Under US patent law, an inventor is entitled to only one patent for an invention. Thus, the US Patent Office can reject a patent application based on double-patenting. Note also that double-patenting can be used as a defense to a claim of patent infringement. Essentially, the defendant can argue that the patent allegedly infringed is invalid based on double patenting. See, for example, Perricone v. Medicis Pharm. Corp., 267 F.Supp.2d 229 (D.Conn.2003) aff’m on the double patenting issue, 432 F. 3d 1368 (Federal Circuit 2005).

This article addresses options for responding to a rejection by the US Patent Office based on double patenting.

Note that with respect to double patenting, the issue applies only to an inventor with more than one patent. When considering double patenting as a basis for rejection — or invalidity — the focus is between an earlier patent and a later patent or application owned or submitted by the same inventor.

Two types of double patenting

There are two types of prohibited double patenting: statutory and non-statutory. The first involves patent claims that are identical between the two patents. This is prohibited by §101 of the Patent Act. As such, this is called statutory double-patenting. If your patent application is rejected for statutory double patenting, essentially, there are only three options:

• Cancel or abandon your application
• Modify the claims in the pending application or
• Dispute the rejection and potentially litigate

The final option might be viable if the Patent Examiner is wrong. Rejection for statutory double patenting will be forthcoming if the patent claims are word-for-word the same. But, if there is a slight variation in the wording, that variation might be sufficient to avoid a rejection for double-patenting.

Non-statutory double patenting is often designated as “obviousness-type” double patenting. That is, the two patent claims are not worded the same, but nonetheless are so alike that granting the application would effectively be granting two patents. With non-statutory double patenting, the public policy purpose is to disallow an inventor from extending the life of the patent protection provided by the earlier patent. If your patent application is rejected for non-statutory double patenting, the three options from above are available.

A fourth  option for non-statutory double patent rejection is to file a “Terminal Disclaimer.” Essentially, this is an inventor’s agreement that the term of the second patent’s protection will not exceed the term of the earlier patent. As an example, the term of protection for a utility patent is 20 years. If a Terminal Disclaimer is filed, the Patent Office will also require that the patents be owned by the same person/entity during the relevant time period. By its terms, a Terminal Disclaimer is binding upon the inventor and any successors or assigns.

For more information or if you have an invention that you want to patent, contact the patent lawyers at Revision Legal at 231-714-0100.

The Legal Standard for Obviousness-Type Double Patenting

Obviousness-type double patenting (“ODP”) is a judicially-created doctrine that prevents inventors from extending their patent monopoly by obtaining a second patent on obvious variations of an already-patented invention. The Federal Circuit has consistently held that ODP exists to prevent an inventor from effectively extending the patent term by staggering multiple patent applications that claim trivially different variations of the same core invention.

The analysis for ODP involves a two-step inquiry. First, the court or examiner must construe the claims of the earlier patent and the later application. Second, it must determine whether the claims of the later application are patentably distinct from the claims of the earlier patent. Claims are not patentably distinct if the differences between them would have been obvious to a person of ordinary skill in the relevant art at the time the later application was filed. This is the same standard used for a conventional obviousness rejection under 35 U.S.C. § 103, applied in a one-way or two-way direction depending on the procedural context.

Terminal Disclaimers: Strategic Considerations

While a Terminal Disclaimer is the most common tool for overcoming an ODP rejection, it carries strategic implications that must be carefully considered before filing one:

• Loss of patent term — A Terminal Disclaimer disclaims any patent term extending beyond the expiration date of the earlier patent. If the earlier patent expires in 2030 and the later application issues in 2025 with a normal 20-year term running to 2045, the Terminal Disclaimer cuts the later patent’s effective term to 2030 — a loss of 15 years of protection.
• Common ownership requirement — A Terminal Disclaimer typically requires that both patents remain commonly owned throughout the period of enforcement. If the patents are later assigned to different entities — for example, in a partial technology sale or license — the Terminal Disclaimer may render the later patent unenforceable.
• Impact on patent family valuation — In patent licensing and M&A transactions, a Terminal Disclaimer signals to sophisticated buyers and licensees that one patent in the family is constrained by another. This can affect portfolio valuation and license negotiations.
• Invalidity risk — A Terminal Disclaimer creates a formal link between two patents. Courts have held that if a Terminal Disclaimer is found to be defective or if the common ownership requirement is violated, the later patent may be unenforceable. In some cases, invalidity of the reference patent has been found to affect the disclaimed patent as well.

Double Patenting as an Invalidity Defense

When a patent owner brings an infringement suit, accused infringers frequently review the plaintiff’s entire patent portfolio looking for double patenting issues that were not caught during prosecution or that arose after prosecution through portfolio restructuring. An ODP invalidity defense can be raised against an issued patent even if the patent examiner did not raise it during examination. This is because ODP is a defense to enforcement, not merely a prosecution issue.

Courts have found patents invalid for ODP where the patent owner failed to file a Terminal Disclaimer and where the claims of two patents in a family were patentably indistinct. Defendants have successfully invalidated commercially significant patents on this ground. Patent owners should therefore proactively audit their patent portfolios for potential ODP issues before asserting patents in litigation.

Recent Developments: The In re Cellect Decision

The Federal Circuit’s 2023 decision in In re Cellect, LLC, 81 F.4th 1216 (Fed. Cir. 2023), clarified that Patent Term Adjustment (“PTA”) — the additional patent term granted to compensate for USPTO examination delays — does not protect a patent from an ODP challenge. Prior to Cellect, some practitioners believed that PTA-extended patents could survive ODP challenges because the extended term resulted from government delay rather than inventor gamesmanship. The Federal Circuit rejected this argument, holding that ODP applies to PTA-extended patents and that a Terminal Disclaimer must be filed to overcome the rejection regardless of whether the extended term results from PTA or from the normal patent term.

The Cellect decision has significant implications for pharmaceutical and biotech patent owners who frequently rely on PTA to compensate for lengthy examination timelines. If you hold patents with PTA-extended terms and related patents or applications in the same family, a portfolio review for ODP exposure is advisable.

Contact the patent lawyers at Revision Legal at 231-714-0100 to discuss responding to a double patenting rejection or auditing your patent portfolio for ODP risk.