A U.S. appeals court halted a review of Allergan PLC's patents covering Restasis, an eye treatment that generates more than $1 billion in annual reviews, Reuters reported.

The U.S. Court of Appeals for the Federal Circuit wants to decide on the jurisdictional issues raised by the drugmaker's intellectual property deal with the St. Regis Mohawk Tribe before it can allow the review to continue.

Under the deal, Dublin-based Allergan had transferred six of its Restasis patents to the Native American tribe to fend off legal challenges from makers of generic drugs.

The company licensed the drug back from the tribe whose patents could no longer be challenged due to sovereign immunity, a legal principle that grants Native American tribes immunity from civil suit.

However, the U.S. Patent Trial and Appeal Board ruled in February 2018 that generic-drug maker Mylan NV's legal challenge to Restasis patents could still go on without the tribe.