When Tom Brady's appeal hearing kicks off Tuesday, key arguments will be about who ordered his four-game suspension and whether science supports the league's findings about deflated footballs. The NFL says Commissioner Roger Goodell authorized the discipline that was imposed by league executive Troy Vincent, who signed the letters sent to Brady and the New England Patriots informing them of the penalties. The NFL Players Association challenged Vincent's power to issue punishment, citing Article 46 of the league's collective bargaining agreement. More...