This is specific to your particular edition of the book.
Judge Taylor assigns Atticus to defend Tom Robinson.
Judge Taylor because he knows that Atticus has the best chance of defending Tom Robinson
Judge Taylor specifically assigned Tom Robinson's case to Atticus Finch because he knew that Atticus was a fair and just lawyer who would provide an ethical defense for Tom. Additionally, Judge Taylor understood that Atticus was willing to take on such a controversial case without letting personal biases interfere with his representation.
Judge Taylor chose Atticus to defend Tom Robinson because he knew Atticus was a fair and respected lawyer in the community. Despite the racial tensions in Maycomb, Judge Taylor believed that Atticus would provide a competent and ethical defense for Tom.
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.
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.
Atticus had to take the case because Judge Taylor assigned it to him.
Judge Taylor visited Atticus Finch at home to inform him that he had been assigned to defend Tom Robinson, a black man accused of raping a white woman. The judge chose Atticus for the case because he believed him to be a fair and principled lawyer who would provide a vigorous defense for Tom.
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.
He is assigned the case from Judge Taylor.
Judge Taylor tries to help Tom Robinson by assigning Atticus Finch to his case because he knows Atticus will do his best to defend him and is not racist towards African- Americans, unlike the other lawyers and characters in the book.
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.