Patentee Has Burden of Persuasion on Non-Enablement of an Asserted 102 Reference

October 15, 2015


In Edmund Optics, Inc. v. Semrock, Inc. the PTAB addressed whether a petitioner, who did not put on evidence or arguments showing that the prior art enables the claimed invention in its petition, may do so in its reply, if the patentee argues that the prior art is non-enabling in its response.  IPR 2014-00599, Paper No. 72 at 22-23.  In that case the PTAB instituted inter partes review of all claims requested by the Petitioner, claims 33-36, 39-41, 44, and 45 of U.S. Patent No. 7,119,960 C1 (“the ʼ960 Patent”).  Id. at 2.  Petitioner asserted that all of the claims would have been obvious over a treatise by “MacLeod,” and also that claim 33 is anticipated by Macleod.  Id. at 6.

The ʼ960 Patent is directed to apparatuses for making optical edge and laser-line filters, methods of making such filters, improved filters, and  uses of such filters.  Id. at 3.  Claim 33 is reproduced below:

  1. A multi-layer, thin film laser-line filter exhibiting a transmission of greater than 90%, a full-width at half-maximum passband of at least 0.0031λc, and a blocking of optical density greater than 5 for wavelengths from 1.01λc to 1.1λc and from 0.92λc to 0.99λc wherein λc is a wavelength in nm of a laser directed through the filter.

Id. at 6.

In its institution decision the Board construed “thin film, laser-line filter” to encompass both soft and hard coated filters.  Id. at 7 (citing Paper No. 9 at 7).  The Board maintained this position in its final decision.  Id. at 16.

The Patentee argued in its patent owner response that, although MacLeod discloses a design for a multi-layer, thin film laser-line filter, and illustrates data for such a filter that appears to match the parameters for the filter recited in claim 33, MacLeod does not enable such a filter.  The Patentee asserted that the data in MacLeod is based on ideal, theoretical conditions, rather than empirical tests of an actual filter.  Id. at 18-19.  The Patentee’s expert explained that an actual filter, as opposed to a hypothetical filter design, could not achieve “lossless” transmission, i.e., the transmission losses would be greater than 10%.  Id.  On the other hand, Petitioner’s expert asserted that the expected transmission loss for an actual filter would be less than 10%, and thus the design of MacLeod would still anticipate claim 33.  Id. at 19.  The Patentee also argued that the Petitioner was not entitled to introduce extrinsic evidence of enablement in its reply, because such evidence would constitute part of the Petitioner’s prima facie case, which must be presented in the initial petition.  Id. at 25.

The PTAB discussed whether there is a presumption of enablement for a non-patent publication, acknowledging a district court split on the issue and the lack of controlling precedent.  Id. at 20-22.  The Board did not decide the issue because, assuming there was a presumption, the Board found that the Patentee rebutted it.  Id. at 22.  However, the Board did hold that a patentee has the ultimate burden of persuasion to show non-enablement of a prior art reference, based on the Federal Circuit’s holding in Impax Labs, Inc. v. Aventis Pharma, Inc., 545 F.3d 1312 (Fed. Cir. 2008).  Id. at 28.  Since a patentee has the burden of persuasion on non-enablement of a prior art reference, the Board held that the Petitioner in this case did not have to present evidence of enablement of the asserted references in its initial petition.  Id. at 25.  The Board also cited Dynamic Drinkware, LLC v. National Graphics, Inc., where the Federal Circuit held that the petitioner did not have the burden of proving that an asserted reference was fully supported by its provisional application.  Id. at 25 (citing  –F.3d–, 2015 WL 5166366 at *5 (Fed. Cir. Sept. 4, 2015)).

Therefore, the Board considered all of the evidence and arguments on enablement presented by both parties, and found that McLeod would not have enabled the filter covered by challenged claim 33.  Id. at 33.  Noting that the Petitioner did not address the Wands factors, the Board cited Petitioner’s failure to provide any evidence showing how one of ordinary skill could make the claimed filter based on MacLeod and the absence of any actual working examples fitting the criteria of claim 33, despite the undisputed fact that such filters were generally well known and thus one would expect working examples of claim 33 to be available, in support of its finding that MacLeod failed to enable the filter of claim 33.  Id. at 30-33.

For its obviousness argument, in its reply the Petitioner presented the results of a computer filter design program, showing that substitution of the ZnS and Cryolite materials of the filter design of MacLeod with tantalam and silcon (mentioned elsewhere in MacLeod) produced a filter design with the parameters recited in claim 33.

The Board was not persuaded by this evidence.  First, the Board noted that the Petition did not admit any differences between MacLeod and the claimed invention, and failed to explain why it would have been obvious to modify MacLeod’s hypothetical filter design to achieve the claimed performance parameters.  Id. at 40.  Second, Petitioner’s computer design evidence came in its reply, which was improper because it could have (and should have) been submitted with the petition.  Id. at 41.  By presenting it first in the reply, the Petitioner effectively precluded the Patentee from responding.  Id. at 41-43.  Third, Petitioner’s computer design evidence was based on hindsight, because it was obtained by inputting the parameters of claim 33 into the software and working backward to generate the appropriate filter design.  Id. at 44.



Alton Hare


Mr. Hare is a patent attorney in the chemical, pharmaceutical, and biotechnology practice groups. He maintains an active prosecution and litigation practice.

Mr. Hare’s prior experience focused on Hatch Waxman litigation. Before that he assisted a solo patent attorney by drafting pharmaceutical formulations patents and office action responses. Mr. Hare also interned at the Federal Circuit for the honorable Chief Judge Rader.