Addressing for the first time which party bears the burden of
proof as to the accuracy of a petitioner's identification of
real parties-in-interest (RPIs) in an inter partes review
(IPR), the US Court of Appeals for the Federal Circuit found that
the petitioner bears the ultimate burden of persuasion. Worlds
Inc. v. Bungie, Inc., Case Nos. 17-1481, -1546, -1583 (Fed. Cir.
Sept. 2018) (Prost, CJ). In addition, the Court clarified that a
petitioner's identification of RPIs does not create a formal
presumption of accuracy. As a result, a petitioner must use
evidence to carry its burden, if and when a patent owner disputes
the identified RPIs.
In 2012, Worlds sued Activision Publishing in district court for
infringing various patents related to video gaming. Activision did
not file an IPR petition challenging the validity of any claims of
the asserted patents. In late 2014, Worlds added a new accused
product to the litigation—a product Activision distributed
for Bungie
