ABS Global Inc. v. Cytonome/ST LLC
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Go With the Flow: “A” Still Means “One or More”

The US Court of Appeals for the Federal Circuit reversed a claim construction that was adopted during an inter partes review (IPR) because the Patent Trial & Appeal Board erred in construing the contested limitation as limited to a single sample rather than including the possibility of plural samples. ABS Global, Inc. v. Cytonome/ST, LLC, Case No. 22-1761 (Fed. Cir. Oct. 19, 2023) (Reyna, Taranto, Stark, JJ.)

ABS and Genus plc (collectively, ABS) filed a petition to institute an IPR on a patent owned by Cytonome. The patent claims microfluidic devices for particle (e.g., cells, molecules and other particles of interest) processing. The claimed devices exploit the principles of laminar flow to hydrodynamically focus particles at a certain point along the flow path for inspection or other purposes. The claimed devices are capable of hydrodynamically focusing the flow of a particle-containing fluid (the sample fluid) by abutting the sample fluid on more than one side with a fluid that does not contain particles (the sheath fluid). Generally, the faster the sheath fluid flows relative to the sample fluid the more the sample fluid’s corresponding cross-section is compressed. Figure 3A of the patent is an example of how the claimed devices use sheath fluid (SF) to focus a sample fluid (S) along a channel (CL):

ABS’s petition argued that the challenged claims were anticipated or obvious at least in view of a prior publication that taught devices with a split sample stream. The Board disagreed, construing the challenged patent claims as directed to a single sample stream and concluding that ABS failed to demonstrate why those of ordinary skill—in view of the art cited in ABS’s petition—would have modified the prior art split sample stream into the claimed single sample stream. ABS appealed.

The Federal Circuit found that the Board erred in construing the challenged claims. In construing the independent claim as being limited to a single sample stream, the Board focused on two limitations: “an inlet configured to receive a sample stream” and “a fluid focusing region configured to focus the sample stream….” In limiting the claim to a single sample stream, the Board relied on the definite article preceding the second recitation of “sample stream” and noted that a plural-allowing interpretation would be inconsistent with a dependent claim that further requires the focusing fluid to be “introduced into the flow channel symmetrically with respect to a centerline of the sample stream.”

The Federal Circuit reversed the Board’s claim construction, concluding that the dependent claim was not inconsistent with a plural-streams interpretation for the independent claim and that the Board committed two errors in construing both claims. First, the Board did not properly apply what the Court refers to as the “general rule,” which is applicable to open-ended “comprising” claims that recite “a” or “an” before a noun. The Court explained that such a limitation should be construed to mean one or more unless context sufficiently indicates otherwise. Second, [...]

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Patent Owner’s Disavowal of Appeal from District Court’s Noninfringement Judgment Moots IPR Appeal

Addressing the standard for mootness in inter partes review (IPR) proceedings following a district court noninfringement judgment, the US Court of Appeals for the Federal Circuit held that a petitioner’s IPR appeal was moot after the patent owner decided not to appeal the final judgment of noninfringement. ABS Global, Inc. v. Cytonome/ST, LLC, Case No. 19-2051 (Fed. Cir., Jan. 6, 2021) (Stoll, J.) (Prost, C.J., dissenting in part).

In June 2017, Cytonome/ST filed a complaint against ABS asserting infringement of six patents, including the patent of interest in this case. ABS filed a petition for IPR of all claims of the patent. In April 2019, the Patent Trial and Appeal Board (PTAB, the Board) issued its final written decision invalidating certain claims of the patent. Two weeks later, the district court granted ABS partial summary judgment, holding that the accused products did not infringe any of the asserted patent’s claims. In June 2019, ABS appealed the PTAB’s final written decision. In a briefing before the Federal Circuit, Cytonome/ST’s counsel filed an affidavit stating that Cytonome/ST “has elected not to pursue an appeal of the district court’s finding of non-infringement as to the patent and hereby disclaims such an appeal.” In June 2020, the district court entered final judgment, including as to non-infringement of the patent.

The Federal Circuit dismissed ABS’ appeal of the PTAB’s final written decision on the ground that the appeal was moot in view of the district court’s non-infringement judgment. The Court characterized the question as one under the voluntary-cessation doctrine. In the context of intellectual property infringement cases, the voluntary-cessation doctrine requires the property owner claiming mootness to prove that the “allegedly wrongful behavior could not reasonably be expected to recur,” i.e., that it will not assert the intellectual property right against the same accused products again. If it does, the burden shifts to the accused infringer to show that it “engages in or has sufficiently concrete plans to engage in activities” that would not be covered by the property owner’s non-assertion decision.

Applying the doctrine, the Federal Circuit concluded that Cytonome/ST could not reasonably be expected to assert infringement of the patent against ABS because ABS had already secured a district court judgment that the accused products do not infringe and Cytonome/ST disclaimed any appeal of the non-infringement judgment. In effect, ABS was insulated from liability for infringement, including for future infringement for products that are “essentially the same” as ABS’ currently accused products pursuant to the Kessler doctrine. Further, the Court found that ABS had not demonstrated it could reasonably expect Cytonome/ST to sue it for infringement of the patent in the future as ABS had not shown it had current or concrete future plans to engage in activities not covered by Cytonome/ST’s disavowal: “Cytonome’s disavowal of its right to appeal the summary judgment of noninfringement ‘estops Cytonome from asserting liability against ABS for infringement of the…patent claims in connection with the accused products, thereby allowing ABS to make, use, and sell those products [...]

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