# First Filed, First Protected: Allergan v. MSN and the Limits of Obviousness-Type Double Patenting

> The Federal Circuit held that a first-filed, first-issued, later-expiring patent claim cannot be invalidated for double patenting by a later-issued, earlier-expiring family member, rescuing patent-term adjustment.

Topic: Patents  |  Author: Lidiia Levitska  |  Source: Intellectual Property Law (outsideipcounsel.com)
Canonical: https://outsideipcounsel.com/blog/allergan-v-msn-laboratories-double-patenting-first-filed/


When a drugmaker earns extra patent life because the Patent Office dragged its feet, can a court take that bonus away by pointing to the company's own later patents? In *Allergan USA, Inc. v. MSN Laboratories Private Ltd.*, 111 F.4th 1358 (Fed. Cir. Aug. 13, 2024), the Federal Circuit said no. Writing for a panel that also included Judges Dyk and Reyna, Judge Alan Lourie held that a first-filed, first-issued, later-expiring patent claim cannot be invalidated for obviousness-type double patenting (ODP) by a later-filed, later-issued, earlier-expiring reference claim that shares the same priority date. The decision steadied an area of law that had been thrown into doubt a year earlier and preserved the value of the patent-term-adjustment system for innovators.

## At a glance

- **Case:** *Allergan USA, Inc. v. MSN Laboratories Private Ltd.*, No. 24-1061 (Fed. Cir. Aug. 13, 2024), reported at 111 F.4th 1358.
- **Court:** U.S. Court of Appeals for the Federal Circuit; opinion by Circuit Judge Lourie, joined by Judges Dyk and Reyna.
- **Posture:** Appeal from the U.S. District Court for the District of Delaware, which had held the asserted claims of the '356 patent invalid for obviousness-type double patenting in Hatch-Waxman litigation over Viberzi (eluxadoline).
- **Holding:** A first-filed, first-issued, later-expiring claim cannot be invalidated for ODP by a later-filed, later-issued, earlier-expiring reference claim having a common priority date; the panel also reversed a written-description ruling against related claims.
- **Significance:** Cabined the reach of *In re Cellect* and protected patent term adjustment, confirming that ODP polices unjustified term extension, not the foundational patent in a family.

## The drug, the family, and the timing quirk

Allergan markets Viberzi (eluxadoline) to treat irritable bowel syndrome with diarrhea; the FDA approved the drug in 2015. The compound is covered by U.S. Patent No. 7,741,356 — the "'356 patent" — which earned substantial patent term adjustment (PTA) because the Patent Office's own delays slowed its prosecution. Allergan later filed a chain of continuation applications claiming the benefit of the '356 patent's priority date. Those applications matured into several later patents that received little or no PTA and were therefore set to expire *before* the foundational '356 patent.

When generic manufacturers, led by MSN Laboratories, filed to market eluxadoline and Allergan sued, the defendants seized on that timing. They argued that the later-issued, earlier-expiring family members were proper ODP references that rendered the senior '356 patent's claims invalid — in effect, that Allergan's own continuations should claw back the term adjustment the agency had granted the parent. The district court agreed and invalidated the asserted '356 claims.

## Why the timing argument failed

Judge Lourie's opinion returned ODP to its purpose. The doctrine exists to prevent an inventor from unjustifiably *extending* the term of patent protection by obtaining a second, patentably indistinct patent that outlasts the first. That rationale, the court reasoned, does not fit a case in which the challenged patent is the first one filed and the first one issued in the family. The '356 patent "is the first-filed, first-issued patent in its family," and it does not extend the term of any later patent — its longer life comes from a statutory adjustment, not from gamesmanship.

The court rejected the view that a patent can be invalidated simply because a later-issued relative happens to expire sooner. "It is the first-filed, first-issued patent's expiration date that controls," Judge Lourie explained, and using a junior, shorter-lived continuation as the ODP reference would improperly use the doctrine to strip away PTA that Congress directed the agency to award. ODP, the panel emphasized, is concerned with the *order* and *justification* of patenting, not with which member of a family mechanically expires first.

