…Much of the new United States-Mexico-Canada Agreement simply updates the 25-year-old North American Free Trade Agreement, with new laws on intellectual property protection, the internet, investment, state-owned enterprises and currency. But the 2,082-page pact also includes significant changes in several key areas, including incentives to make cars in North America and open Canadian markets for American dairy farmers. It rolls back a special system of arbitration for corporations that has drawn bipartisan condemnation, and includes additional provisions designed to help identify and prevent labor violations, particularly in Mexico. …In a major change, the U.S.M.C.A. rolls back a special system of arbitration that allowed companies to sue governments for unfair treatment. …The Trump administration ultimately gave up on an effort to eliminate the so-called Chapter 19 provision, which gives the three countries a neutral way to challenge one another’s tariffs and other actions.