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Timing matters in inter partes review

Inter partes review (IPR) offers parties an expedited opportunity to challenge the validity of a patent outside of court. But, as one challenger recently learned the hard way, it’s critical that arguments against patentability be raised at the proper time.

Out of the frying pan …

Frymaster LLC holds a patent on a system for measuring the state of cooking oil degradation in a deep fryer using a sensor. The sensor detects when the level of the total polar materials (TPMs) generated when oil degrades is too high.

Henny Penny Corp. (HPC) challenged the validity of the patent in an IPR proceeding. Under IPR, the Patent Trial and Appeal Board (PTAB) can reconsider and cancel an already-issued patent based on certain types of “prior art” that made the claimed invention obvious and therefore unpatentable.

HPC claimed that the patent was obvious in light of two patents, referred to as Kauffman and Iwaguchi. In its initial IPR petition, HPC contended that:

  • Kauffman included every limitation in the Frymaster patent (limitations define the breadth of a patent) except the sensor for measuring TPMs, and
  • Iwaguchi would have motivated a “person of ordinary skill” in the relevant field to provide a sensor to measure TPMs to monitor cooking oil degradation.

After the PTAB began review proceedings, Frymaster filed its response. It argued that it wasn’t predictable that integrating Iwaguchi’s temperature-sensitive probe into Kauffman’s apparatus would measure oil quality.

In reply, HPC shifted gears and argued that integration was unnecessary because Kauffman’s sensor alone was capable of monitoring TPMs, although Kauffman didn’t explicitly disclose use of its sensor to measure TPMs. The PTAB, however, disregarded this argument, focusing only on the petition argument. It went on to find the challenged patent claims weren’t obvious, and HPC appealed to the U.S. Court of Appeals for the Federal Circuit.

… Into the fire

The court found that the PTAB was within its rights to hold HPC to the obviousness theory it asserted in its original petition. Noting the expedited nature of IPR proceedings, the Federal Circuit explained that petitioners must comply with the requirement that the initial petition identify “with particularity” the evidence that supports the grounds for the challenge to each patent claim. An IPR petitioner, the court held, may not raise in reply “an entirely new rationale” for why a claim would have been obvious.

HPC’s petition proposed a single obviousness theory — modifying Kauffman’s system to include Iwaguchi’s sensor. Thus, the court found, the PTAB was entitled to disregard the second theory raised only in the reply.

Don’t get burned

The court’s decision provides clear guidance to those who wish to challenge an issued patent through IPR. It’s imperative to include every rationale for obviousness in the petition because those raised subsequently will be disregarded.

Henny Penny Corp. v. Frymaster LLC, No. 18-1596, Sept. 12, 2019, Fed. Cir.


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