Patents

In re Cellect: When Patent Term Adjustment Meets Double Patenting

The Federal Circuit held that obviousness-type double patenting is measured against a patent's post-PTA expiration date, reshaping prosecution strategy for patent families.

March 18, 2026
Image sensor wafer under inspection in a semiconductor fabrication facility
The Cellect patents covered solid-state image sensors; the dispute turned on patent term, not technology. Shutterstock
Educational content, not legal advice. This article explains general legal concepts. It does not create an attorney–client relationship. For your specific situation, consult a licensed attorney.

In In re Cellect, LLC, No. 22-1293 (Fed. Cir. Aug. 28, 2023), a panel of Circuit Judges Lourie, Dyk, and Reyna — in an opinion authored by Judge Lourie — confronted a question that the court had never squarely answered: when a patent’s term is extended by patent term adjustment (PTA) for U.S. Patent and Trademark Office (USPTO) delay, is the resulting later expiration date measured against earlier-expiring family members for obviousness-type double patenting (ODP)? The court answered yes. The decision affirmed the Patent Trial and Appeal Board across a set of ex parte reexaminations and held that a claim entitled to a longer term solely because of PTA can be invalidated for ODP over a commonly owned, earlier-expiring relative. The Supreme Court declined to disturb that result, denying certiorari in Cellect LLC v. Vidal, No. 23-1231, on October 7, 2024.

The holding is deceptively narrow in its statutory mechanics but sweeping in its practical reach. It converts what many prosecutors treated as a “free” extension — extra days awarded to compensate for the agency’s own administrative lag — into a potential liability that can shorten or invalidate later-issued claims in a portfolio. For anyone managing a continuation-heavy family, Cellect rewired the calculus around terminal disclaimers.

At a glance

  • Case: In re Cellect, LLC, No. 22-1293 (Fed. Cir. Aug. 28, 2023); cert. denied sub nom. Cellect LLC v. Vidal, No. 23-1231 (Oct. 7, 2024).
  • Panel: Lourie (author), Dyk, Reyna.
  • Posture: Appeal from PTAB decisions in five ex parte reexaminations; the Board sustained ODP rejections of U.S. Patent Nos. 6,424,369; 6,452,626; 6,982,742; and 7,002,621, each of which had received PTA. The reference patent in the family, U.S. Patent No. 6,862,036, received no PTA.
  • Technology: Solid-state image sensors for portable communication devices — but the patents shared a common priority chain, so they would have expired on the same day but for PTA.
  • Holding: ODP for a patent that has received PTA is evaluated against the expiration date after PTA is added. A claim that expires later only because of PTA can be invalidated for ODP over an earlier-expiring family member absent a timely terminal disclaimer.
  • Key distinction: PTA under 35 U.S.C. § 154(b) is treated differently from patent term extension (PTE) under § 156.

How the case arose in prosecution and reexamination

The Cellect patents descended from a common application and shared a single priority date. Under the post-1995 regime, that meant they would ordinarily share a single twenty-years-from-filing expiration date. Four of the patents, however, carried PTA awarded under § 154(b) to compensate for USPTO prosecution delays, pushing their expirations past that of the reference patent, the ‘036, which received none. None of the four PTA-bearing patents was subject to a terminal disclaimer.

Cellect asserted the patents in litigation, which prompted the accused infringer to seek ex parte reexamination. The examiner concluded — and the PTAB agreed — that the PTA-extended claims were unpatentable for ODP over the earlier-expiring family members. The double-patenting rejections did not rest on any new prior art in the conventional sense; they rested on the temporal gap that PTA had introduced between otherwise patentably indistinct claims. Because the patents had already expired by the time of the appeal, terminal disclaimers were no longer available as a cure, which sharpened the stakes: the question was not how to fix the problem but whether the problem existed at all.

The obviousness-type double patenting analysis

ODP is a judicially created doctrine that prevents an applicant from securing a second, later-expiring patent on an invention that is not patentably distinct from a first. Its historical purpose is twofold: to bar an unjustified extension of the right to exclude, and to prevent harassment by multiple assignees asserting essentially the same invention. The conventional cure is a terminal disclaimer under 37 C.F.R. § 1.321, which surrenders any term of the later patent extending beyond the earlier one and ties the two together in ownership.

The contested premise in Cellect was which expiration date counts. Cellect argued that the ODP comparison should be made against the patents’ “natural” twenty-year expiration — the date the family would have shared absent any agency delay — so that PTA, a statutory entitlement, would sit on top of an already-valid term. The Federal Circuit rejected that framing. The court held that the relevant date is the actual expiration date, PTA included. In its words, the expiration date used for an ODP analysis where a patent has received PTA is the expiration date after the PTA has been added. Because the four patents expired later than the ‘036 only by virtue of PTA, and because their claims were not patentably distinct, they fell to ODP.

