the use of the word “means” followed by functional language creates a rebuttable presumption that the limitation is a means plus function limitation. By contrast, a claim limitation that does not use “means” triggers a rebuttable presumption that the limitation is not a means plus function limitation.

If a claim limitation does not recite means but is nonetheless construed as a means plus function limitation, then the claim limitation is limited only to the structure recited in the patent specification under 35 USC 112, paragraph 6 or 112(f). For example, a claim limitation might be construed as a means plus function limitation even if the word means is not used if the claim contains functional language which is often the case. The claim language “an attachment mechanism to secure first and second parts together” is an example of a claim limitation which includes functional language. This is broader in scope than a claim that specifically specifies a “nut and bolt.” The broader language is oftentimes preferred in claiming to secure the broadest scope claim as possible. Now, if the patent specification does not recite any structure (e.g., nut and bolt) associated with the functional language, then the claim is invalid because the scope of the claim cannot be determined (i.e., indefinite).

For experienced patent drafters, if they intend a claim limitation to be construed as a means plus function limitation, then they would use the word “means” so that the claim language is construed as a means plus function limitation. They would also describe various structure (i.e., parts, equipment, structure) that can perform the recited function into the patent specification. The patent statute requires these things under the relevant Section 112. Otherwise, if no structure exists in the patent specification, then the scope of the claim could not be determined and would be indefinite and thus invalid.

When the patent specification is being drafted, the patent drafter can control these situations much better. The patent drafter might use language in a claim which is questionable as to whether it might be construed as a means plus function limitation. The patent drafter can then include structure associated with the functional claim language in the patent specification.

However, during examination, the claim language is usually amended to secure the granted patent. In doing so, the patent prosecutor might use functional language in the claim that might inadvertently trigger a means plus function claim construction. During examination, nothing can be added to the patent specification such as the structure associated with the functional language. Hence, the patent prosecutor is left with a choice between include broad claim language which is one of the goals of securing a patent or to narrow down the claim to mitigate invalidity.

Zeroclick, Williamson and Media Rights Capital Cases

Zeroclick is better understood in light of two other cases that also dealt with the same issue. All three cases involved claim language that was construed as a means plus function limitation against the intentions of the patent prosecutor.

In Williamson (en banc Fed. Cir. 2015), the Federal Circuit lowered the standard to inadvertently trigger a means plus function construction of claim language that does not use the operative trigger word “means.” Under Williamson, no heavy presumption for or against construing claim language as a means plus function limitation exists.

The Federal Circuit later applied the lowered standard held in the Williamson decision in Media Rights Capital v. Capital One Financial Corporation.

When there is no heavy presumption for or against construing claim language as a means plus function limitation (Williamson), then the number of patent claims that unintentionally trigger means plus function claiming increases. This in turn also increases invalidity. In my opinion, the case that we will be discussing, Zeroclick stands for the proposition that the courts can take the lowered presumption too far. In a way, the Federal Circuit is trying to place a limit as to how far the courts can construe claim language that does not use the operative trigger word “means” as a means plus function limitation.

Below is a discussion of the limits the Federal Circuit is placing on the district courts. Zeroclick provides guidance to the lower courts as to what they need to show to hold that a limitation that does not use the operative trigger word “means” is nonetheless a means plus function limitation.

Analysis of Zeroclick Case

In Zeroclick, the patent owner (Zeroclick) was granted a patent for a device and method for controlling a computer interface without having to click a button on a mouse. The alleged infringer (Apple Inc.) argued that the claim included a means plus function limitation without reference to any corresponding structure. Thus, the claim was invalid for being indefinite.

The District Court agreed with the alleged infringer and construed two limitations as means plus function limitations. The first limitation was a “program that can operate the movement of the pointer.” The second limitation was a “user interface code being configured to detect one or more locations touched by a movement of the user’s finger on the screen without requiring the exertion of pressure and determined therefrom a selected operation.”

The District Court identified “program” as a means that performed the function of “operating the movement of the pointer over a screen,” and “user interface code” as a means of performing a twofold function: (1) to detect one or more locations touched by a movement of the user’s finger on a screen without requiring the exertion of pressure and (2) to determine therefrom a selected operation.

The District Court found that the claim did not recite any structure and described them as a “black box recitation of structure” with “no any additional clarification regarding structure of the term.”

On appeal, the Federal Circuit vacated the district court’s judgment and remanded for further proceedings. The Federal Circuit explained that the district court erred for three different reasons.

First, the mere fact that the disputed limitations incorporate functional language does not automatically convert the words into means for performing for such functions.

Second, the terms were removed from their context which strongly suggested the plain and ordinary meaning of the terms. Based on a review of the patent specification, the Federal Circuit treated these terms as referring back to structure mentioned in the patent specification. In particular, they understood these terms as “specific references to conventional graphical user interface programs or code, existing in prior art at the time of the inventions.” Read pages 8 and 9 of the opinion here.

Third, the terms “program” and “user interface code” were effectively treated as nonce words and a substitute for “means.”

The Zeroclick opinion gives patent owners more leeway in implying a structure from the language of the specification associated with a function, and thus making it more difficult for claim language to be unintentionally construed as a means plus function limitation.  In this regard, this increases the presumption against construing the claim language as a means plus function limitation when “means” is not used.

Benefits to an Overly Broad Claim Limitation

Even though overly broad claims have their own problems with respect to validity, they are useful. By overly broad claim limitation, I’m referring to claims that appear to use a word then recite functional language such as an attachment mechanism for securing two parts together. This limitation is very broad because on the face of the claim, it only requires a mechanism that secures two parts together.

Infringers reading this claim language can understand that the claim is broad with respect to this claim limitation. Although infringers can try to claim that it is invalid, the claim is still presumed to be valid under current patent laws and they need to overcome the presumption of validity.

Mitigating Invalidity

If a claim limitation is vulnerable to attack as a means plus function limitation and is identified as such, then the patent prosecutor can include dependent claims that specifically recite the structure. For example, a claim limitation “attachment mechanism for securing two parts together” might be identified as being vulnerable to attack. If so, then dependent claims with structure associated with attachment mechanism can be added such as lock, adhesive, welding, etc.

Continuation practice also mitigates the possibility that a competitor will ultimately design around your patent portfolio. Briefly, continuation practice is the practice of filing multiple continuation patent applications based on a nonprovisional patent application for the purpose of securing broader claims and for the purpose of using the pending patent application as a vehicle to craft new claims based on the design arounds of your competitors. Also, if an alleged infringer invalidates a patent based on the same arguments used in Williamson and Media Rights Capital, then the continuation patent application can hopefully be used to craft a similar claim without the same defect.

James Yang

James Yang is a U.S. patent attorney for Stetina Brunda and an author of Navigating the Patent System.  You can find more of his articles at OC Patent Lawyer

 



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