Practice Tips for Avoiding Terminal Disclaimers and Maintaining PTA

By Leslie A. McDonell and Christina M. Rodrigo

©2017. Published in Landslide, Vol. 10, No. 2, November/December 2017, by the American Bar Association. Reproduced with permission. All rights reserved. This information or any portion thereof may not be copied or disseminated in any form or by any means or stored in an electronic database or retrieval system without the express written consent of the American Bar Association or the copyright holder.

The doctrine of obviousness-type double patenting (OTDP) was developed when US patents had a 17-year patent term. Because that patent term ran from the patent issue date, the filing of continuation applications on obvious variants of a previously claimed invention had the potential to extend the patent monopoly for the invention. The doctrine of OTDP was originally intended to prevent this result by requiring terminal disclaimers of later, commonly owned patents that did not claim patentably distinct subject matter over the earlier issued patents. Thus, in theory at least, all commonly owned patents that relate to a single invention or its obvious variants would have a single expiration date. Because the patent term is now 20 years from the first nonprovisional filing date, later-filed continuations and divisionals will expire on the same date as a parent patent, unless a patent is awarded patent term adjustment (PTA) from United States Patent and Trademark Office (USPTO) delays. This article will discuss practice tips to avoid filing terminal disclaimers that could reduce or eliminate PTA and shorten the patent term.

Restriction requirements issued by the USPTO require an applicant to divide independent and patentably distinct claims into separate applications instead of pursuing all of the claims in a single application.1 To address the potential injustice created by inconsistent standards imposed by examiners in restriction requirements and courts evaluating OTDP, Congress enacted 35 U.S.C. § 121 to provide a safe harbor for claims that must be filed in separate applications due to restriction requirements issued by the USPTO. The safe harbor provision states:

A patent issuing on an application with respect to which a requirement for restriction under this section has been made, or on an application filed as a result of such a requirement, shall not be used as a reference either in the Patent and Trademark Office or in the courts against a divisional application or against the original application or any patent issued on either of them, if the divisional application is filed before the issuance of the patent on the other application.2

Thus, if the USPTO issues a restriction between claims, patents issuing on the restricted claim groups cannot be applied against each other for OTDP. Making sure that the safe harbor provisions of 35 U.S.C. § 121 apply to your claims will avoid the necessity of filing a terminal disclaimer and risking the loss of PTA to overcome an OTDP problem. As you might expect, it is not always simple to do so, and a few key requirements must be met.

First, it is important to ensure that all of the subject matter that you may want to claim in an application is presented in the original claims subject to restriction by the USPTO. The Federal Circuit has held that an application claiming subject matter that was not part of the claims subject to restriction may not be protected by the safe harbor of § 121.3 For example, if you receive a restriction requirement between claims to compositions and claims to methods of treatment, but later pursue claims to diagnostic assays involving the compositions, you are very likely to be required to file a terminal disclaimer unless you can establish that the diagnostic claims are patentably distinct from the composition claims and/or method of treatment claims. On the other hand, if the diagnostic claims had been present in the originally restricted claims, this subject matter would very likely have been restricted into a separate group and the safe harbor protections of 35 U.S.C. § 121 would apply.

It can be difficult to include all subject matter in the originally filed claims for purposes of the restriction requirement, at least in part due to the high cost of excess claims, but also because certain embodiments of the original specification may not emerge as important subject matter to claim at the time the original application is filed. It is not entirely clear how literally the courts will apply the requirement for all subject matter to be present in the claims subject to restriction in order to preserve safe harbor protection. Consider this scenario: an application describes and claims a genus of compounds and multiple methods of treatment (rationally related to the mechanism of action of the compounds), but for one or both of the reasons provided above, not all of the treatments supported in the specification were recited in the presented claims. A restriction requirement is issued between claims to (1) compounds and (2) methods of treatment, without specifying any particular diseases. It is not clear from the case law whether the safe harbor protection (from the parent patent claiming the compounds) would be extended to all methods of treatment because the restriction was drawn generally—or only to those treatments that were specifically recited in the restricted claims. Arguments on both sides of the issue are compelling. Arguably, claims to additional methods of treatment follow the lines of demarcation in the restriction requirement and maintain consonance. However, courts often apply a strict test for the application of § 121 because they tend to view any extension of the patent term as a “potential windfall” to the patentee.4 As a result, the only way to ensure § 121 protection for PTA accrued in a divisional application is to make sure that the claims subject to restriction are as inclusive as possible.

