If a Judge believes the amount of a damage award is either too high or too low, he can grant a new trial.  Or, he can tell the side which benefited that they can voluntarily agree to a reduction, (remittitur), or agree to an enhancement, (additur) instead of holding a new trial.  The parties are told what the new amount will be and they can agree, or not.  This is a fairly rare occurrence and the Judge will only do it, when it is apparent the jury was confused and plainly got the result wrong.