left arm (while Bob Ewell is a left-handed man). 

Ch. 18 begins with Mayella being questioned at court. Her accusation that Tom Robinson raped her is the reason that Tom Robinson is being prosecuted. She claims that she invited Tom Robinson to come inside and "bust up [a] chiffarobe for [her]" (ch. 18). (A chiffarobe is a piece of furniture that generally has drawers and a section to hang clothing.) She claims that he came into the house and took advantage of her, while she was attempting to get him a nickel. When Atticus gets to question Mayella, he asks questions about how Tom Robinson took advantage of her. He asks,

Do you remember him beating you about the face . . . You seem sure enough that he choked you. . . . You "kicked and hollered as loud as you could." Do you remember him beating you about the face? (ch. 18)

At this point, Mayella is quiet. She does not want to say anything that might reveal that she is lying. He asks her once more if she remembers being beat in the face. This time, she responds:

No, I don't recollect if he hit me. I mean, yes I do, he hit me. (ch. 18)

At this point, the inconsistency of her story is very apparent to readers. Did he hit her? Did he not hit her? Why does she keep changing her mind? Atticus then asks Mayella to "identify the man who raped [her]," and she asserts, again, that it was Tom Robinson (248). Atticus asks him to stand up. The book describes his appearance:

Tom Robinson's powerful shoulders rippled under his thin shirt. He rose to his feet and stood with his right hand on the back of his chair. . . . His left arm was fully twelve inches shorter than his right and hung dead at his side. It ended in a small shriveled hand, and from as far away as the balcony I could see that it was of no use to him. (ch. 18)

Tom has a crippled arm. Though he is strong, as seen by his "powerful shoulders," it would be nearly impossible for him to choke and beat someone about the face at the same time. Atticus points this out to the audience when he questions:

Miss Mayella, you've testified that the defendant choked and beat you –– you didn't say that he sneaked up behind you and knocked you cold, but you turned around and there he was –– . . . do you wish to reconsider any of your testimony? (ch. 18)

Nonetheless, she holds firm to her story, even though there is visible evidence that it would be practically impossible for him to abuse her in the ways she described. As Atticus continues to question her about the specific events, such as why her siblings did not respond when she was supposedly screaming for help, she stops responding to his questions. For several minutes her response repeats: "No answer" (ch. 18). She stops responding because she sees that Atticus has reason to doubt her story. She does not want to give him any more evidence against her. Nonetheless, Atticus does not give up. She eventually grows frustrated with his questions and shouts, once again, that Tom Robinson abused her:

I got somethin' to say an' then I ain't gonna say no more. [Tom Robinson] yonder took advantage of me an' if you fine fancy gentleman don't wanta do nothin; about it then you're all yellow stinkin' cowards . . . . (ch. 18)

Here, rather than offering additional evidence of the crime, Mayella turns to emotion as a tool of persuasion. She calls anyone who opposes her story a "coward," hoping that this will persuade her jurors toward her side of the case. When she stops providing solid evidence and begins to employ emotion, rather than logic, her argument loses even more credibility.

At his trial, Tom Robinson inadvertently makes the mistake of telling the truth and being honest, which the racist people in the community take as insulting.

Atticus has done an excellent job of showing everyone that Tom really is innocent. He would’ve been incapable of raping and beating Mayella. Because he only has the use of one arm, it is physically impossible for him to have held her down and beat her, as she claimed. In addition, the placement of Mayella’s bruises indicates that Tom could not be her attacker. Since he does not have the use of his left arm, and Mayella’s bruises on the right side of her face have been placed there by a left-handed person, in a perfect world, Tom should be exonerated.

However, Mr. Gilmer is not ready to give up. He condescendingly says that Tom was generous to help Mayella with her chores when he had his own chores at home to do. Tom responds that he did both sets of chores, to which Mr. Gilmer questions:

“You’re a mighty good fellow, it seems—did all this for not one penny?”
“Yes, suh. I felt right sorry for her, she seemed to try more’n the rest of ‘em—”
“You felt sorry for her, you felt sorry for her?” Mr. Gilmer seemed ready to rise to the ceiling.
The witness realized his mistake and shifted uncomfortably in the chair. But the damage was done.

