Why is it important for the legislative branch to be able to override a president's veto?

The defendant is charged with the battery of a bouncer at a local tavern. at the trial, the prosecutor introduces evidence that while the bouncer was attempting to question the defendant about her intoxicated demeanor, the defendant committed a battery on the bouncer. the defendant attempts to defend against the charge on the basis of self-defense, insisting that the bouncer used excessive force in stopping her from entering the tavern. the defendant attempts to introduce into evidence an authenticated copy of the tavern records that show that three patrons had written complaints against the bouncer within the past six months for the use of excessive force. the prosecutor objects on the grounds that the records are inadmissible character evidence. should the court sustain the objection?