Athena v. Husky (IPR2013-00290): Assignor Estoppel Does Not Bar an IPR Petition

Athena Automation Ltd. v. Husky Injection Molding Systems Ltd., IPR2013-00290, concerns a question that arises whenever an inventor leaves a company and later competes with it: can the inventor, or a business the inventor controls, use inter partes review to challenge a patent the inventor once assigned? In Paper 18, the decision on institution entered October 25, 2013, a three-judge panel answered yes. It is listed here with the Board’s precedential decisions.

Background

Athena petitioned for inter partes review of claims 1–22 of Husky’s U.S. Patent 7,670,536, titled “Molding-System Clamp,” which relates to the lock and clamp assembly of an injection molding machine. Athena had also filed petitions against two other Husky patents.

Husky’s preliminary response made a single argument. One of the named inventors of the ’536 patent, the decision notes, was the founder, co-owner, president and chief executive of Athena and one of its two directors. Husky contended that this made Athena his privy, so that Athena was barred by assignor estoppel from challenging the patent’s validity.

Assignor estoppel is a court-made, equitable doctrine. It generally prevents someone who assigned a patent, and those in privity with that person, from attacking the patent’s validity when sued for infringement by the assignee. The Board quoted the Federal Circuit’s description of it as a defense to certain infringement claims.

What the Board decided

The Board declined to deny the petition on the basis of assignor estoppel. Its reasoning turned on the statutory text:

• The statute defines who may petition. Under 35 U.S.C. § 311(a), a person “who is not the owner of a patent” may petition for inter partes review. An assignor who no longer owns the patent fits that description.
• Congress spoke broadly. The Board read § 311(a) as a clear expression of a broad grant of the ability to challenge patents through inter partes review.
• Contrast with the ITC. For International Trade Commission investigations, Congress provided expressly that all legal and equitable defenses may be presented, and the ITC therefore considers assignor estoppel. Congress gave the Office no similar instruction for the AIA reviews.
• Husky’s argument did not engage the statute. Husky accepted that the Office does not apply assignor estoppel in reexamination, but argued that the adjudicative nature of IPR called for a different result. The Board noted that none of those arguments addressed § 311(a).

Because an equitable doctrine did not create an exception to the statutory rule, the Board went on to the merits. It instituted review of all twenty-two claims on three grounds (anticipation by Glaesener, obviousness over Glaesener, and anticipation by Arend) and declined the remaining grounds. Along the way it concluded that Glaesener’s broad incorporation-by-reference language made a cited patent, Choi, part of Glaesener as a single reference.

Why it matters

Athena established early that the identity and history of the petitioner matter at the PTAB only to the extent the statute makes them matter. The AIA does impose petitioner-specific limits: the one-year bar of § 315(b), the civil-action bar of § 315(a), estoppel under § 315(e), and the need to name every real party in interest. Assignor estoppel is not among them. A patent owner facing a petition from a former inventor or a company the inventor runs should look to those statutory provisions rather than to equitable defenses developed in infringement litigation.

The decision also illustrates that “privity” arguments carry different weight in different settings. Privity matters a great deal under § 315(b) and § 315(e); see defining privy. Here, even assuming privity, it did not lead anywhere.

Later developments

• In Arista Networks, Inc. v. Cisco Systems, Inc. (Fed. Cir. 2018), the Federal Circuit held that assignor estoppel does not apply in inter partes review, confirming the approach the Board took in Athena.
• In Minerva Surgical, Inc. v. Hologic, Inc. (2021), the Supreme Court preserved assignor estoppel in court litigation but narrowed it: the doctrine applies only when the assignor’s invalidity defense contradicts explicit or implicit representations the assignor made in assigning the patent.

The result is a split forum: an assignor may be limited in district court yet free to petition the Board. Designations can change, so readers should check the USPTO’s current list of precedential and informative decisions.

Key takeaways

• In Athena v. Husky, IPR2013-00290, Paper 18, the Board held that assignor estoppel did not bar a petition by a company controlled by a named inventor.
• The reasoning rests on 35 U.S.C. § 311(a): any person who is not the patent owner may petition.
• Congress expressly allowed equitable defenses at the ITC but not in AIA reviews.
• The Federal Circuit agreed in Arista v. Cisco (2018); Minerva (2021) narrowed assignor estoppel in court.