This Note is composed of four parts. Part I reviews the origins, development, and purpose of both tribal and state sovereign immunity, compares the two doctrines, and concludes that the two are functionally the same despite deriving from different historical roots. Part II provides an overview of the history and purpose behind the patent system, the America Invents Act, and IPRs. Part II also analyzes the constitutionality of IPRs, as decided by the Supreme Court in Oil States Energy Services, LLC v. Greene’s Energy Group, LLC. Part III introduces and addresses the five IPR decisions on state sovereign immunity, Mylan I, and Mylan II. In addition, it discusses the PTAB’s internal inconsistency in applying state and tribal sovereign immunity and the inconsistency between the PTAB’s state sovereign immunity precedent and the Federal Circuit’s rationale and holding in Mylan II. Finally, Part IV of this Note argues that (1) the Federal Circuit’s Mylan II holding is correct; (2) policy implications dictate that sovereign immunity of either form should not apply in IPRs; and (3) if the Supreme Court grants ceriorari in LSI Corp., Mylan II’s holding, as well as the LSI Corp. holding should be read to prohibit both state and tribal immunity equally because of the similarity between the two doctrines.