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  • Federal Circuit Affirms PTAB’s Treatment Of Priority-Date Claims

    On October 1, 2018, the Court of Appeals for the Federal Circuit (CAFC) issued an opinion affirming a decision by the Patent Trial and Appeal Board (PTAB) cancelling a patent in inter partes reexamination.  Natural Alternatives Int’l, Inc. v. Iancu, —F.3d— (Fed. Cir. Oct. 1, 2018).  The PTAB and the CAFC both rejected the patent-owner’s argument that the patent in question was entitled to claim priority to one of the owner’s earlier patent applications.

    A third party challenged Natural Alternative’s patent in an inter partes reexamination — a (no longer available) Patent Office proceeding that has since been replaced by inter partes reviews — on the basis of an allegedly defective priority-date claim.

    Patent applicants are permitted to claim the benefit in a later application of the filing date of an earlier application, as long as the later application is filed while the earlier is still pending.  An earlier application date protects the application from intervening prior art, but because a patent’s twenty-year term begins with the earliest claimed application date, claiming priority to an earlier application serves to shorten the term of the patent that ultimately issues.

    In this case, the patent owner had filed a chain of eight applications, each claiming priority to the filing date of the first application.  The patent in question issued from the eighth application.  But during the original prosecution, after filing the sixth application (and perhaps intending to obtain several patents with different priority dates, and therefore different expiration dates), the patent owner amended the fifth application to no longer claim priority to the first four applications. 

    When the patent in question issued from the eighth application, it claimed priority back to the first of the earlier applications.  During the reexamination, however, the patent challenger argued that the change made to the priority claim in the fifth application broke the chain of priority, leaving the patent with the date only of the fifth application and therefore exposing it to fatal prior art (that prior art being in fact the patent that issued from the patent owner’s own first application).  The patent owner, on the other hand, argued that the priority claim in the eighth application should be found to be intact because when the sixth application was filed, the fifth correctly claimed priority all the way back to the first application — it was only after the sixth case was filed that the fifth case was amended to drop the priority claim.

    The PTAB held, and the CAFC affirmed, that the patent challenger was correct:  once the patent owner amended the fifth application to delete its priority claim, the sixth application — which was co-pending only with the fifth application — could no longer claim priority to any application earlier than the fifth.  That is, the amendment broke the chain of priority claims, even though it took place after the sixth application had already been filed, claiming priority back to the first application.

    The decision illustrates how important a complete analysis of priority dates under the Patent Office’s highly technical standards can be.  The broken priority chain noted by the patent challenger, which would have been apparent only from close inspection of the file for the fifth application, was decisive on the issue of patentability.