Filing a continuation application from a parent patent is an implicit admission that obviousness-type double patenting (ODP) applies to the resulting continuation patent. A Terminal Disclaimer in the continuation patent over the parent patent is thus necessary to avoid the public policy concerns underlying ODP. This is supported by statute, case law, and practice. For example, 35 U.S.C. § 101 provides an applicant is entitled to “a patent” for each invention, the parent patent. Moreover, a continuation patent is not entitled to the safe harbor protection reserved for a divisional patent under 35 U.S.C. § 121. And for more than 25 years, the Federal Circuit has relied on the public policy concerns underlying ODP to invalidate continuation patents challenged for ODP over the parent patent. Accordingly, any continuation application filed from a parent patent is an implicit admission that ODP applies to the resulting continuation patent. 

A Continuation Patent is Not “A Patent” Under Section 101

The limit of Section 101 to “a patent” for each invention is well recognized within the case law, and does not extend to a continuation patent issuing from a parent patent. “A crucial purpose of ODP is to prevent an inventor from securing a second, later-expiring patent from non-distinct claims.”  In re Cellect, LLC, 81 F.4th 1216, 1226 (Fed. Cir. 2023), petition for rehearing en banc denied. “[Section 101] permits only one patent to be obtained for a single invention.” In re Lonardo, 119 F.3d 960, 965 (Fed. Cir. 1997). The USPTO’s perspective on this issue was recently clarified in In re Cellect, Director’s Response to Cellect, LLC’s Petition for Rehearing En Banc, at 1 (December 14, 2023), where it noted that “[Section 101] entitles an inventor to ‘a patent’ – a single patent – for an invention.” Thus, a continuation patent is not “a patent” under Section 101, and so is subject to ODP over the parent patent.

In the absence of a restriction requirement, a parent application is considered to be drawn to a single invention irrespective of how many inventions are claimed. Because the issuance of a restriction requirement is at the discretion of the examiner, filing a parent application with multiple inventions forfeits Applicant’s ability to argue that the different inventions are separately patentable when no restriction requirement is issued. Alternatively, an Applicant can file separate applications to the different inventions where the separate applications do not share a priority claim. Each separate application is, thus, “a patent” to the invention claimed and minimizes the risk of ODP between the separate applications.

A Continuation Patent is Not Entitled to the Benefit of the Safe Harbor Provision

The safe harbor provision of Section 121 also provides no protection for the continuation patent, as Section 121 is limited to “a divisional” patent. In addition to filing under Section 121, a divisional application must be filed “as a result” of an earlier restriction requirement, must have common lineage with the application in which the restriction requirement issued, and must be filed with claims that have consonance (i.e., claims are drawn to one or more of the non-elected inventions, without overlap with the claims in the parent patent, and were subject to the restriction requirement in the parent patent). A continuation application filed under Section 120, but meeting all other requirements of a divisional application, does not meet the requirements of being a divisional application. “Because the … applications were filed as continuation applications instead of divisional applications, we hold that the [resulting] patents do not receive the protections afforded by § 121’s safe harbor.”  Amgen v. Roche, 580 F.3d 1340, 1354 (Fed. Cir. 2009). Thus, a continuation application drawn to subject matter that is separately patentable from the subject matter of the parent patent is vulnerable to an obviousness-type double patenting rejection from the USPTO and later patent challenge. 

A continuation application can, however, be designated a divisional application up to grant of the patent, and benefit from the safe harbor provision, assuming it otherwise meets the requirements for a divisional application. “For a challenged patent to receive safe-harbor protections, the application must be properly designated as a divisional application, at the very latest, by the time the challenged patent issues on that application.” In re Janssen Biotech, Inc., 880 F.3d 1315, 1323 (Fed. Cir. 2018). In contrast to a continuation patent, such a divisional patent is deemed “a patent” under Section 101 for the invention claimed, and so is not in conflict with Section 101. 

