The Federal Circuit has upheld the Patent Trial and Appeal Board’s (PTAB’s) ruling that tribal sovereign immunity does not apply to inter partes review (IPR), dealing another blow to the Saint Regis Mohawk Tribe’s controversial patent-shielding deal with Allergan. Under that agreement, the Native American tribe had acquired the patents covering Allergan’s flagship dry-eye treatment, Restasis, and licensed them back to the company, hoping to use its tribal sovereign immunity to block IPRs against the patents. However, in February, the PTAB declined to dismiss the IPRs, holding that tribal sovereign immunity is not coextensive with the immunity held by the states and that the Tribe’s cited case law failed to establish that Supreme Court precedent on state immunity applied in the tribal context, among other arguments. The Federal Circuit declined to address the overlap of state and tribal sovereignty in its ruling on appeal, focusing more on how IPR was similar to other agency proceedings that the Supreme Court has previously held are not barred by sovereign immunity.