The lawsuit accuses Enviro Safe Air, of North Sioux City, S.D., of negligence and breach of contract for allowing workers to use open flame torches to remove asbestos during a renovation project.
Charles Miller, attorney for Enviro Safe Air, said he had not seen the lawsuit, which was filed Friday, and could not comment on it. He said both sides had been holding talks toward a settlement.
The November 2001 fire caused extensive fire, smoke and water damage to the Old Capitol, built in 1840. The building served as the territorial capitol and sits at the heart of the campus.
The building's signature golden dome, bell tower and cupola have since been replaced. Restoration continues inside the building, which suffered water damage from firefighting efforts.