Federal Circuit Vacates PTAB Decision on Motivation to Combine

The Federal Circuit has vacated and remanded a decision by the Patent Trial and Appeal Board (PTAB or Board), finding that Palo Alto Networks failed to establish that certain claims of Centripetal Networks patents were unpatentable as obvious.

The court said the PTAB erred by not adequately explaining its reasoning in connection with its motivation to combine analysis.

Palo Alto Networks, Inc. (“PAN”) successfully petitioned for inter partes review (IPR) of claims 1–18 of Centripetal Networks, LLC’s (“Centripetal’s”) U.S. Patent No. 10,530,903 (the “’903 patent”), asserting unpatentability for obviousness based on prior-art references.

As the court noted, “Obviousness is a question of law with underlying factual issues . . . .”

Also, the

test for obviousness is not . . . that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art.

In addition, where elements of the proposed invention are found in multiple prior art sources, “[T]here must exist a motivation to combine various prior art references in order for a skilled artisan to make the claimed invention.”

And “[w]hether a skilled artisan would have been motivated to combine references” is a “question[] of fact reviewed for substantial evidence.”

As the US Patent and Trademark Office (USPTO) explains,

When setting forth a rejection, Office personnel are to continue to make appropriate findings of fact as explained in MPEP § 2141 and § 2143 and must provide a reasoned explanation as to why the invention as claimed would have been obvious to a person of ordinary skill in the art at the relevant time. This requirement for explanation remains even in situations in which Office personnel may properly rely on common sense or ordinary ingenuity.

Examples of rationales supporting a conclusion of obviousness include combining prior art elements according to known methods to yield predictable results.

The ’903 patent is titled “Correlating Packets In Communications Networks” and discloses a “computing system” that may:

1. “identify packets received by a network device from a host located in a first network,”
2. “generate log entries corresponding to the packets received by the network device,”
3. “identify packets transmitted by the network device to a host located in a second network,”
4. “generate log entries corresponding to the packets transmitted by the network device,” and
5. “correlate the packets transmitted by the network device with the packets received by the network device.”

PAN’s IPR petition included one ground of unpatentability, asserting that claims 1–18 would have been obvious over U.S. Patent Application Publication No. 2014/0280778 (“Paxton”) and U.S. Patent No. 8,413,238 (“Sutton”) in view of U.S. Patent No. 8,219,675 (“Ivershen”).

Paxton is titled “Tracking Network Packets Across Translational Boundaries” and “relates generally to identifying network packets, and more particularly, to determining the identity of network packets as they traverse boundaries that perform Network Address Translation (NAT).”

Sutton is titled “Monitoring Darknet Access To Identify Malicious Activity” and “relates to identification of potentially malicious activity based upon access attempts to darknet addresses.”

According to PAN,

[A person of ordinary skill in the art] would have been motivated to modify Paxton’s computing system to, after the correlating, notify administrators of devices involved with the malicious activity . . . and generate rules to be provisioned to a packet-filtering device . . . and used for identifying, filtering, and/or blocking host devices’ future packet communications . . . , as taught by Sutton . . . .

The Board explained that “the argument that must be evaluated is whether Paxton, as modified by Sutton, would have taught the recited transmitting responsive to the correlation.”

According to the court, the PTAB correctly identified the combination asserted: one in which “a packet is detected as communicated to/from a darknet address (post-boundary),” where “Paxton discloses the ability to identify the hosts transmitting/receiving the packet (pre-boundary),” and where “Sutton teaches making that identification known to administrators and/or implementing rules to identify or drop future packets to prevent further malicious communications.”

The Board concluded that PAN “ha[d] not provided [it] with argument and evidence sufficient to establish by a preponderance of the evidence that claim 1 would have been obvious.”

The parties disagreed on whether the PTAB found a motivation to combine the Paxton and Sutton prior art and on what the Board meant when it said that “the necessary bridge” between the prior art references was missing.

Under Federal Circuit precedent, the PTAB “must make a finding of a motivation to combine when it is disputed.”

As the USPTO explains, to reject a patent claim based on combining prior art elements, Patent Office personnel must articulate the following:

1. a finding that the prior art included each element claimed, although not necessarily in a single prior art reference, with the only difference between the claimed invention and the prior art being the lack of an actual combination of the elements in a single prior art reference;
2. a finding that one of ordinary skill in the art could have combined the elements as claimed by known methods and that in combination, each element merely performs the same function as it does separately;
3. a finding that one of ordinary skill in the art would have recognized that the results of the combination were predictable and
4. whatever additional findings based on the Graham [Graham v. John Deere Co., 383 U.S. 1 (1966)] factual inquiries may be necessary, in view of the facts of the case under consideration, to explain a conclusion of obviousness.

According to the court,

Although identifying a motivation to combine ‘need not become [a] rigid and mandatory formula[],’ the [Board] must articulate a reason why a [person of ordinary skill in the art] would combine the prior art references.” … If the Board finds that there would have been no motivation to combine [references] . . . , it must expressly say so with an adequate explanation.

The court held that the PTAB failed to make this finding and explain what it meant by “necessary bridge.”

According to the court, the Board

never made a clear finding on whether a person of ordinary skill in the art would have been motivated to modify Paxton by adding Sutton’s step of transmitting a notification of malicious activity after Paxton’s correlation step as proposed by PAN.

Thus, said the court, “the Board erred by not addressing the evidence and the argument for the motivation to combine and by failing to provide an adequate explanation for its finding.”

In addition, the court said the Board failed to resolve “whether Paxton, as modified by Sutton, would have taught the recited transmitting responsive to the correlation.”