In Hologic v. Minerva Surgical, the Federal Circuit held assignor estoppel barred the assignor from asserting invalidity of a patent in district court, but not the assignor relying on the Federal Circuit's affirmance of PTAB invalidating claims of another patent in an inter partes review (IPR).
See further details in the opinion. One detail caught my eye as a patent attorney, Judge Stoll questioning if it is time to revisit assignor estoppel en banc (entire panel) on the construction of the America Invents Act (AIA) due to the illogical regime being perpetuated.
In the opinion on page 30:
"In Arista, we held
that the judge-made doctrine of assignor estoppel does not
apply in the context of an inter partes review. In other
words, an assignor who sold his patent rights may file a
petition for IPR challenging the validity of that patent.
Arista Networks, Inc. v. Cisco System, Inc. At the same time, we continue to bar
assignors from challenging in district court the validity of
the patents they assigned. See, e.g., Mentor Graphics Corp.v. EVE-USA, Inc.
Our precedent thus presents an odd situation where an assignor can circumvent the doctrine of assignor estoppel by
attacking the validity of a patent claim in the Patent Office,
but cannot do the same in district court. Do the principles
underlying assignor estoppel—unfairness in allowing one
who profited from the sale of the patent to attack it—apply
in district court but not in Patent Office proceedings?
Should we change the application of the doctrine in district
court, or should we revisit our construction of the America
Invents Act and reevaluate our interpretation of the statute as prohibiting the doctrine of assignor estoppel?
Given the odd circumstance created in this case, I suggest that it is time for this court to consider en banc the
doctrine of assignor estoppel as it applies both in district
court and in the Patent Office.
We should seek to clarify
this odd and seemingly illogical regime in which an assignor cannot present any invalidity defenses in district
court but can present a limited set of invalidity grounds in
an IPR proceeding. A petitioner in an IPR proceeding may request to
cancel as unpatentable one or more claims of a patent, but
“only on a ground that could be raised under section 102 or
103 and only on the basis of prior art consisting of patents
or printed publications.” 35 U.S.C. § 311(b)."
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