Skip to content

Western Digital Technologies, Inc. v. Viasat, Inc. – Drafting Functional Claims & Patent Eligible Subject Matter

Blog Post Submitted By: Madison Wayland

In 2023, Western Digital Technologies, Inc. (“Western Digital”) sued Viasat, Inc. (“Viasat”), alleging that Viasat’s media streaming systems and software infringe claims of several Western Digital patents, including US 8,504,834 (“the ‘834 patent”). In a recent district court decision, the claims of the ‘834 patent were determined to be directed to patent ineligible subject matter due to broad, functional (e.g., results-oriented) claim language lacking sufficient technical detail (Western Digital Technologies, Inc. v. Viasat, Inc., No. 22-CV-04376-HSG, 2023 WL 7739816 (N.D. Cal. Nov. 15, 2023)). The implications of this decision highlight the potential risks of drafting functional claims, particularly as it relates to patent eligibility and functional subject matter.

Representative Claim of ‘834 Patent
The ‘834 patent is directed to a media streaming system that is capable of decrypting locally stored content using a decryption key derived from a stream of data received over a network, rather than a decryption key obtained from a digital rights management (DRM) server as in the prior art. The prior art method of contacting a DRM server is considered to be a less efficient and less cost-effective approach as compared to that of the ‘834 patent, which thus improves upon the prior art. Representative Claim 14 of the ‘834 patent recites:

A method for activation of local content, the method comprising:
performing the following in a host device in communication with a storage device storing encrypted content:
receiving a stream of data from a network;
deriving a key from the received stream of data; and
decrypting the encrypted content using the key derived from the received stream of data.

Alice/Mayo Test
In determining patent eligibility of the ‘834 patent, the court turned to the Alice/Mayo test, which is a two-part analysis for determining whether a claim’s subject matter is patent eligible. In the first step of the test, it is determined whether a claim is directed to an abstract idea and, if so, the second step considers whether the claim recites an inventive concept beyond the abstract idea. Thus, step two enables a claim to retain patent eligibility even if it recites an abstract idea according to step one.

For the ‘834 patent, the court determined that, because of the functional nature of Claim 14 (i.e., claiming a functional result itself) and its recitation of generic computer components and functions (e.g., “host device,” “network,” “deriving,” and “decrypting”) that are used to achieve the claimed functional result, the broad language of the claim lacks technical or practical detail and thus is drawn to an abstract idea. Moreover, the court determined that Claim 14 did not recite any additional specific inventive concept to elevate the claims beyond the abstract idea. Despite attempts to argue that the claimed method was unexpectedly advantageous over prior art methods, the court rebutted that any such advantage of the claimed method described in the specification was “untethered” from the actual language of Claim 14, which was overly broad and relied on generic and conventional computer components and functions.

Takeaways for Functional Claiming
MPEP § 2173.05(g) defines a claim term as being functional “when it recites a feature ‘by what it does rather than what it is’ (e.g., as evidenced by its specific structure or specific ingredients),” referencing In re Swinehart, 439 F.2d 210, 212, 169 USPQ 226, 229 (CCPA 1971). Though “functional language does not, in and of itself, render a claim improper,” functional claiming can lead to issues of indefiniteness, lack of enablement, and patent ineligibility. Id. When it comes to the “abstractness” doctrine, particularly for software- or computer-related subject matter, the Western Digital v. Viasat decision serves as a reminder to be conscious of patent eligibility when selecting functional claim language.

35 U.S.C. § 112(f) (post-AIA) permits an element of a claim to be recited “as a means or step for performing a specified function without the recital of structure,” but only if at least one corresponding structure that may perform the claimed function is described in the specification. The claim will then be construed to cover that described structure as well as any “equivalents thereof.” Though functional language thus offers the benefit of broader coverage from a single claim limitation, if at least one corresponding structure is not described in the specification, “all means or methods of resolving the problem may be encompassed by the claim,” which can lead not only to abstractness issues as in the case of the ‘834 patent, but enablement and indefiniteness issues as well. MPEP § 2173.05(g), referring to Ariad Pharmaceuticals., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1353, 94 USPQ2d 1161, 1173 (Fed. Cir. 2010) (en banc). Thus, it is vital to ensure that the specification is carefully drafted to disclose at least one structure corresponding to each claimed function. When combined with structural description, practitioners may also consider that functional claim recitations may be valuable in clarifying that claim recitations cannot be performed by a human in order to address patent eligibility as it relates to mental processes (e.g., clarifying that a computer-implemented process cannot be performed by the human mind). Lastly, the Western Digital v. Viasat decision urges patent practitioners to be aware of using generic claim language (e.g., “device,” “mechanism,” “unit,” “component,” etc.), which may be considered abstract and non-inventive. In sum, if choosing a functional approach, patent practitioners should consider the connotation of potentially generic terms, while also strategically defining function-performing structure in the specification to support any functional claim language.

Drafting Functional Claims Still Risky Post-Alice by Dennis Crouch
Functional Claiming – What is “Structure” and Why is it Important? by Uday Sirohi
Functional Claims by Alexander Pechette

Back To Top