Affirmation or approval; adoption of an action that was done on oneÂ’s behalf and treating that action as if it had been authorized by that person before the fact of it having been done. By ratifying an act or action, a person becomes responsible for the consequences of that act or action. Ratification by a two-thirds vote of Congress is needed to propose a constitutional amendment, which must then be ratified by three fourths of the states for it to take effect.