Explain why atticus takes tom robinson’s case

Atticus accepted Tom Robinson's case because he knew no one else would want to take the case, and if anyone else did, he wouldn't put on a good case or care whether Tom was convicted. Atticus knew the odds of getting Tom off from the very beginning, but he knew that he had to try.

- "the die is cast; i have consented to return if we are not destroyed. thus are my hopes blasted by cowardice and indecision; i come back ignorant and disappointed. it requires more philosophy than i possess to bear this injustice with patience. i have lost my hopes of utility and glory; i have lost my friend."