Uniloc USA owns US 5,490,216 (‘216), with claims directed to “[a] registration system for licensing execution of digital data in a use mode….”  Sega petitioned for Inter Partes Review of the ‘216 patent, arguing that Claims 1–20 are anticipated by US 5,509,070 (“Schull”), which was filed on 15 December 1992.  The ‘216 patent was filed on 21 September 1993, but claims priority to AU PL5524, filed on 26 October 1992.  In other words, Schull is only prior art if ‘216 does not get the benefit of the Australian filing date.  The PTAB concluded that the Australian application did not provide adequate written description support for the U.S. claims, and held that Schull anticipates ‘216 Claims 1–20.

At issue was the limitation “generating means” in the U.S. claims.  In a previous lawsuit between Uniloc and Microsoft, the Federal Circuit had construed “generating means” to mean “to generate a local or remote licensee unique ID/registration key,” and agreed with the district court that the corresponding structure was “a summation algorithm or a summer.”  The PTAB concluded that no such summation algorithm was present in the Australian application, and therefore the U.S. claims could not take the benefit of the Australian filing date.

Uniloc argued that this was legal error.  While a failure to describe adequate structure in the specification to support a §112(6) claim limitation can give rise to an indefiniteness failure under §112(2), the priority analysis has historically focused on whether the priority filing contains adequate written description to satisfy §112(1).  X2Y Attenuators, LLC v. Int’l Trade Comm’n, 757 F.3d 1358, 1365 (Fed. Cir. 2014).  Uniloc argued that questions of §112(2) and §112(6) are not germane to the priority analysis, and therefore the PTAB had made an error of law in addressing these considerations when deciding priority for the ‘216 patent.  The Federal Circuit Court of Appeals (CAFC) disagreed with Uniloc and affirmed the PTAB.

Although this decision is not precedential, the reasoning here could have important implications in many IPRs and PGRs in the future.  The extent of the prior art is determined in view of a patent’s priority date. If a patent is not entitled to the benefit of its priority filing, the world of prior art is correspondingly larger.  Moreover, the CAFC has recently made it easier for a claim limitation to be regarded as a means-plus-function (§112(6)) limitation.  Williamson v. Citrix Online, LLC, 792 F.3d 1339, 1349 (Fed. Cir. 2015) (en banc).  Therefore, a would-be challenger in IPR should pay careful attention to any limitations in the challenged patent that could be regarded as means-plus-function, and then scrutinize the priority filings to see whether the priority filings have adequate structure (and teachings listing the structure to the claimed function) to support the means-plus-function limitations in the patents to be challenged.  If the supporting structure is not clearly present in the priority filing, then the challenged patent can be attacked on a wider basis of prior art.