That reasoning reflects a continuity with Gilead Sciences, Inc. v. Natco Pharma Ltd., 753 F.3d 1208 (Fed. Cir. 2014), which untethered ODP from issuance order and anchored it to expiration dates in the post-URAA world. Cellect extends that logic one step: if expiration date is the metric, then PTA — which by definition moves the expiration date — must be part of the comparison.

Patent term adjustment under § 154(b) versus extension under § 156

The most consequential analytical move in Cellect is the court’s refusal to treat PTA like PTE. In Novartis AG v. Ezra Ventures LLC, 909 F.3d 1367 (Fed. Cir. 2018), the court had held that a § 156 patent term extension — the Hatch-Waxman compensation for regulatory review delay — is not curtailed by ODP. Cellect argued that PTA deserved the same immunity.

The panel disagreed, grounding the difference in statutory text and structure. Section 156 and § 154(b) “are dealt with in different statutes and deal with differing circumstances,” the court reasoned. Section 156 contains its own provisions governing how extended term interacts with other patents and expressly contemplates extension as an overlay on an otherwise-determined term. Section 154(b), by contrast, includes language tying PTA to the patent’s term and, critically, provides that no PTA shall extend a patent’s term beyond a date specified in a filed terminal disclaimer. The court read that disclaimer carve-out as a textual signal that Congress expected PTA to be subordinate to ODP-driven terminal disclaimers — not insulated from them. The upshot: PTE can rescue term that ODP would otherwise cut, but PTA cannot.

This is the holding with the longest reach. It means the same earned-extension mechanic produces opposite results depending on its statutory source, and it places the burden squarely on the patent owner to disclaim term during prosecution rather than rely on the adjustment surviving a later validity attack.

Open questions

  • Patentable distinctness as a backstop. Cellect resolved when ODP applies, not whether the particular claims were patentably indistinct. A family member that is genuinely distinct remains immune, so the merits of the obviousness comparison still matter and remain litigable case by case.
  • Timing of the disclaimer. The decision leaves unsettled how courts will treat terminal disclaimers filed late — during litigation or reexamination — versus during original prosecution, and whether an expired patent can ever be cured.
  • Interaction with the USPTO’s proposed terminal-disclaimer rulemaking. The agency’s subsequent efforts to condition terminal disclaimers on enforceability tie-bars add a second layer of risk that Cellect did not address.
  • Common-ownership edge cases. The doctrine’s reach across patents that share priority but diverge in ownership through assignment remains a live area.

Implications

  • Audit PTA-bearing families now. Any portfolio with multiple patents off a common priority chain, where some members carry PTA and others do not, is exposed. Identify the earliest-expiring relative — it sets the ceiling.
  • File terminal disclaimers proactively, not reactively. Because the cure must generally be in place before expiration, treat the disclaimer decision as a prosecution-stage task, weighing the value of extra term against the risk of total invalidation.
  • Distinguish, where you can. The strongest defense is that claims are patentably distinct; draft and prosecute later family members with an eye to genuine differentiation rather than relying on PTA to preserve term.
  • Model term loss in valuation and licensing. PTA can no longer be assumed durable; diligence on acquired portfolios should stress-test the latest-expiring claims against earlier family members.
  • PTE remains the safer harbor. For regulated products, § 156 extension still enjoys the Novartis immunity, so the strategic value of securing PTE — as opposed to leaning on PTA — has increased.

Frequently asked questions

Does Cellect mean every patent with PTA is invalid? No. The decision only matters where an earlier-expiring, commonly owned family member contains claims that are not patentably distinct. A standalone patent, or one whose relatives are genuinely different, is unaffected. PTA itself remains valid; the issue is the comparison against relatives.

Can a terminal disclaimer still fix the problem? Often, but timing is everything. A terminal disclaimer filed while the patents are alive can align expiration dates and defeat the ODP theory. In Cellect itself the patents had already expired, foreclosing that cure. The lesson is to disclaim during prosecution rather than gamble on surviving a later challenge.

Why is patent term extension treated differently from patent term adjustment? The court grounded the split in the statutes themselves. Section 156 (PTE) operates as an overlay with its own interaction rules and was held immune from ODP in Novartis AG v. Ezra. Section 154(b) (PTA) expressly subordinates the adjustment to any filed terminal disclaimer, which the Federal Circuit read as Congress’s signal that PTA, unlike PTE, yields to ODP.

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