Written Description for a Means-Plus-Function Claim: What Is (Not) Sufficient?

Blackboard, Inc. v. Desire2Learn Inc., Nos. 2008-1368, -1396, -1548 (Fed. Cir. July 27, 2009):

Holding:

“[W]hen a computer is referenced as support for a function in a means-plus-function claim, there must be some explanation of how the computer performs the claimed function.” Slip op. at p. 23 (citing Net MoneyIN, Inc. v. VeriSign, Inc., 545 F.3d 1359, 1367 (Fed. Cir. 2008)).

“That ordinarily skilled artisans could carry out the recited function in a variety of ways is precisely why claims written in ‘means-plus-function’ form must disclose the particular structure that is used to perform the recited function.” Slip op. at 26.

Relevant Facts:

Blackboard asserted that the structure that performs the recited “means for assigning” function is the server computer’s software feature known as the “access control manager” or “ACM.”

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The entirety of the description of the access control manager in the specification is contained in a single paragraph, which reads as follows:

Access control manager 151 creates an access control list (ACL) for one or more subsystems in response to a request from a subsystem to have its resources protected through adherence to an ACL. Education support system 100 provides multiple levels of access restrictions to enable different types of users to effectively interact with the system (e.g. access web pages, upload or download files, view grade information) while preserving confidentiality of information.
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Slip op. at 20.

The Federal Circuit affirmed the district court’s finding that the disclosure of structure described in that paragraph to be inadequate to satisfy section 112, paragraph 6, as it failed to describe “how the levels themselves are assigned to the data files in the first place.”

Comment:

This case shows the difficulty in drafting means-plus-function claims in software-related patents. “[W]hen a computer is referenced as support for a function in a means-plus-function claim, there must be some explanation of how the computer performs the claimed function.” The Federal Circuit explained:

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To avoid purely functional claiming in cases involving computer-implemented inventions, we have consistently required that the structure disclosed in the specification be more than simply a general purpose computer or microprocessor. Because general purpose computers can be programmed to perform very different tasks in very different ways, simply disclosing a computer as the structure designated to perform a particular function does not limit the scope of the claim to the corresponding structure, material, or acts that perform the function, as required by section 112 paragraph 6. Thus, in a means-plus-function claim in which the disclosed structure is a computer, or microprocessor, programmed to carry out an algorithm, the disclosed structure is not the general purpose computer, but rather the special purpose computer programmed to perform the disclosed algorithm. Consequently, a means-plus-function claim element for which the only disclosed structure is a general purpose computer is invalid if the specification fails to disclose an algorithm for performing the claimed function.
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Slip op. at 23 (citing Net MoneyIN, Inc. v. VeriSign, Inc., 545 F.3d 1359, 1367 (Fed. Cir. 2008)).