Fed. Cir. Provides Insight on Conditional Features
In Sierra Wireless v. Sisvel S.P.A., Appeals 2023-1059, -1085, -1089, -1125 (Fed. Cir. Mar. 10, 2025), the Federal Circuit vacated and remanded a PTAB decision that had found claims 1, 2, and 6-8 of U.S. Patent No. 7,869,396 (“the ’396 patent”) obvious. In particular, the Federal Circuit found that the features in claim 1 of the ’396 patent were not conditional, and gave them patentable weight.
Claim 1 of the’396 patent recites a variation of an automatic repeat request (ARQ), in which a receiver sends a message to a transmitter if expected data is not received, thereby enabling retransmission of the missing data. In claim 1, a timer is started when data is detected as missed. The timer is then stopped if the missed data is subsequently received; on the other hand, if the timer is not stopped and expires, a status report is sent to the transmitter. More specifically, claim 1 recites:
1. A method of performing automatic repeat request (ARQ) in a wireless communication system, the method performed by a receiver and comprising:
[a] detecting whether at least one data block to be received from a transmitter is missed;
[b] starting a timer when the at least one data block is detected as missed;
[c] stopping the timer when the at least one data block is received from the transmitter while the timer is running, in order to prevent a triggering of a status report before the timer expires; and
[d] transmitting the status report to the transmitter after the timer expires, wherein the status report comprises a positive acknowledgement indicating receipt of at least one received data block.
The PTAB found that limitations 1[c] and 1[d] were mutually exclusive. Due to this finding, the PTAB held that “the prior art need only disclose limitations 1[a], 1[b], and 1[c] or limitations 1[a], 1[b], and 1[d] to anticipate claim 1.” Sierra Wireless at 4-5.
However, the Federal Circuit disagreed, stating, “the plain and unambiguous language of claim 1 requires that a method, to come within the claim, must perform both limitations 1[c] and 1[d] where their preconditions apply.” Id. at 5. The Federal Circuit apparently did not require that all steps be performed in the same iteration of the method. The Federal Circuit then went on to determine that the PTAB’s finding that the prior art disclosed limitation 1[c] was not supported by substantial evidence, and therefore vacated the PTAB’s holding that claim 1 was obvious over the prior art.
This decision appears to be in conflict with (and effectively overrules) Ex Parte Schulhauser, Appeal 2013-007847, 2016 WL 6277792 (PTAB Apr. 28, 2016) (precedential). In Schulhauser, the PTAB considered conditional features (e.g., containing “if” language) in a method claim, and concluded that two of the features—related to if electrocardiac signal data is or is not within a threshold—were mutually exclusive. Because the PTAB found that the features were mutually exclusive, it concluded:
The Examiner did not need to present evidence of the obviousness of the remaining method steps of claim 1 that are not required to be performed under a broadest reasonable interpretation of the claim (e.g., instances in which the electrocardiac signal data is not within the threshold electrocardiac criteria such that the condition precedent for the determining step and the remaining steps of claim 1 has not been met).
Id. at 4.
However, it should be noted that this reasoning only applied to the method claim, and did not apply to the system claim. See Id. at 6. See also M.P.E.P. § 2111.04(II).
Sierra Wireless may be useful to practitioners in resolving ambiguities regarding if claim features should be given patentable weight. In particular, in method claims, it is now more clear that to anticipate or render obvious a claim, the prior art must show the conditional features where their preconditions apply. Put another way, conditional features in method claims should be given patentable weight.
