Because he feels that every lawyer has a case at one time in his life tht changes him, and this is his. He choses to defend him because he knows that no one would defend a black man, that he owes it to his race on apology for the unfairness that has been given to the black man from the dawning.
Atticus defends Tom because he can not defend himself and he knows he will not get a fair trial.
He feels he should answer to his kids honestly. When Jem and Scout find out that Atticus is defending Tom Robinson, he honestly tells them what happens
Mrs. Maudie explained that Judge Taylor assigned Atticus to defend Tom Robinson because he knew that Atticus would give Tom a fair trial and do his best to help him. Judge Taylor respected Atticus's integrity and believed he would give Tom the best chance at a fair trial, despite the racial prejudices in Maycomb.
Just about the time Scout decides that she prefers the company of men, Atticus interrupts the meeting with the news that Tom Robinson has been killed in an attempted escape. In the kitchen, Atticus asks Calpurnia to accompany him to give the news to Tom's wife, Helen.
Because Tom was black and Atticus was white, they expected Atticus to do a lackluster job, and not give it his full effort. On the contrary, Atticus fought the case to his fullest, going as far as to call Tom up to the witness stand. In doing so, everyone learned what had really happened, and yet they let Tom get punished for it anyway.
Miss Maudie pointed out that judge Taylor appointed Atticius to the case to help Tom Robinson. He rathered Atticus instead of the regular public defender.
She hears that Atticus has to defend other people but he also defends himself. People don't like this. This does not give her any comfort because it confuses her.
because that's not the right word to use to describe someone
Atticus believes in human rights. He believes everyone has a right to a fair trial and a competent defense. Atticus does not believe this should only apply to the white race. This is not to say that Atticus believes he has much hope in swaying the town or jury of Tom's innocence. Tom realizes that although he believes in equality in law, most do not. It is his integrity that pushes him to do this, even in the face of almost certain defeat. Atticus's defense of Tom makes Scout's life at school even more difficult. Her father has been on her about fighting with her fists, yet she is being taunted for his representation of Tom Robinson. It is a difficult concept for a child to grasp, and she is not immediately approving of her father's choice.
The judge appoints Atticus to the case as the defendant's pro bono (free) attorney because the judge realizes Atticus is the best lawyer in the county to give the man a truly active defense. Atticus takes the case because he believes that Tom Robinson is innocent and he would like to see justice done. He is unhappy with the way blacks are treated in general.
Scout promises Atticus that she will continue attending school, even though she does not want to go. This promise is made after Atticus encourages her to give school a chance and not to let her current frustrations with her teacher affect her attitude towards education.
They give Atticus gifts of food. Hope this helps!
Uncle Jack believes that Atticus doesn't want to teach the children to shoot because he wants to instill a sense of responsibility and respect for firearms. Atticus also values the importance of defending oneself only as a last resort and does not want the children to view shooting as a casual or violent activity.