Atticus follows the law very closely. He believes people have to take responsibility for their actions and admit the truth. His outlook is steadfast, something he makes very apparent after Bob Ewell's death. Atticus is under the impression that Jem was responsible, and although he was wrong.... he expected Jem to face up to his actions.
Heck Tate looked beyond the law and considered all the complications and circumstances.
By the end of their discussion, we see their opinions are very alike, as they both wish to leave Boo alone.