Background
Obviousness-type double patenting (ODP) is a judicially created doctrine that prevents a patent owner from extending monopoly rights by obtaining a second patent on an obvious variant of an already-patented invention. In a continuation family — where a series of patent applications all claim the same priority date but issue at different times — ODP questions arise when the later-issued “child” patent expires after the originally-issued “parent.”
The patent term adjustment (PTA) system complicates things further: the USPTO must award extra days of patent term when USPTO delays in examination exceed statutory targets. Different applications in the same family can accumulate very different amounts of PTA, causing child patents to expire on different dates even from the same priority start.
Two recent Federal Circuit decisions — In re Cellect (2023) and Allergan USA Inc. v. MSN Laboratories — created uncertainty about exactly how ODP is applied when PTA is in play: which patent is the reference patent for ODP purposes, and when does a child’s expiration date improperly extend the family’s monopoly?
The Board’s Holding
The PTAB held that a child patent is not unpatentable for ODP if it does not expire later than the original (first-issued) patent in the family, including any PTA awarded to that original patent.
The key principle: the first-issued patent’s expiration date — with its own PTA baked in — sets the ceiling for the family’s maximum exclusivity window. Child patents that expire on or before that ceiling are not extending the monopoly and therefore do not raise an ODP concern, regardless of how much PTA the child patent itself has accumulated.
This resolves a critical ambiguity: the ODP analysis turns on actual expiration dates, not filing dates, issuance dates, or nominal twenty-year terms. A child patent’s PTA alone does not trigger ODP so long as the final expiration date stays within the family’s established window.
Key Takeaways
- Expiration dates control the ODP analysis. Practitioners should build expiration-date comparison charts for continuation families, accounting for all PTA across the family, rather than relying on nominal twenty-year terms from priority dates.
- Terminal disclaimers may not always be necessary. If a child patent expires before or on the same day as the first-issued family member (including that member’s PTA), a terminal disclaimer to that effect may not be required.
- Challenge examiner ODP rejections using Corteva. Examiners sometimes require terminal disclaimers in all continuations reflexively. This decision supports pushing back when the child’s actual expiration date does not exceed the family ceiling.
- Litigation risk assessment changes. Patent challengers asserting ODP invalidity must now compare actual expiration dates, not just claim the child patent has a different PTA. The bar for an ODP attack is clearer but also more fact-specific.
Why It Matters
ODP invalidity has become one of the most frequently litigated grounds in patent challenges, particularly in pharmaceutical patent families where every day of exclusivity has enormous commercial value. The Corteva decision gives patent prosecutors and litigators a clearer framework for assessing ODP risk across complex continuation families. For companies with large portfolios of continuation applications — common in pharma, biotech, and agriculture — auditing the family against the Corteva expiration-date standard is now a straightforward due diligence step.