Locke Lord QuickStudy: The Federal Circuit Explains Admissibility of Post-Priority Date Evidence Regarding Written Description and Enablement Proofs

In Amgen, defendants appealed the district court’s ruling that the patents-in-suit (i.e., U.S. Patent Nos. 8,829,165 and 8,859,741) were not invalid and granted a permanent injunction enjoining sales of defendants’ product, Praluent^®.  See id. at *1.  On appeal, defendants argued, inter alia, that the district court improperly excluded evidence regarding written description and enablement.  See id.

The patents-in-suit are directed to a genus of antibodies that bind to specific amino acid residues on PCSK9 and, thus, block PCSK9 from binding to LDL-Rs which results in reduced LDL-C levels in patients.  See id. at *1-*2.  At the district court, defendants argued, inter alia, that the asserted claims of the patents-in-suit were invalid for failing to satisfy the written description and enablement requirements, and sought to introduce evidence about antibodies, including defendants’ product, Praluent^®, that were developed after the undisputed priority date (January 9, 2008).  See id. at *3.  The district court excluded such post-priority date evidence after concluding that it lacked relevance because it did not “illuminate[] the state of the art at the time of filing” and, therefore, was not relevant “to determine whether there is sufficient disclosure of the claimed invention.  See id.  

The Federal Circuit disagreed, and concluded that the district court erred in excluding such post-priority date evidence because defendants’ evidence was not presented to show the state of the art as of the priority date, but rather to show that the patents’ specification did not disclose a representative number of species to support the genus claims.  See id. at *3-*4.  The Federal Circuit explained the “common sense logic of admissibility”:

As a logical matter, such evidence is relevant to the representativeness question.  Simply, post-priority date evidence of a particular species can reasonably bear on whether a patent fails to disclose a representative number of species falling within the scope of the genus or structural features common to the members of the genus so that one of skill in the art can visualize or recognize the members of the genus.

Id. at *4; see also id. at *5.  For much the same reasons, the Amgen court also held that the district court improperly excluded the post-priority date evidence for purposes of defendants’ enablement argument.  See id.  On enablement, defendants sought to introduce post-priority date evidence showing that plaintiffs “engaged in lengthy and potentially undue experimentation to enable the full scope of the claims.”  Id. at *5.  The Federal Circuit held that such post-priority date evidence would be relevant to determining if the claims were enabled as of the priority date and should not have been excluded simply because the evidence post-dated the priority date.  Id.  Based on the foregoing, the Federal Circuit reversed the district’s decision and remanded for a new trial on written description and enablement to include consideration of post-priority date evidence.  See id.

Accordingly, under Amgen, post-priority date evidence regarding written description and enablement should not be quickly discarded simply because it post-dates the priority date of the patents-in-suit.  Evidence not showing the state of the art at the time but instead probative of whether or not the specification adequately described or enabled the full scope of the invention can be considered as proof regarding these issues.  Litigants should consider all pre- and post-priority date evidence, including post-priority date experimental evidence, in proving whether the written description and enablement requirements of 35 U.S.C. § 112 are satisfied.