Although he is truthful in his testimony, Tom makes a mistake that contributes to his wrongful conviction. Mr. Gilmer and many of the townspeople take offense at Tom’s words of expressing sorrow for Mayella. The townspeople’s racist views cause them to believe that Black people are not on the same level as white people; therefore, they take offense at a Black man feeling bad for a white woman. They believe that he has no right to feel sorry for her and they take his words as an insult. Even though the Ewells have no standing in the community, they are white, and racist people will still place them above Black people. Therefore, even though he is clearly innocent, Tom has no chance at coming back from his comment.

In the chapters relaying the trial scenes of Harper Lee's To Kill a Mockingbird, Atticus's cross-examination of the witnesses reveals several points of circumstantial evidence that point to Tom Robinson's innocence, not his guilt.

The first piece of crucial evidence is revealed during Sheriff Heck Tate's testimony, who confirms that Mayella Ewell had been bruised on the right side of her face. This proves to be a crucial point because Mayella also testifies that she had been attacked from the front, which means that only a man who could use his left hand could have hit her on the right side of her face while facing her. Heck Tate's second point of crucial evidence is that Mayella had been strangled by a man gripping her neck with both hands, which was evident due to the fact that she had bruises all around her neck. Again, only a man capable of using both hands could have bruised her entire neck.

Atticus's cross-examination of Bob Ewell, Mayella's father, is even more revealing. While on the witness stand, Atticus asks Ewell if he is literate, and when Ewell answers in the affirmative, Atticus asks him to write his name. Interestingly, Ewell writes before the court using his left hand. When asked by Judge Taylor if he is ambidextrous, Ewell responds with the very intelligent answer, "I most positively am not, I can use one hand good as the other. One hand good as the other," which shows that Ewell was very capable of having bruised Mayella on the right side of her face and of having strangled her with both hands (Ch. 17).

The most irrefutable evidence is revealed during Mayella's cross-examination. At one point, Atticus asks Mayella to point out the man in the courtroom she is charging with having attacked her. Mayella points to Tom Robinson, and Atticus has Robinson stand before the court. As he stands, he reveals that, as Jem points out, "he's crippled!" (Ch. 18). Scout further describes in her narration that Robinson's left arm was a whole foot shorter than his right and "hung dead at his side" (Ch. 18). His left hand was also shriveled and appeared to be completely useless. In fact, his left arm and hand are so useless, Robinson finds it impossible to keep his left hand on the Bible long enough for him to be sworn into the witness stand. Reverend Sykes explains to the children that Robinson had caught his left arm in Dolphus Raymond's cotton gin when he was a boy and nearly "bled to death" (Ch. 18). Robinson's physical status serves as undeniable proof it would have been impossible for him to have bruised Mayella on the right side of her face or to strangle her, which makes him look completely innocent of all he is being accused of.

In To Kill a Mockingbird, Tom Robinson is not guilty of anything. He is accused, by Bob and Mayella Ewell, of raping Mayella. But it seems abundantly clear that Mayella and Bob are lying and that Tom is completely innocent of any crime. When Atticus questions Bob Ewell on the stand, he makes it clear to note that Mayella had a wound on her right eye and had wounds all around her neck. Therefore, it would be more likely that someone with two good working hands who is also left-handed was likely to be the attacker. Bob Ewell is left-handed with two good working hands. Tom has only one good working hand, his right, and his left hand is basically useless due to an accident with a cotton gin. Given the testimony and this evidence and the fact that it was well known that Bob beat his children, including Mayella, it is fairly clear that Bob was probably Mayella's attacker and that she conspired with Bob to blame Tom for everything, knowing that a black man in 1930s Maycomb was likely to get convicted in spite of any evidence that might suggest his innocence. 

Tom gives his side of the story. He notes that he was trying to help Mayella because he felt sorry for her. The all white jury, with their racist conditioning, could not believe or accept that a black man could or should feel sorry for a white girl. Tom added that Mayella tried to kiss him. When he resisted, Bob Ewell happened to walk in and threatened Mayella, calling her a whore. In the end, the jury had Atticus' compelling logic (which pointed to Bob as the attacker) and beyond that it was Tom's word against Mayella's and Bob's. The jury let themselves be blinded by their prejudices and convicted Tom. 