## Distinguishing Gilead and cabining Cellect

The opinion threaded two earlier decisions. In *Gilead Sciences, Inc. v. Natco Pharma Ltd.*, 753 F.3d 1208 (Fed. Cir. 2014), the court had allowed a later-filed but earlier-expiring patent to serve as an ODP reference against an earlier-filed, later-expiring patent. Judge Lourie distinguished *Gilead* as involving patents from *different* families with different priority dates, where the later patent's earlier expiration genuinely reflected an attempt to extend term. Here, by contrast, the patents shared a common priority date and the senior patent's extra life flowed from PTA.

The panel also confronted *In re Cellect, LLC*, 81 F.4th 1216 (Fed. Cir. 2023), which had alarmed patent owners by holding that ODP is measured against a patent's PTA-*adjusted* expiration date, allowing earlier-expiring relatives to invalidate later-expiring ones. The court did not overrule *Cellect*; it distinguished it. *Cellect* addressed whether PTA counts in the expiration comparison, not whether a first-filed, first-issued patent can be the *victim* of an ODP challenge mounted with its own later continuations. Read together, the cases leave PTA vulnerable in some configurations but protect the foundational patent in a family.

## Open questions

- **How far does the "first-filed, first-issued" shield extend?** The holding turns on that specific status; patents that are neither first-filed nor first-issued in their families may still face ODP attacks measured against PTA-adjusted dates under *Cellect*.
- **What is left of *Cellect* after *Allergan*?** The two decisions coexist uneasily. Future panels must decide how to apply *Cellect*'s expiration-date comparison without letting it swallow the protection *Allergan* gives the senior patent.
- **Does the same logic reach patent term extension (PTE)?** *Allergan* concerned PTA under 35 U.S.C. § 154(b); whether identical reasoning governs Hatch-Waxman PTE under § 156 remains to be worked out.

## Implications

- **File order and issue order matter.** Whether a patent is the first-filed and first-issued member of its family can decide an ODP challenge, making prosecution sequencing a strategic variable.
- **PTA keeps its value.** Innovators can rely on the term the Patent Office adds for its own delays without fearing that their later continuations will be used to erase it.
- **ODP is about justified extension, not raw timing.** The decision reorients the doctrine around its anti-extension purpose rather than a mechanical comparison of expiration dates.
- **Generic challengers lose a tool against senior patents.** Hatch-Waxman defendants can no longer reflexively point to a brand's shorter-lived continuations to topple the foundational patent.
- **The doctrine is not dead — just narrowed.** *Cellect* still bites in other configurations, so terminal disclaimers and careful family planning remain essential.

## Frequently asked questions

**Does *Allergan v. MSN* overrule *In re Cellect*?**
No. The court distinguished *Cellect* rather than overruling it. *Cellect* allowed obviousness-type double patenting to cut down a patent's term-adjusted expiration; *Allergan* holds that the specific patent at issue — the first-filed, first-issued member of a family — cannot be the target of an ODP attack built on its own later-issued, earlier-expiring continuations.

**What is obviousness-type double patenting?**
It is a judge-made doctrine that prevents an inventor from obtaining a second patent on a claim that is not patentably distinct from a claim in an earlier patent, which would effectively extend the monopoly. It can usually be cured during prosecution with a terminal disclaimer that ties the later patent's expiration to the earlier one's.

**Why does patent term adjustment matter in this case?**
Patent term adjustment (PTA) adds time to a patent's term to compensate for delays the Patent Office caused during prosecution. Because the foundational '356 patent earned substantial PTA, it expired after its own later-filed continuations — the unusual timing that set up the double-patenting fight.

## Authorities and sources

- Federal Circuit opinion (Aug. 13, 2024), No. 24-1061: https://www.cafc.uscourts.gov/opinions-orders/24-1061.OPINION.8-13-2024_2366074.pdf
- FindLaw case page, *Allergan USA, Inc. v. MSN Laboratories Private Ltd.*: https://caselaw.findlaw.com/court/us-federal-circuit/116478532.html
- Gibson Dunn, "Federal Circuit Decision in Allergan v. MSN": https://www.gibsondunn.com/federal-circuit-decision-in-allergan-v-msn/
- White & Case, "Federal Circuit Limits the Application of Obviousness-Type Double Patenting for Patents in the Same Family": https://www.whitecase.com/insight-alert/federal-circuit-limits-application-obviousness-type-double-patenting-patents-same
- Patently-O, "Allergan: En Banc Support for Stronger ODP Rules": https://patentlyo.com/patent/2024/10/allergan-support-stronger.html