Petitioner's burden in IPR : CAFC Alert

What’s the Problem?  CAFC reverses PTAB for identifying the problem to be solved in finding combined references analogous when the burden was properly on the Petitioner

| May 11, 2023

Sanofi-Aventis Deutschland GMBH v. Mylan Pharmaceuticals Inc.

Decided: May 9, 2023

Before Reyna, Mayer and Cunningham. Opinion by Cunningham.


The Court reverses a PTAB final written decision finding all challenged claims of Safoni’s patent unpatentable as obvious over prior art.  The Court held that Mylan improperly argued a first prior art reference is analogous to another prior art reference and not the challenged patent.  Therefore Mylan failed to meet its burden to establish obviousness premised on the first reference since the Board’s factual finding that the first reference is analogous to the patent-in-suit is unsupported by substantial evidence.


Mylan filed an IPR against Sanofi’s RE47,614 (“the ‘614 patent”) alleging its unpatentability in light of a combination of three prior art references: (1) U.S. Patent Application No. 2007/0021718 (“Burren”); (2) U.S. Patent No. 2,882,901 (“Venezia”); and (3) U.S. Patent No. 4,144,957 (“de Gennes”).  Claim 1 of the ‘614 patent is directed to a drug delivery device with a spring washer arranged within a housing so as to exert a force on a drug carrying cartridge and to secure the cartridge against movement with respect to a cartridge retaining member, the spring washer has at least two fixing elements configured to axially and rotationally fix the spring washer relative to the housing. 

Mylan asserted that Burren with Venezia taught the use of spring washers within drug-delivery devices and relied on de Gennes to add “snap-fit engagement grips” to secure the spring washer.  Burren and Venezia were both within the field of a drug delivery system.  However, de Gennes was non-analogous art being directed to a clutch bearing in the automotive field.  Sanofi argued that the combination was improper because de Gennes was non-analogous art.  Mylan responded that de Gennes was analogous in that it was relevant to the pertinent problem in the drug delivery art and cited to Burren as providing a problem which a skilled artisan may look to extraneous art to solve.

The PTAB found that Burren in combination with Venezia and de Gennes does render the challenged claims unpatentable relying on the “snap-fit connection” of de Gennes as equivalent to the “fixing elements” of the ’614 patent.  Sanofi appealed.


In its appeal, Sanofi argued that the PTAB “altered and extended Mylan’s deficient showing” by analyzing whether de Gennes constitutes analogous art to the ’614 patent when Mylan, the petitioner, only presented its arguments with respect to Burren (i.e. other prior art).  Mylan countered that the Board had found de Gennes as analogous art because there was “no functional difference between the problem of Burren and the problem of the ‘614 patent.”

In its review of the law governing whether prior art is analogous, the CAFC noted that “we have consistently held that a patent challenger must compare the reference to the challenged patent” and, citing precedent, noted that the proper test is whether prior art is “reasonably pertinent to the particular problem with which the inventor is involved.”  The CAFC expanded thereon stating:

Mylan’s arguments would allow a challenger to focus on the problems of alleged prior art references while ignoring the problems of the challenged patent. Even if a reference is analogous to one problem considered in another reference, it does not necessarily follow that the reference would be analogous to the problems of the challenged patent…[broad construction of analogous art]…  does not allow a fact finder to focus on the problems contained in other prior art references to the exclusion of the problem of the challenged patent.

The Court re-emphasized that the petitioner has the burden of proving unpatentability and that they have reversed the Board’s patentability determination where a petitioner did not adequately present a motivation to combine.


The CAFC concluded that the Board’s decision did not interpret Mylan’s obviousness argument as asserting de Gennes was analogous to the ’614 patent, but rather improperly relied on de Gennes being analogous to the primary reference, Burren.  As such, Mylan did not meet its burden to establish obviousness premised on de Gennes; and therefore, the Board’s factual finding that de Gennes is analogous to the ’614 patent is unsupported by substantial evidence.  The Court reversed the finding of obviousness.

Take away:

  • Relying on non-analogous art to support an obviousness contention requires looking at the problems the inventor of the patent-in-issue would find pertinent not those set forth in other relied upon prior art.  Arguments that a problem solved by non-analogous art should focus on the inventor of the patent-in-issue as recognizing the problem to be solved not generally problems recognized in the art.
  • Petitioner’s in IPRs should be cautious relying on the PTAB formulating an argument outside of those clearly set forth in their filings.  Extrapolation of Petitioner’s arguments by the PTAB can open the possibility of a reversal based on lack of substantial evidence.

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