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Athena Automation Ltd. v. Husky Injection Molding Systems Ltd.

Paper No. 18, Oct. 25, 2013

IPR2013-00290(7,670,536 B2)


Petitioner Athena filed a petition for inter partes review of claims 1-22 of U.S.P.N. 7,670,536 B2.

In its Preliminary Response, Patent Owner Husky asserted Athena is barred from bringing the IPR Petition due to the doctrine of assignor estoppel.  See Paper 23, p. 12.  Husky stated that the founder, co-owner, President, Chief Executive Officer, and 1 of 2 directors on the Board of Directors is a named inventor of the ‘536 Patent.  Thus, Husky stated there is privity of the inventor (Robert Schad) with Athena, and thus Petitioner is estopped (prevented) from challenging the patentability of the ‘536 Patent. See Paper 23, p. 12.

The PTAB instituted trial for some of the challenged claims.


The doctrine of assignor estoppel, an equitable doctrine, does not provide an exception to the statutory mandate that anyone other than the patent owner can file an IPR petitioner.


First, the PTAB cited the following:

In Semiconductor Energy Laboratory Co., Ltd. V. Nagata, the Federal Circuit explained that assignor estoppel is an equitable doctrine that prohibits an assignor of a patent or patent application, or one in privity with him, from attacking the validity of that patent when he is sued for infringement by the assignee.  Assignor estoppel is thus a defense to certain claims of patent infringement.  706 F.3d 1365, 1369 (Fed. Cir. 2013).

Then the PTAB cited AIA 35 U.S.C. § 311(a) which states: “a person who is not the owner of a patent may file with the Office a petitioner to institute an inter partes review of the patent.” (Emphasis in original.) See Paper 23, p. 12.  Under the statute, as assignor of a patent, who is no longer an owner at the time of the petition filing, may file such an IPR petition.  The PTAB explained that the statute clearly expresses Congress’ broad grant of the ability to challenge the patentability of patents through IPR.  In comparison, Congress granted all legal and equitable defenses can be presented in an ITC proceeding under 19 U.S.C. § 1337(c). See Paper 23, p. 13.

Thus, assignor estoppel is not an equitable defense for an IPR proceeding.


A copy of the PTAB order can be found here.