The Federal Circuit Invalidates Continuation Patents Over Parent Patents

Failure to designate an application as a divisional has resulted in invalidation of the resulting continuation patent by the Federal Circuit. For at least the last 25 years, the Federal Circuit has invalidated continuation patents challenged for ODP. See, for example, In re Lonardo (1997), Pfizer, Inc. v. Teva Pharmaceuticals, 518 F.3d 1353 (Fed. Cir. 2008), Amgen v. Roche, 580 F.3d 1340 (Fed. Cir. 2009), St. Jude Medical, Inc. v. Access Closure, Inc., 729 F.3d 1369 (Fed. Cir. 2013), AbbVie Inc. v. Mathilda & Terence Kennedy Inst. Of Rheumatology Trust, 764 F.3d 1366 (Fed. Cir. 2014), In re Hitachi Metals, Ltd., 603 Fed.Appx. 976 (Fed. Cir. 2015), GD Searle LLC v. Lupin Pharmaceuticals, Inc., 790 F.3d 1390 (Fed. Cir. 2015), In re Janssen Biotech, Inc., 880 F.3d 1315 (Fed. Cir. 2018), and most recently In re Cellect (2023). These outcomes are expected in view of the public policy concerns underlying ODP: unjustified timewise extension of patent term; and avoiding multiple lawsuits by different parties on substantially the same invention. In re Longi, 759 F.2d 887, 892 (Fed. Cir. 1985). “Fundamental to this doctrine is the policy that: ‘[t]he public should … be able to act on the assumption upon the expiration of the patent it will be free to use not only the invention claimed in the patent but also modifications or variants which would have been obvious to those of ordinary skill in the art at the time the invention was made.’”  In re Longi, 892-3, citing In re Zickendraht, 319 F.2d 225, 232 (CCPA 1963) (Rich, J., concurring), emphasis in original. See also Singer Mfg. Co. v. June Mfg. Co., 163 U.S. 169, 185 (1896). Without the protection of the safe harbor provision, these public policy concerns apply to all continuation applications and patents filed from a parent patent.

The recent In re Cellect decision highlights these points. In re Cellect involved an appeal of a decision by the Patent and Trademark Appeal Board (PTAB) invalidating a continuation patent for ODP over the parent patent, where the continuation patent expired later than the parent patent due to an award of patent term adjustment under Section 154. No terminal disclaimer was filed during prosecution of the continuation application in Cellect, and no ODP rejection was made by the examiner. Cellect did not argue that the claims of the continuation patent were patentably distinct from the subject matter of the parent patent, or that the continuation patent was “a patent” under Section 101. Moreover, Cellect did not argue that the continuation patent was entitled to the protection of the safe harbor provision reserved for divisional applications. In its request for a rehearing en banc, Cellect instead argued that the absence of a rejection by the examiner for ODP over the parent patent wrongly imposes an obligation on the patent owner “to file a preemptive terminal disclaimer.” Cellect, LLC’s Petition for Rehearing En Banc, at 16 (November 13, 2023). The Federal Circuit rejected this argument, holding that failure by the examiner to raise the issue of ODP during prosecution of the continuation application does not remove the burden on the patent owner to address ODP. “[I]t would frustrate the clear intent of Congress for applicants to benefit from their failure, or an examiner’s failure, to comply with established practice concerning ODP, which contemplates terminal disclaimers as a solution to avoid invalidation of patents claiming obvious inventions.” In re Cellect, at 1229. 

As discussed in our recent comments regarding In re Cellect, it is important for patent owners to address ODP, even unsolicited, during prosecution, either by filing a preemptive terminal disclaimer or by filing a divisional application and qualifying for the safe harbor provision under Section 121 (Cuomo, et al., “Federal Circuit Puts the Onus on Patent Owners to Disclaim Patent Term or Face Double-Patenting”, 2023). If not filed during prosecution of the application, a terminal disclaimer over the parent patent can be filed only if the reference patent has not yet expired. “With obviousness-type double patenting, … a terminal disclaimer may overcome that basis for unpatentability, assuming that the first patent has not expired.” Boehringer Ingelheim v. Barr, 592 F.3d 1340, 1348 (Fed. Cir. 2010), emphasis in Boehringer, citing In re Lonardo, at 965. Whether filed during pendency of the continuation application, or after the continuation patent has granted, a terminal disclaimer over the parent patent is required to address the ODP inherent to a continuation application and patent.

Despite the ODP inherent in a continuation, filing a continuation application is a suitable strategy to pursue additional claims. In doing so, the applicant recognizes the resulting continuation patent is not “a patent” under Section 101, and is not subject to the safe harbor provision of Section 121. The continuation is therefore subject to ODP and a terminal disclaimer will be required over the parent patent, whether filed during prosecution of the continuation application or after grant and before expiration of the parent patent. A terminal disclaimer over the parent patent can be avoided by satisfying the requirements of a divisional application, where the divisional application is filed from a parent application with claims structured to trigger a restriction requirement. Alternatively, the Applicant can file separate applications to the different inventions where the separate applications do not share a priority claim, thus minimizing the risk of ODP. But in the absence of such a dual-filing strategy, and the absence of a restriction requirement and subsequent divisional application, a continuation application filed from a parent patent is an implicit admission that ODP applies to the resulting continuation patent.