You've learned to always keep your cool under fire and to get the verdict you want. You have an advantage on saving throws against being intimidated, persuaded, deceived or charmed.
You've practiced the ways of turning a case on its head. During this crucial moment during a trial, it is up to you to get the verdict you want. For one turn all attack rolls you do have an advantage and you can take 3 turns worth of actions as you want but the moment you fail a roll your turn is over and you are stunned for 1 turn. You do not get stunned if all your rolls succeed. You can use this ability once per long rest.
A Lawyer should always be optimistic in the face of a trial. When in a corner during a trial, an Ace Attorney always makes the last-minute deduction to solve the case and win the trial. Three times per long rest, when your back in a corner you can use your amazing deduction skills do find another clue in a case, so you can add your investigation stat to any roll you make.