The doctrine of Obviousness-Type Double Patenting (ODP) is a judicially created doctrine whose aim is to prevent the unjustified patent term extension arising from claims that are not patentably distinct having different expiry dates. This doctrine arose in the era of U.S. Patent law when the term of a patent was calculated from the issue date of the patent. In that era, it was possible for multiple patents, which claim the same priority, to have different expiration dates because of their different grant dates. To overcome an ODP rejection, applicants are required to file a Terminal Disclaimer, disclaiming the term of the later-issued patent that would extend beyond the term of the earlier-issued patent. Without the doctrine of ODP and the required Terminal Disclaimer, applicants could have "gamed" the system by engaging in tactics to delay the issuance of continuation applications to get later expiration dates for claims that are not patentably distinct from earlier expiring claims.

However, the potential to game the system was largely removed when the law for calculating patent term changed with the Uruguay Round Agreements Act (URAA). For patent applications filed on or after June 8, 1995, the term of an issued patent is 20 years from the filing date of the earliest non-provisional application to which priority is claimed. For applications filed on or after June 8, 1995, only two provisions exist in the patent statute that extend the term beyond these 20 years: Patent Term Adjustment (PTA) and Patent Term Extension (PTE). PTA compensates patentees for delays caused by the U.S. patent office during prosecution, whereas PTE compensates patentees for the patent term that is lost while the patentee is awaiting regulatory approval of the safety and efficacy of the product (i.e. FDA approval).

Even though it is much more difficult for applicants to "game" the system to get extra term in post-1995 applications in the same way as before (i.e. by deliberately delaying the issuance of a continuation application as a patent), the courts, and the USPTO continue to apply the doctrine of ODP when they find that there is an unjustified extension of patent term. As discussed below, the Federal Circuit has clarified the contours of the ODP doctrine in two recently issued decision, however a key question regarding how the doctrine applies to parent-child ODP remains unsettled.
In Novartis AG v. Ezra Ventures LLC, No. 2017-2284 (Fed. Cir. Dec. 7, 2018), the Federal Circuit clarified that PTE is not an unjustified extension of term and that a patent with added term solely attributable to PTE would not be held invalid for ODP over a reference patent having an original expiration that was the same as, or later, then the PTE-extended patent’s original expiration.

Further, in Novartis Pharms. Corp. v. Breckenridge Pharm. Inc., Nos. 2017-2173, 2175-2180, 2182-2184 (Fed. Cir. Dec. 7, 2018), the Federal Circuit clarified that because the law for calculating patent term expiration dates changed on June 8, 1995, a later-filed, earlier-expiring, post-URAA patent cannot serve as a double patenting reference for an earlier-filed, later-expiring, pre-URAA patent.

However, one particular scenario where substantial uncertainty remains, is when two (or more) patents share the same priority, but the earlier-issued patent has more days of PTA. This is a common scenario and can happen, for example, when the earlier application was the subject of a successful appeal (which typically accrues significant PTA). Follow-on continuations are often granted much more quickly, and therefore have far less PTA, because they can rely on the rationale that supported allowance of the parent patent.

Since the patent term of the later-issued patent is shorter, a Terminal Disclaimer filed in the later-issued patent (over the term of the later-expiring earlier-issued patent) would not shorten its term. However, in Gilead Sciences, Inc. v. Natco Pharma Ltd., 753 F.3d 1208, 1217 (Fed. Cir. 2014), the Federal Circuit held that an earlier-issued, but later-expiring patent, could be held invalid for ODP in view of a later-issued, but earlier-expiring reference patent. In that case, the two patents in question were both filed after June 8, 1995 but did not share the same priority. Instead, the patents or patent applications had different earliest non-provisional filing dates and therefore different expected expiration dates. Although the Federal Circuit in Gilead qualified its holding as applying “under the circumstances of this case,” at least one District Court has extended Gilead's logic to the scenario outlined above, where an earlier-expiring child patent is used to shorten the term of a later-expiring parent patent. See Magna Electronics, Inc. v. TRW Automotive Holdings Corp., No. 1:12-cv-654; 1:13-cv-324 (Dec. 10, 2015). Since Magna and TRW settled their litigation, practitioners and patentees will have to wait for another case to determine whether the PTA of a parent patent can be eliminated by the application of ODP over an earlier-expiring child patent. Until then, applicants and practitioners need to be aware of the risk that the PTA of a parent patent can be eliminated by the application of ODP over an earlier-expiring child patent.