By: Johannes K. Buhl and Trey Powers, Ph.D.

As PTAB practitioners know, statistics on successful motions to amend are quite dismal[1]. But in a recent case, the PTAB shed light on what may be a successful strategy for patent owners to amend their claims in an Inter Partes Review.

In Lectrosonics v. Zaxcom, the PTAB found all of the claims of the challenged patent invalid as anticipated or obvious over prior art, but granted the patent owner’s Contingent Motion to Amend. The PTAB found that the proposed amended claims had a sufficient nexus to Zaxcom’s objective indicia of non-obviousness, and were therefore patentable.

Following an infringement suit, Lectrosonics sought an IPR, which the PTAB instituted. The challenged claims recited systems and methods for “combining” locally recorded audio data with remotely recorded audio data using a wearable device. In its case-in-chief, Zaxcom proffered evidence of objective indicia of non-obviousness including industry praise, long felt need, and failure of others. However, the PTAB did not find this evidence sufficient because, the PTAB found that the proffered evidence related to the elimination of “dropouts,” which are caused by, e.g. a loss of audio data when a recording source moves out of wireless range. In contrast, the challenged claims were broader, encompassing situations where audio data is merely “combined,” without necessarily having any tie to a drop out event.

Before considering the patentability of the substitute claims, the Board determined that Zaxcom had met the statutory and regulatory requirements for the motion to amend, first set forth in a precedential case involving the same parties in march 2019. The board found that Zaxcom met the requirements as they: (1) proposed a reasonable number of substitute claims, (2) showed that the proposed substitute claims respond to a ground of unpatentability involved in the trial, and (3) these substitute claims did not enlarge the scope of the claims or introduce new subject matter.

Subsequently, the PTAB held that Zaxcom’s amended claims, as a matter of fact, did have a sufficient nexus to the praise its commercial embodiment received. The amended claims specifically recited “replacing” audio data with locally recorded audio data. According to the PTAB, Zaxcom received industry praise for the “replacing” feature. Indeed, Zaxcom showed that its inventors received a technical Emmy award from the National Academy of Television Arts and Sciences for its commercial product. The Emmy related to the product’s ability to eliminate “dropouts” by “replacing” audio data and thereby dramatically simplify the recording process. And both parties’ experts agreed that the industry praise related to the elimination of “dropouts” afforded by the invention.


This case provides a strategy for patent owners seeking a motion to amend. By tailoring substitute claims so they have a sufficient nexus to objective indicia, patent owners may increase their chances of prevailing. Accordingly, patent owners should consider not just the prior art in preparing substitute claims. They should also determine whether they can craft valuable substitute claims with a nexus to any potential objective indicia of non-obviousness.

[1]Patent Trial and Appeal Board Motion to Amend Study, Installment 4: Update through March 31, 2018, page 7, found at: