Next week, the U.S. International Trade Commission will hear arguments concerning whether the importation of Bombardier C Series jetliners into the U.S. could cause material damage to American companies. If the commission rules early in 2018 that the answer is “yes,” then duties already calculated by the Commerce Department will quadruple the cost of every C Series aircraft sold within U.S. borders. Such a ruling would effectively preclude C Series sales to U.S. carriers, and ...