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Means-Plus-Function Claiming: A Path to The Dark Side

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By: Chase Peacock

A U.S. district court’s recent Markman claim construction order highlights once again some of the problems associated with means-plus-function claiming allowed in U.S. patent practice pursuant to 35 U.S.C. § 112(f). Because no algorithms for performing the specialized functions of the claimed “controller” of the “Tower Ride” portion of the amusement park ride “Star Wars: Rise of the Resistance,” an attraction at Star Wars: Galaxy's Edge at Disney's Hollywood Studios and Disneyland in California, are disclosed in the asserted patent, the claim term “controller” was held to be indefinite.


Patent claims ordinarily recite a specific structure, material or act.  It is possible however, to construct a claim that describes a technical feature in functional terms, referred to as means-plus-function (MPF) claim, in accordance with 35 U.S.C. § 112(f), which states that a claim, “may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.”

MPF claims tend to look broad to inventors who are not trained in the details of US patent law. By claiming a function or operation of a device rather than its specific structure, MPF claims are often mistakenly viewed as being broader in scope than more traditional claims that focus on the specific structure of the invention. Additionally, inventors sometimes believe that using MPF claims could make it more difficult for a competitor to design around the patent, as the essential functions of the invention have been claimed.

Inventors holding these views are disappointed more often than not.  A U.S. district court’s recent Markman claim construction order provides another illustration of the pitfalls of the MPF claiming format.  Because no algorithms for performing the specialized functions of the claimed “controller” of the “Tower Ride” portion of the amusement park ride “Star Wars: Rise of the Resistance,” an attraction at Star Wars: Galaxy's Edge at Disney's Hollywood Studios and Disneyland in California, are disclosed in the asserted patent, the claim term “controller” was held to be indefinite.[1]

This problem with MPF claiming should come as no surprise to inventors or their U.S. litigation counsel.  The U.S. Court of Appeals for the Federal Circuit (CAFC) has invalidated patents using the term “module” and other so-called “nonce terms” – that is, non-structural terms having no specific structural meanings. In those decisions it was pointed out that the patents’ specifications contained no adequate description or disclosure of the corresponding structure of the nonce term.  As a result, such claims have been routinely invalidated due to indefiniteness.

The problem is compounded in cases where the claimed invention involves computer programming or software, and even more so when the claimed computer performs multiple functions.  The CAFC has held that when a patent claim uses the MPF format to claim multiple identifiable functions, the specification must disclose an algorithm (or some sort of structural means) for performing each one of those functions.  If either disclosure is absent, the claim is invalid for indefiniteness.

Applying this settled precedent, once again and more recently, the dangers of using MPF language in claims are seen in a so-called Markman claim construction order of the U.S. District Court for the Middle District of Florida.  Raven Sun Creative (RSC) sued Walt Disney Parks and Resorts U.S., Inc. (Disney) for alleged infringement of a patent relating to aspects of theme park rides.  RSC alleged that Disney used its patented invention in the “Tower Ride” portion of the ride “Star Wars: Rise of the Resistance,” an attraction at the theme park Star Wars: Galaxy's Edge located at Disney's Hollywood Studios and Disneyland in California.  

Disney argued that the “controller” limitations of RSC’s patent were MPF limitations, and further that the patent failed to disclose structural support for performing the controller functions of the claims.  The district court agreed with Disney’s arguments the term “controller” should be interpreted as a nonce term governed by 35 U.S.C. § 112(f) because the claim language surrounding “controller” was all functional and the controller was described by several functions that it was “capable of causing” rather than its structure. The specification described the controller as being a generic ‘computer device’ that controls the operations of multiple systems, and the controller in RSC’s patent does not simply perform well-understood tasks and, instead, requires specialized computing functions.

The district court again agreed with Disney that the controller was disclosed in the patent as performing all of the following specialized functions:

-        causing: (a) the motor system to vertically position the rider station along the rider station tower so as to coordinate the vertical position of the rider station with imagery produced by the projector and displayed on the screen;

-        causing (b) the actuator system to position the rider station relative to the rider station trolley so as to coordinate the position of the rider station relative to the rider station trolley with imagery produced by the projector and displayed on the screen;

-        in coordinating the position of the rider station relative to the rider station tower and the rider station trolley with imagery being displayed on the screen causing: (c) the motor system to vertically move the rider station trolley and rider station along the rider station tower and the actuator system to simultaneously maintain a position of the rider station relative to the rider station trolley;

-        in coordinating the position of the rider station relative to the rider station tower and the rider station trolley with imagery being displayed on the screen causing: (d) the motor system to maintain the position of the rider station trolley and rider station along the rider station tower and the actuator system to simultaneously move the rider station relative to the rider station trolley; and

-        in coordinating the position of the rider station relative to the rider station tower and the rider station trolley with imagery being displayed on the screen causing: (e) the motor system to vertically move the rider station trolley and rider station along the rider station tower and the actuator system to simultaneously move the rider station relative to the rider station trolley.

Not only did RSC’s patent fail to disclose an algorithm for each of these functions, it failed to describe any algorithms for any of them.  RSC’s own expert conceded that programming a controller to accomplish the disclosed functions would generally take “weeks or months.”  Accordingly, the district court found that because the specification included no such algorithm or algorithms for performing the specialized functions, the “controller” MPF term was ruled indefinite and claims reciting it invalid.

This trial court decision underscores the importance of providing clear and specific structural support for each and every specialized function that is associated with a claim term when there is any possibility that the term may be considered an MPF claim term, even in the absence of the words “means for,” as was true of RSC’s patent claims.  It is not enough to assume that a person that is of ordinary skill in the art would understand the implied structure of certain terms. When dealing with computer-related functions, it may be beneficial to ask yourself, “could a brand new off-the-shelf computer perform this certain function right out of the box?”  If the answer is “no” and MFP claims must be used, specific algorithms or additional structures needed to perform each and every function must be disclosed.  While MPF claims are often viewed by uninformed inventors as being broader in scope than traditional claims, they are often in fact narrower and their functions are limited to the structural support provided in the specification. As Raven Sun Creative has recently discovered, using MPF claims could start a patent on a path to the Dark Side and generally should be avoided whenever possible.

 


[1] Raven Sun Creative, Inc. v. Walt Disney Parks and Resorts U.S., Inc., No. 6:21-cv-1864-ACC-EJK, 2023 WL ________, Order (M.D. Fla. Mar. 6, 2023).