Background
Corephotonics, Ltd. is a camera technology company that holds patents covering dual-aperture camera systems — the technology that allows modern smartphones to seamlessly switch between wide-angle and telephoto lenses while capturing video, eliminating the jarring jump that occurs when a device transitions between camera sensors. Apple Inc. challenged these patents through inter partes review (IPR) proceedings, arguing that the claimed inventions were obvious based on prior art references, including two prior art documents referred to as “Golan” and “Martin.” The Patent Trial and Appeal Board (PTAB) found Corephotonics’s patent claims unpatentable as obvious.
Corephotonics appealed, raising two issues: whether Apple had improperly expanded its analogous art arguments in its IPR reply brief (going beyond the scope of the petition), and whether the two cited references were actually analogous art — a prerequisite for them to be used to establish obviousness. Only analogous prior art can be considered in an obviousness analysis; non-analogous art is excluded regardless of how relevant it might otherwise seem.
The Court’s Holding
The Federal Circuit issued a mixed ruling. First, on the scope of Apple’s reply, the court found no procedural violation. Apple’s expansion of its analogous art arguments in the reply brief was a permissible response to issues Corephotonics raised in its patent owner response — it did not introduce a new theory of unpatentability but rather responded to arguments Corephotonics itself had made, which is what IPR reply briefs are designed to do.
On the analogous art analysis, the court split its ruling between the two references. For Golan, the court affirmed PTAB’s finding that it was analogous art under the “field of endeavor” test — meaning Golan was reasonably found to be in the same technological field as the claimed camera patents. This conclusion was supported by substantial evidence, and the court upheld it. However, for Martin, the court found that PTAB had failed to adequately explain its analogous art determination. Whether a reference is analogous art under either of the two available tests — the field of endeavor test or the “pertinent to the problem” test — requires a reasoned analysis. The Board’s treatment of Martin on this question was insufficiently explained to allow appellate review. The court vacated the obviousness determination and remanded for PTAB to explain whether Martin is analogous art and, if so, how that finding affects the overall obviousness conclusion.
Key Takeaways
- Prior art must be analogous to the challenged patent to be used in an obviousness analysis — PTAB must explain, with sufficient reasoning and evidence, why a reference meets the field-of-endeavor or pertinent-art standard.
- PTAB decisions that rely on analogous art without adequately explaining the basis for that finding will be remanded — conclusory analogous art findings do not survive Federal Circuit review.
- IPR petitioners may expand their analogous art arguments in reply briefs when the expansion responds to positions the patent owner took in its response, rather than introducing a brand new ground of unpatentability.
- Dual-aperture camera systems were sufficiently well-established as a field of endeavor by 2023 that prior art in that specific technical niche can be found to be in the same field as smartphone camera patents.
Why It Matters
This case reflects the Federal Circuit’s ongoing efforts to ensure that PTAB’s analogous art determinations are sufficiently reasoned and reviewable. The analogous art requirement acts as a gatekeeping function for obviousness: not all prior art can be combined to invalidate a patent, only art that is in the same field of endeavor or that a skilled artisan would have consulted to address the problem the patent solves. When PTAB does not explain why a reference meets this standard, the Federal Circuit will not rubber-stamp the result.
For companies in the smartphone and consumer electronics industry — where camera technology is a competitive battleground and hundreds of patents cover incremental improvements to multi-lens systems — this decision has practical significance. IPR challengers must make a clear and documented case that each relied-upon prior art reference is analogous; it is not enough to cite a reference and assume its relevance is obvious. Patent owners defending against IPR challenges should scrutinize the analogous art basis for each reference in the petition and challenge any that are insufficiently established. The case also clarifies the scope of permissible reply brief arguments on analogous art questions, giving petitioners more flexibility to respond to patent owner arguments without fear of procedural overreach.