Canada: To Claim (Broadly), Or Not To Claim? The Double-Edged Sword Of Patents

Sisvel International S.A. v. Sierra Wireless, Inc., 2022-1387, 2022-1492 (Fed. Cir. Sept 1, 2023)

Writing patent claims is a delicate art: claims that are overly narrow are less likely to be infringed while claims that are overly broad are more easily invalidated. This was the predicament faced by Sisvel International S.A. ("Sisvel"), whose broadly worded claims were invalidated by the Patent Trial and Appeal Board ("PTAB"). On September 1, 2023, the Court of Appeals for the Federal Circuit ("CAFC") affirmed the written decision of the PTAB, demonstrating the CAFC's reluctance to limit claims to embodiments outlined in the specification, especially when the language of the claims supports a broader construction.

Background

Sisvel owned U.S. Patent No. 7,433,698 ("the '698 Patent") and U.S. Patent No. 8,364,196 ("the '196 Patent"), related to methods and apparatuses for exchanging frequency information between a mobile station (such as an individual's cell phone) and a central mobile switching center. Both patents described a "channel/cell reselection method" of a mobile device's cellular network involving the following steps:

1. receiving a connection rejection message in a mobile cellular network;
2. observing at least one parameter of said connection rejection message; and
3. setting a value, or selecting a channel, for a new connection attempt based on at least one parameter of the connection rejection message.

Sierra Wireless Inc. had petitioned the PTAB for inter partes review of both patents, challenging certain claims directed at channel reselection for invalidity based on anticipation and/or obviousness. The PTAB issued a final written decision finding the claims at issue unpatentable in view of certain prior art and denied Sisvel's motion to amend the claims.

On appeal, Sisvel challenged the PTAB's construction of the claim term "connection rejection message" and the denial of its motion to amend the claims of the '698 Patent.

Claim Construction

Sisvel had proposed construing the term "connection rejection message" as "a message from a Global System for Mobile Communication ("GSM") or Universal Mobile Telecommunications System ("UMTS") telecommunications network rejecting a connection request from a mobile station". While the specification only expressly disclosed embodiments in a UMTS or GSM network, it also broadly taught:

The PTAB construed the term broadly, applying a plain and ordinary meaning of "a message that rejects a connection". The PTAB found that the language of the specification was clearly "permissive, not mandatory". At most, the specification explained that "the cellular telecommunication system can be a UMTS system or GSM system; not that the cellular telecommunication system must be a UMTS system or GSM system".

The CAFC agreed with the PTAB, finding that "the intrinsic evidence provides no persuasive basis to limit the claims to any particular cellular networks. To the contrary, the claim language itself is not so limited". While Sisvel argued that GMS and UMTS are the only networks identified by the patents that actually send connection rejection messages, Sisvel provided no evidence for this proposition. As such, the CAFC found no basis to accept that a skilled person would read the broad claim language to be limited to only GMS and UMTS networks.

Motion to Amend

Sisvel had also submitted a motion to amend claim 10 of the '698 Patent. The original claim language required that the value in a new connection setup attempt be "based on" at least one parameter (as outlined above), while the amendment removed this requirement and replaced it with "using". The PTAB denied Sisvel's motion, concluding that the amendments would enlarge the scope of the claim.

The CAFC rejected Sisvel's appeal, stating the following:

"In the context of these claims, "using" is broader than "based on." Whereas the original claim language required that the value in a new connection setup attempt be at least in some respect impacted by (i.e., "based" on) the frequency parameter, the substitute claim removes this requirement. The removal of a claim requirement can broaden the resulting amended claim, and that is what has occurred here."

The CAFC emphasized that while a patent owner may amend its claims during an inter partes review, the amendments "may not enlarge the scope of the claims of the patent".¹

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