In Brief: An inventor can’t claim their invention is invalid after an assignment.

Here’s What Happened:

Csaba Truckai was one of the named inventors of a device used to treat vaginal bleeding. He and his fellow inventors founded a company called NovaCept, Inc. Csaba and his fellow inventors applied for a patent and then assigned it to their company.

Cyctyc Corporation acquired NovaCept and all of its intellectual property, including its patents and patent applications. As part of the deal, NovaCept warranted the validity and enforceability of its intellectual property. Then Cyctyc was acquired by Hologic, Inc. After Hologic took over, it filed a continuation patent involving the device.

Csaba left NovaCept and started his own company, Minerva Surgical Inc. Minerva started manufacturing a device used to treat vaginal bleeding.

Hologic sued Minerva for patent infringement. Csaba disputed the validity of the patent. Hologic moved for summary judgment, arguing that the doctrine of assignor estoppel bars Minerva from challenging the validity of the patent. Assignor estoppel applies when an invalidity defense in an infringement suit conflicts with an explicit or implicit representation made in assigning patent rights. The court agreed with Hologic and granted the motion. The issue of damages was decided by a jury.

Minerva appealed to the Federal Circuit Court and lost. Then the US Supreme Court granted certiorari and heard the case.

The Supreme Court declined to overturn decades long precedent for the doctrine of assignor estoppel. Although the Patent Act says that invalidity is a defense to infringement, the language does not abrogate the doctrine of estoppel. The Supreme Court went on to describe three situations where estoppel wouldn’t apply: (i) where there is an assignment of future inventions and an inventor cannot possibly vouch for the validity as to specific patent claims because the inventions do not yet exist; (ii) when the governing law changes so that previously valid patents become invalid under the new law; and (iii) where there is a change in patent claims.

The Supreme Court remanded the case to the Federal Circuit to address whether the third situation applied to this case. Specifically, whether any of Hologic’s new claims in the continuation is materially broader than the ones Csaba originally assigned. 

On remand, the Federal Circuit determined that the claims in the continuation patent were not materially broader than a prior patent application. So the Federal Circuit affirmed the original judgment and remanded the case to the district court for further proceedings on damages.

Why You Should Know This: Starting a new business isn’t a problem after your previous one has been acquired. Starting a new business using technology that was sold is a problem.

Case Information:    Hologic, Inc. v. Minerva Surgical, Inc., 141 S. Ct. 1068 (2021) aff’d on remand Hologic, Inc. v. Minerva Surgical, Inc., 44 F.4th 1358 (Fed. Cir. 2022)

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