Summary
**Assignor estoppel** – The Supreme Court upheld the doctrine but limited its scope: it applies only when an assignor’s invalidity defense contradicts explicit or implicit representations made at the time of assignment. **Material broadening** – If an assignee later expands patent claims beyond what the assignor originally assigned, the assignor is not estopped from challenging the validity of those new, materially broader claims. **Patent Act of 1952** – The Court held that the Act did not abrogate assignor estoppel, which remains a background common-law principle. **Holding** – Vacated and remanded for the Federal Circuit to determine whether Hologic’s new claim was materially broader than the claims Truckai assigned.
Topics
Practice areas
Questions Presented
- Whether the doctrine of assignor estoppel should be abandoned or narrowed.
- Whether assignor estoppel applies when the assignor challenges a patent claim that is materially broader than the claims originally assigned.
Holdings
- Assignor estoppel applies only when the assignor's claim of invalidity contradicts explicit or implicit representations made in assigning the patent. When the new claims are materially broader than the old ones, the assignor did not warrant their validity, so estoppel does not apply.
Key quotations
“Assignor estoppel is well grounded in centuries-old fairness principles, and the Federal Circuit was right to uphold it. But assignor estoppel applies only when the assignor's claim of invalidity contradicts explicit or implicit representations he made in assigning the patent.” (5)
“If Hologic's new claim is materially broader than the ones Truckai assigned, then Truckai could not have warranted its validity in making the assignment. And without such a prior inconsistent representation, there is no basis for estoppel.” (16)
“When a person sells his patent rights, he makes an (at least) implicit representation to the buyer that the patent at issue is valid—that it will actually give the buyer his sought-for monopoly.” (13)
Factual background
Csaba Truckai invented the NovaSure System, a device to treat abnormal uterine bleeding, and assigned the patent application to Novacept, which later assigned to Hologic. Truckai later founded Minerva and developed a new, moisture-impermeable device. Hologic filed a continuation application to add a broader claim covering applicator heads generally, without regard to moisture permeability. The PTO issued the altered patent. Hologic sued Minerva for infringement. Minerva argued invalidity due to inadequate written description. Hologic invoked assignor estoppel because Truckai had assigned the original application.
Procedural history
Hologic sued Minerva for patent infringement. Minerva asserted invalidity. The District Court held that assignor estoppel barred the defense, found infringement, and awarded damages. The Federal Circuit affirmed. The Supreme Court granted certiorari.
Remand instructions
We remand this case to the Federal Circuit to now address what it thought irrelevant: whether Hologic's new claim is materially broader than the ones Truckai assigned.