Patent Term and Double Patenting

The short version

Two Federal Circuit decisions have to be read together, and reading either alone leads to an expensive mistake in opposite directions. One holds that extra term granted for Patent Office delay can expose a family member to double patenting. The other holds that in the configuration before it, a first-filed and first-issued patent set the ceiling and could not be attacked by later-filed, later-issued relatives that expire earlier.

A third page covers how the Patent Office actually applies the second one during examination, which is narrowly. None of the three is published without the others, on purpose.

Double patenting asks a narrow question: does one patent improperly extend exclusivity past a related one? The answer turns on expiration dates, and expiration dates move when the Patent Office grants extra term for its own delay.

That is where the trouble starts. In re Cellect holds the comparison uses the date after Patent Term Adjustment is added, so time granted as compensation can become the reason a relative is invalid. The instinctive response is to file terminal disclaimers across the family and align the dates.

That instinct is what Allergan exists to stop. Once a patent issues subject to a terminal disclaimer, the surrendered term is not coming back. If the patent in question is the first-filed and first-issued in its family, it sets the ceiling on exclusivity and cannot be an improper extension of anything, so disclaiming would give away term for nothing.

The two errors are mirror images. Read Cellect alone and you disclaim term you did not have to. Read Allergan alone and you skip a disclaimer you needed, past a deadline that does not reopen. Both are expensive and neither is recoverable, which is why these two pages travel together.

Three Authorities, Two Forums

What each authority decided, where it binds, and what it left open, from the three records. As of 15 August 2026.
Authority Binds What it decided What it left open
In re Cellect, Fed. Cir. 2023Courts and the OfficeObviousness-type double patenting is measured against the expiration date after Patent Term Adjustment, so term granted for Office delay can be the reason a relative is invalid; every equitable argument failedWhich family members can serve as references, which Allergan later constrained; the section 121 safe harbor, which the opinion never cites; whether the PTA and PTE distinction is stable
Allergan v. MSN, Fed. Cir. 2024Courts and the OfficeA first-filed, first-issued, later-expiring claim cannot be invalidated for double patenting over a later-filed, later-issued relativeFamilies where the later-expiring patent was also later-filed or later-issued; a contested distinctness fight (distinctness was conceded); terminal disclaimers already filed
Ex parte Baurin, Appeals Review Panel 2026, precedentialUSPTO personnel onlyAllergan applies only where the claims are first-filed, first-issued and later-expiring within a family sharing a patent term filing date; the anti-harassment rationale independently supports a rejection with no term extension in viewWhether the Federal Circuit agrees: the panel invited clarification and named In re Ablynx, No. 26-1333, as the vehicle; its proposed future framework is contingent and not current practice

The rows do not conflict. Baurin narrows how far Allergan reaches inside the Office without disturbing what the Federal Circuit held, and a litigated patent is governed by the first two rows, not the third.

The Cluster

Decision Court Decided In one line
In re Cellect Federal Circuit 28 August 2023 Extra patent term granted for Patent Office delay counts against you in a double-patenting attack.
Allergan v. MSN Federal Circuit 13 August 2024 The first patent you filed and got sets the ceiling; a later relative cannot be used to cut it short.
Ex parte Baurin USPTO Appeals Review Panel 6 August 2026 The Patent Office will apply Allergan only in a narrow configuration, and will reject for double patenting even when no patent term is being extended.
In re Cellect Time the Patent Office gives back for its own delay counts toward the expiration date used in a double-patenting comparison. The court also closed every equitable escape route. Read the Case Allergan v. MSN The first patent in a family sets the ceiling on exclusivity, so it cannot be an improper extension of anything. Filing order and issuance order decide it. Read the Case Ex parte Baurin The Patent Office will apply Allergan only in a narrow configuration, and will reject for double patenting even when no patent term is being extended. An agency decision, not a court decision. Read the Decision

The Timing Detail That Decides It

Cellect closed the escape routes a patent owner would reach for: good faith is not reviewable in that posture, and a promise never to split ownership of the family is not evidence that saves anything.

The one that matters operationally is different. A terminal disclaimer cannot be filed once a patent has expired. The remedy exists and then it stops existing, on a date that arrives whether or not anyone is tracking it. Acting reasonably does not reopen the window.

So the analysis that decides whether to disclaim has to happen while the option is still live, which in practice means well before anyone is thinking about it.

The Patent Office reads Allergan more narrowly than patent owners did. In Ex parte Baurin, a precedential agency panel held that the exception applies only where the claims are first-filed, first-issued and later-expiring in a family sharing a patent term filing date, and that this "will rarely, if ever, arise in original examination". It also held that the risk of split ownership supports a rejection on its own, with no term extension in view. That is examination practice rather than law, and the panel invited the Federal Circuit to correct it if it is wrong.

What These Pages Do Not Decide

  • Whether any particular family member is at risk. That depends on filing order, issuance order and expiration dates for the actual patents.
  • Whether to file a terminal disclaimer. It is irreversible in one direction and the deadline is unforgiving in the other.
  • Whether any continuation strategy is sound. Portfolio strategy is legal advice with consequences that cannot be walked back.
  • How a court would rule. One of these three is an agency decision that binds examiners and no judge.

Educational, not legal advice. Every quotation is verified against the court's own opinion, but a holding is not a rule about your portfolio. Consult a qualified patent attorney with the actual family in front of them.

Related

Patent Continuations A continuation turns one specification into a patent family: new claims, same priority date, no new matter. Why disclosed-but-unclaimed scope can be dedicated to the public, the copendency and term rules, the double-patenting tradeoff, and an honest read on where AI drafting helps. Read the Guide Continuation Claims A continuation is a vehicle for adaptive claiming, not adaptive disclosure. What the Federal Circuit permits when claims are drafted with a competitor's product in mind, where the original disclosure caps that reach, and what Kroy did and did not decide about asserting unadjudicated claims after an adverse IPR. Read the Reference Who Owns It, Who Invented It Ownership and inventorship are different questions with different rules, and confusing them has destroyed patents. Four decisions mark the boundaries, each read from the opinion itself. Read the Cluster What recent patent decisions add up to Thirty-one decisions, read from the opinions. The recurring theme is that patent law rewards specificity about mechanism and punishes description of results. Read the Synthesis