(Reuters) - A Native American tribe holding patents for drugmaker Allergan Plc AGN.N on Friday moved to dismiss a case brought by generic drug company Mylan NV MYL.O challenging the patents.

The Allergan logo is seen in this photo illustration in Singapore November 23, 2015. REUTERS/Thomas White

In a filing to the U.S. Patent Trial and Appeal Board, the Saint Regis Mohawk Tribe asked that Mylan’s case seeking to invalidate Allergan’s patents on dry-eye medicine Restasis be thrown out on the grounds that the board has no jurisdiction over the tribe.

The move was expected after Allergan announced on Sept. 8 that it had transferred Restasis patents to the tribe in order to protect them from administrative challenges.

Mylan in late 2016 asked the patent board to invalidate Allergan’s Restasis patents so it could launch its own generic version of the medicine, which generated $1.5 billion in revenue for Allergan last year.

A lawyer for Mylan said at a Sept. 11 court hearing that the company would vigorously oppose Allergan’s efforts, calling the deal with the tribe a “sham transaction.”

In its court filing on Friday, the tribe said it is sovereign government that cannot face litigation in an administrative court unless it expressly waives its immunity or the U.S. Congress abrogates immunity.

“Neither of these exceptions apply here,” the tribe said.

The tribe will receive a one-time payment of $13.75 million and annual royalties of around $15 million under the arrangement, Allergan said.

Allergan has come under fire over the deal, with U.S. Senator Sherrod Brown criticizing the drug company for exploiting a loophole to keep its prices high.

The company has said the transfer is only intended to shield the patents from review at the patent board, which it has called a flawed forum for patent disputes. Allergan has said it will not invoke tribal immunity in federal courts.