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On August 28, 2023, the Court of Appeals for the Federal Circuit issued a decision in the case of In re: Cellect, LLC. Among other things, the Court determined that when a patent’s term is extended through Patent Term Adjustment (PTA), the expiration date after the PTA has been added should be used to determine if there is obviousness-type double patenting (ODP). This article addresses a few important considerations resulting from this decision, particularly in cases where a parent and child exist.

Effect of a Terminal Disclaimer on Patent Term

Under current law, if an application was filed on or after June 8, 1995, the patent will have a term of twenty years from the application’s effective filing date. However, this term can be shortened due to certain actions taken during prosecution. As a result, patents issued from both a parent and child may have the same expiration date unless adjustments are made by PTA or Patent Term Extensions (PTE).

Frequently when a child application is being prosecuted, an Examiner will request that a Terminal Disclaimer (TD) be filed in the child to prevent ODP. In other cases, during the prosecution of a parent application, an Examiner may request that a TD be filed in the parent to prevent ODP. Before determining whether a TD should be filed, it is important to determine the effect that the TD will have on the term of the patent. There are two rules to consider in making this determination:

  1. Filing a TD in a parent or child application will always result in that application having the shorter of the two patent terms, if there is any difference.
  2. Filing a TD in a parent or child application will never affect the term of the other (child or parent) application.

When ODP may potentially Exist

Anytime there are parent and child-issued patents, the patent with the longer term is in danger of potentially being invalid under ODP if the claims of the longer-term patent are not patentably distinct from the claims of the other patent.

One exception to this rule is the safe harbor provision provided by 35 USC § 121, which states that “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.” A proper divisional application must not only be the result of the restriction requirement, it must also have “consonance” with the restriction requirement. Consonance requires that the line of demarcation between the "independent and distinct inventions" that prompted the restriction requirement be maintained.

In other words, a divisional application filed as a result of (and maintaining consonance with) a restriction requirement in the parent cannot be invalidated or rejected over the parent under ODP. Similarly, if a divisional application is filed as a result of a restriction requirement in the parent, the parent cannot be invalidated or rejected over the divisional under ODP.

Use of a Terminal Disclaimer

To avoid ODP, a TD can be filed in the patent having the longer term to thus shorten the term to that of the other patent or patents in the family. If the patents expire at the same time, ODP cannot exist, provided that the patents are commonly owned. Where there is at least one common inventor, but the patents are not commonly owned, a TD will not avoid an ODP issue. 

A terminal disclaimer can be filed after the patent has been issued, but such a terminal disclaimer will not obviate an ODP issue if the reference patent has expired before the filing of the TD. Accordingly, a patent Applicant has the opportunity to file a prophylactic TD up until the time that the reference patent expires.

Accordingly, any time a child is about to issue, the family should be reviewed for potential ODP issues. Furthermore, in view of the recent In re: Cellect decision, patentees may wish to review every case where a patent family has patents that have already been issued and are currently unexpired to consider possible ODP issues. If there is a possibility of ODP, a TD can be filed in the patent or patents with the longer term to avoid ODP.