An Idaho man is suing police over claims that an officer threw him to the ground during St. Patrick's Day celebrations in Butte last year.

Shea Lamp claims the officer, Shawn Mayo, attacked him in an unprovoked assault.

The Montana Standard reports the lawsuit filed recently in Butte District Court alleges Lamp got into an argument with another man outside a bar on March 17, 2012.

Lamp says Mayo attacked him as he was walking away.

He says he received a broken nose, a broken eye socket and a compression fracture to the spine.

Lamp names Mayo, the Butte and Billings police departments, Butte-Silver Bow County and the city of Billings as defendants.

Butte County Attorney Eileen Joyce says an attorney with the county's insurer will handle the case.