Background
Sanofi-Aventis Deutschland GmbH holds U.S. Patent No. RE47,614, directed to a drug delivery device — specifically, an injection pen that allows patients to set different dose sizes. The patent claimed a spring assembly within the device that used spring washers secured by snap-fit engagement grips. Mylan Pharmaceuticals Inc. petitioned for IPR, arguing the claims were obvious over a combination of three prior art references: Burren (a drug delivery device), Venezia (which disclosed spring washers in drug-delivery contexts), and de Gennes — an automotive reference describing clutch bearings that used spring washers with snap-fit grips.
Mylan argued that de Gennes was analogous art because it was analogous to Burren, one of the other prior art references in the combination. The PTAB accepted this framing and found all challenged claims unpatentable as obvious. Sanofi appealed, arguing that Mylan had not properly established that de Gennes was analogous to the challenged patent itself.
The Court’s Holding
The Federal Circuit reversed. The court reaffirmed the correct framework for analogous art: a prior art reference constitutes analogous art if it is (1) in the same field of endeavor as the challenged patent, regardless of the problem addressed, or (2) reasonably pertinent to the particular problem with which the inventor was involved, even if from a different field. Critically, the comparison is always between the prior art reference and the challenged patent — not between the prior art reference and another prior art reference.
Mylan had argued that de Gennes was analogous to Burren, but this framing was legally incorrect. The question is not whether two prior art references are in the same field as each other; it is whether the prior art reference in question is in the same field as the patent being challenged, or is reasonably pertinent to the problem that the patent was trying to solve. Because Mylan failed to explain how de Gennes — an automotive clutch bearing reference — was analogous to the drug delivery device patent at issue, Mylan had not met its burden to establish that de Gennes was proper prior art for obviousness. The Federal Circuit reversed the PTAB’s unpatentability finding.
Key Takeaways
- The analogous art inquiry always compares the prior art reference to the challenged patent — not to other prior art references in the proposed combination.
- An IPR petitioner who relies on a prior art reference from a different technical field (like automotive engineering) to challenge a patent in a different field (like medical devices) must affirmatively demonstrate how that reference is analogous to the patent under challenge.
- Showing that a reference is analogous to another prior art reference in the combination does not satisfy the analogous art test — the petitioner must trace the connection back to the challenged patent itself.
- The failure to establish analogous art for any one reference in a multi-reference obviousness combination can be fatal to the entire challenge.
Why It Matters
Sanofi-Aventis v. Mylan is an important reminder for IPR petitioners building complex obviousness combinations from multiple prior art references: each reference must independently satisfy the analogous art test relative to the challenged patent. It is not enough to argue that all the references are related to each other; what matters is each reference’s relationship to the patent under challenge. In high-stakes pharmaceutical and medical device IPR proceedings — where petitioners often pull from a wide range of technical literature to piece together an obviousness argument — failing to properly establish analogous art for any single reference can collapse the entire challenge.
For patent holders in industries like medical devices, drug delivery systems, and precision instruments, the decision provides a useful defensive tool: when an IPR petition relies on prior art from a disparate technical field (automotive, aerospace, consumer electronics), scrutinize whether the petitioner has actually shown that reference is analogous to the challenged patent — not just that it is analogous to another reference in the petitioner’s combination.