Non-Prior Art Evidence May Be Used to Prove Inherency

| Ari FeinsteinKaren Cassidy Selvaggio


Before Lourie, Dyk, and Moore. Appeal from the U.S. District Court for the Northern District of Illinois.

Summary: Evidence of the properties of claimed embodiments may be proper evidence of inherency, even when the evidence itself is not prior art.

Hospira sued Fresenius for infringement of a patent for its ready-to-use dexmedetomidine product (Precedex Premix). Following a bench trial limited to validity of two claims, the district court concluded that one embodiment of claim 6 (the only claim at issue on appeal) was expressly taught in the prior art. The sole remaining issue was a limitation requiring that the concentration of the active agent decrease by no more than 2% when stored for 5 months. Relying on fact and expert testimony related to the stability of both Hospira’s Precedex Premix and Fresenius’s generic product, the district court concluded the stability limitation was inherent, and found claim 6 invalid as obvious. Hospira appealed.

On appeal, Hospira argued that the district court erred in its application of the inherency doctrine by considering the inherent properties of non-prior art embodiments—specifically, that every tested sample in the record was either from Hospira’s Precedex Premix New Drug Application or Fresenius’s Abbreviated New Drug Application, neither of which was in the prior art. The Federal Circuit rejected this argument, explaining that “[e]xtrinsic evidence can be used to demonstrate what is necessarily presentin a prior art embodiment even if the extrinsic evidence is not itself prior art.” The Federal Circuit also rejected Hospira’s argument that the district court erred by considering only samples made using a manufacturing process first described in the patent. The Federal Circuit explained that claim 6, which is not a method claim or product-by-process claim, included no limitations regarding the manufacturing process. Because importing such limitations into the claim would be improper, the district court did not err by considering samples without regard to the process by which they were prepared.

Hospira next argued that the district court erroneously applied a lower “reasonable expectation of success” standard rather than the higher “necessarily present” standard to the inherency issue. The panel rejected this argument as well. The Federal Circuit acknowledged that the district court unnecessarily analyzed whether a person of ordinary skill in the art would have had a reasonable expectation of success in achieving the “about 2%” limitation, however, that error “did not infect its inherency analysis and findings.” Unpersuaded by Hospira’s arguments, the Federal Circuit affirmed the district court’s conclusion that claim 6 was invalid as obvious.

Editor: Paul Stewart