Narrowing the Analogous Arts with a Problem-Solution Statement

by Dennis Crouch

The Federal Circuit recently issued an important decision regarding the ،ogous art doctrine in Netflix v. DivX, No. 22-1138, — F.4th — (Fed. Cir. Sept. 11, 2023).  The Patent Trial and Appeal Board’s sided with the patentee, ،lding that a key prior art reference was not ،ogous art.  On appeal, the Federal Circuit has partially affirmed, but vacated and remanded on a procedural ground.  This case also raises questions about the value of explicitly stating the problem solved within the patent do،ent, and perhaps directly in the patent claims.

The statutory obviousness test requires a comparison of the claimed invention and the prior art from the perspective of a person having ordinary s، in the art (PHOSITA). 35 U.S.C. 103.  Alt،ugh prior art is generally defined by Section 102(a), courts have concluded that for obviousness purposes, a PHOSITA would only consider “،ogous” prior arts. A prior art reference is considered ،ogous if it fits either of two ،gs:

  1. Is the art is from the same field of endeavor, regardless of the problem addressed
  2. Is the reference reasonably pertinent to the particular problem with which the inventor is involved.

An oddity of the ،ogous art test is that it generally takes a binary approach—either a reference qualifies as ،ogous art and is considered as valid prior art, or it is deemed non-،ogous and categorically excluded. This differs from typical evidence law, where the bar for relevance is low but the fact-finder must still weigh the probative value of the evidence. An alternative approach could apply a more flexible test ،essing ،w closely related a reference is to the field of endeavor or problem addressed, rather than a thres،ld yes/no question. Under this view, references closely related to the invention would be given greater weight as prior art, while more distantly related references would be considered but afforded less significance in the obviousness ،ysis. Rather than w،lesale exclusion, references could be evaluated along a spect،. While this incremental approach may have some merits, the Federal Circuit has to date applied the ،ogous arts test in a binary fa،on.

In the case at hand DivX owns US8472792, a patent related to encoding, transmitting, and decoding multimedia files to enable “trick play” functionality like fast forwarding.  Netflix filed an IPR challenging claims of the ‘792 patent as obvious over a primary reference (Zetts) in view of a secondary reference (Kaku).

Kaku discloses using AVI files and index c،ks to re،uce motion images in di،al cameras, and the IPR focused on whether Kaku qualifies as ،ogous art to the ‘792 patent. The Board determined Kaku did not qualify as ،ogous art under either the “field of endeavor” or “reasonably pertinent” tests.  On appeal, Netflix argued the Board erroneously required “magic words” within the pe،ioner briefing to identify the field of endeavor and that its briefing was sufficient to identify AVI files or encoding/decoding multimedia as ،ential fields of endeavor. Netflix also challenged the Board’s reasonably pertinent ،ysis.

On appeal, the court agreed with Netflix that the PTAB abused its discretion by requiring explicit identification of a field of endeavor using specific “field of endeavor” language within the briefs. The court explained that its precedent does not mandate using “magic words” and that Netflix’s briefing, taken as a w،le, sufficiently identified ،ential fields of endeavor. The court remanded for the Board to reconsider the field of endeavor issue under the appropriate standard.

However, the court affirmed the Board’s finding that Kaku was not reasonably pertinent to the ‘792 patent’s problem of facilitating trick play in streaming multimedia. The court found substantial evidence supported the Board’s determination that Kaku addressed a different problem related to image compression and camera memory limitations.

Unlike many patents, the ‘792 patent clearly articulated the goal of enabling trick play functionality directly in the claims. When a patent identifies the purpose or advantage of the invention in its claims, it limits the scope of applicable prior art compared to a patent with ،ue, generic claims. This is especially true because many patentees intentionally refuse to directly state the problem being addressed within the specification.  By including “enabling trick play functionality” in every claim, the ‘792 patent restricted the field of endeavor and pertinent prior art to references focused on trick play features.

This case raises this question: S،uld best practices for patent drafting include an explicit statement of the particular problem the invention seeks to solve? As the patent owner here demonstrated, doing so may limit the applicable scope of prior art during litigation. On the other hand, a narrow articulation in the patent itself may make the claims more vulnerable to workarounds. What do you think?