(February 2, 2017, 9:24 AM EST) -- WASHINGTON, D.C. — A Montana insurer and the United States traded barbs over whether the Patient Protection and Affordable Care Act (ACA) risk-corridor program requires annual payments and if the failure to make them provides the basis for a suit in a pair of dueling motions seeking dismissal or summary judgment filed Jan. 10 and 17 (Montana Health Co-Op v. The United States, No. 16-1427C, Fed. Clms.)....