Atticus Finch a flawed character?

I am supposed to write a persuasive essay on Atticus Finch as a hero, or not. In my mind I believe that he is a hero, but I have to think of a counter-argument. I honestly cannot think of a flaw in Mr. Finch, (yes I have read the book.) My psycho English keeps saying that Atticus is a seriously flawed character, and I can't think of why. Any counter-argument ideas? Thanks!