Why is Juliet's dishonesty unjustified in the play?

In order to argue that Juliet is unjustified in her deceit the audience must make a positive assessment of Lord Capulet's intentions, both toward his daughter and toward Romeo. In Act I Capulet comes across as a wise and benevolent father. In Scene 2 he appears to be a man that is totally interested in the happiness of his daughter. He initially claims that his daughter is too young to marry but when pressed by Count Paris he insists that the Count win Juliet's heart. He will not approve of any marriage unless his daughter is in approval as well. Likewise, in Scene 5 Capulet warns Tybalt against fighting Romeo and even suggests that Romeo is an honorable young man:


Content thee, gentle coz. Let him alone.He bears him like a portly gentleman,And, to say truth, Verona brags of himTo be a virtuous and well-governed youth.


If not for the outburst in Act III, Scene 5 in which he berates Juliet and threatens to disown her if she doesn't marry Paris it would be easy to come away with an affirmative reaction to Capulet. It's at least worth pondering whether the Capulet we meet in Act I would look favorably on the relationship between his daughter and the only son of his mortal enemy. Nevertheless, the ugliness in Act III cannot be overlooked. Obviously, Juliet knew her father well, and she understood that she could never reveal her true feelings to him about such a sensitive issue. Therefore, it must be concluded that Juliet is correct to lie to her parents about what was going on. In all likelihood Capulet would have forbidden her to see Romeo and the situation may have led to more violence between the families.