Second, once you have received a restriction requirement, at least one divisional application must be filed before the issuance of the application in which the restriction was given, and the divisional claims must maintain consonance with the original restriction requirement.5 It’s not necessary, however, for all divisional applications to be filed before the issuance of the originally restricted application; serial divisional applications are afforded safe harbor protection.6 Nor is it necessary to file separate applications to each of the restriction groups to ensure safe harbor protection, as long as the lines of demarcation drawn by the examiner in the original restriction requirement are maintained.7 In other words, claims from different restriction groups may be combined, but claims from the same restriction group should not appear in different applications.

The courts have made clear that the § 121 safe harbor also applies to continuing applications deriving from a divisional application filed as a result of a restriction requirement, and even intervening continuation applications do not render a later patent ineligible for § 121 protection so long as they descend from a divisional application filed as a result of a restriction requirement.8 However, the § 121 safe harbor will not protect patents descending exclusively from continuation applications.9 Nor will continuation-in-part (CIP) applications be afforded § 121 safe harbor, even if the claims of the CIP are consonant with an original restriction in a parent or grandparent application.10 Additionally, a change in the designation of a continuation or CIP to a divisional to recapture § 121 protection is an error not correctable by reissue.11

Developing a thoughtful claim strategy before prosecution begins and filing timely divisional applications are essential parts of your strategy to ensure that your applications receive safe harbor protection from OTDP to avoid loss of PTA.


1. U.S. Patent & Trademark Office, Manual of Patent Examining Procedure (MPEP) § 803 (9th ed. Rev. 7, Nov. 2015).

2. 35 U.S.C. § 121.

3. See Geneva Pharm., Inc. v. GlaxoSmithKline PLC, 349 F.3d 1373, 1379 (Fed. Cir. 2003) (holding that § 121 did not shield the patent at issue from double-patenting invalidity because the method of use claims in the patent at issue were never pending in the original application; to protect a patent from a double-patenting rejection, § 121 requires that the claims later sought to be shielded must be entered in a parent application before a restriction requirement is issued).

4. G.D. Searle LLC v. Lupin Pharm., Inc., 790 F.3d 1349, 1354 (Fed. Cir. 2015) (quoting Geneva Pharm., 349 F.3d at 1382).

5. St. Jude Med., Inc. v. Access Closure, Inc., 729 F.3d 1369, 1377 (Fed. Cir. 2013); Amgen Inc. v. F. Hoffman-La Roche Ltd, 580 F.3d 1340, 1354 (Fed. Cir. 2009) (holding that a patent descending from a continuation application that could have been properly designated as a divisional does not receive § 121 protection).

6. Boehringer Ingelheim Int’l GmbH v. Barr Labs., Inc., 592 F.3d 1340, 1351 (Fed. Cir. 2010) (“§ 121 refers broadly to ‘a divisional application,’ and does not state that the divisional must be a direct divisional of the original application”).

7. Id. at 1353–54.

8. Symbol Techs., Inc. v. Opticon, Inc., 935 F.2d 1569, 1579–81 (Fed Cir. 1991).

9. Amgen, Inc., 580 F.3d at 1354; Ex Parte Sauerberg, No. 2015-007064 (P.T.A.B. Jan. 10, 2017) (holding that a divisional application first filed after two consecutive continuation applications off of the application in which the restriction was issued is not entitled to § 121 safe harbor because “[t]he safe harbor provision expressly states that it only applies ‘if the divisional application is filed before the issuance of the patent on the other application’”).

10. Pfizer, Inc. v. Teva Pharm. USA, Inc., 518 F.3d 1353, 1361 (Fed. Cir. 2008).

11. G.D. Searle LLC v. Lupin Pharm., Inc., 790 F.3d 1349, 1354–55 (Fed. Cir. 2015).

Leslie A. McDonell

Leslie A. McDonell is a partner at Finnegan. She specializes in intellectual property matters for the biotechnology and pharmaceutical industries.

Christina M. Rodrigo

Christina M. Rodrigo is an associate at Finnegan in Boston, Massachusetts. She focuses on patent prosecution and due diligence for innovative pharmaceutical clients.