Public Policy Role of PTAB Clashes with
The doctrine of assignor estoppel prevents prior owners/inventors of a patent from later challenging the patent's validity. Assignor estoppel's premise is that the assignor "should not be permitted to sell something and later assert that what was sold is worthless, all to the detriment of the assignee."
While exceptions to assignor estoppel have existed since its inception, the Federal Circuit has found that the AIA can be leveraged to circumvent the doctrine—that is, while a prior owner of a patent may not challenge the patent's validity at district court, it may challenge the validity at the PTAB.
In
However, Arista only addressed whether an assignor may challenge an assigned patent at the PTAB—the case did not address the effect of a PTAB invalidation on a parallel district court proceeding.
In this case, an inventor assigned his rights to two patent applications to his employer, plaintiff
Hologic sued Minerva in the District of
The case proceeded to a jury trial on the remaining issues. After trial, the Federal Circuit affirmed the Board's invalidity decision. Thereafter, the district court denied Hologic's post-trial motions relating to the invalidated patent, finding Hologic collaterally estopped from pursuing claims based upon the invalidated patent.
Hologic appealed the district court's decision that it was collaterally estopped from asserting the patent invalidated by the PTAB, arguing that assignor estoppel still precluded Minerva from relying upon the Federal Circuit's affirmance of the PTAB's invalidation. The Federal Circuit rejected Hologic's argument and affirmed the district court, begrudgingly citing Arista ( here):
Although Minerva would have been estopped from challenging the validity of the '183 patent claims in district court, it was able to challenge their validity in an IPR proceeding and, hence, circumvent the assignor estoppel doctrine. Minerva had the right to do so under the AIA and this court's precedent. This court has held that the doctrine of assignor estoppel does not bar an assignor from filing a petition for IPR.
Since Minerva was not estopped from challenging the patent's claims at the PTAB, and since a patentee is estopped from asserting a patent found invalid in a prior proceeding, the court found that Hologic was collaterally estopped from asserting infringement of the invalidated claims in its post-trial motions.
Stay tuned.
Originally published
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