Discussing the guilty verdict, Atticus tries to explain to Jem why the jury convicted an innocent man: 

“If you had been on that jury, son, and eleven other boys like you, Tom would be a free man,” said Atticus. “So far nothing in your life has interfered with your reasoning process. Those are twelve reasonable men in everyday life, Tom’s jury, but you saw something come between them and reason. You saw the same thing that night in front of the jail. When that crew went away, they didn’t go as reasonable men, they went because we were there. There’s something in our world that makes men lose their heads—they couldn’t be fair if they tried. In our courts, when it’s a white man’s word against a black man’s, the white man always wins. They’re ugly, but those are the facts of life.” 

In To Kill a Mockingbird, Tom Robinson had to take the stand. He had to explain what happened on November twenty-first. Although Tom Robinson was innocent of harming Mayella in any way, he made himself  look bad when he exclaimed that he felt sorry for Mayella. In the 1930s, in Maycombe, black men could not have any associations with a white woman. The fact that Tom Robinson admitted that he helped Mayella from time to time caused the jury to be suspicious of Tom's willingness to help a white woman.

During his testimony, Tom Robinson made it clear that he only helped Mayella because she seemed to have no one else to help her. The fact that Tom felt sorry for a white woman was more than the town of Maycombe wanted to hear. Black men had no rights. They were considered lesser people because they were black.

During his testimony, Tom Robinson told an all white jury that Mayella made advances toward him. This is hard for white people to hear. Although Tom Robinson was telling the truth, the all white jury did not want to believe him.

Tom Robinson described how Mayella tried to hug him and kiss him:   

The witness swallowed hard. "She reached up an' kissed me 'side of th' face. She says she never kissed a grown man before an' she might as well kiss a nigger. She says what her papa do to her don't count. She says, 'Kiss me back, nigger.' I say Miss Mayella lemme outa here an' tried to run but she got her back to the door an' I’da had to push her. I didn't wanta harm her, Mr. Finch, an' I say lemme pass, but just when I say it Mr. Ewell yonder hollered through th' window."

Clearly, Tom is trying to tell the truth. Sadly enough, he lived in a time when the truth did not count if it was coming from a black man.Tom's testimony is honest and sincere. Still, he was found guilty of raping Mayella, a crime he did not commit. 

Jem feels that Tom Robinson is innocent. Throughout the trial, Jem is rooting for Tom Robinson, and when Bob Ewell proves that he is left-handed, Jem says, "We've got him." (Lee 238) Following Atticus' closing speech, Jem approaches his father and says, "We've won, haven't we?" Before the verdict is read, Jem tells Reverend Sykes that there is no way Tom will lose this case based off the evidence. It is clear to Jem that Tom is innocent. Mayella and Bob's testimonies conflict, Bob Ewell was left-handed and probably beat his daughter, and Tom's handicap would make it impossible for him to have strangled Mayella. Jem has not yet experienced racial injustice at this level and is naive to think that an all white jury will take a black man's word over a white women's word. When the verdict is read, Jem is heartbroken when he hears that Tom Robinson is "guilty." Jem cries and repeats the phrase, "It ain't right." (Lee 284) Later in the novel, Jem tells Atticus they should do away with juries because they convicted an innocent man.

In Chapter 19, Tom Robinson gives his testimony during his trial in which he stands accused of raping Mayella Ewell. Atticus questions Tom Robinson first regarding the events that happened on November 21st. Tom Robinson denies allegations of rape, and his story drastically contrasts with Mayella’s. Mr. Gilmer questions Tom Robinson as to why he volunteered to help Mayella with various chores. Tom Robinson repeatedly tells Mr. Gilmer that he felt that Mayella needed help and it seemed like nobody ever helped her out. Mr. Gilmer calls Tom a mighty generous man because he helped Mayella out frequently without asking for monetary compensation. Tom responds by saying,

"Yes, suh. I felt right sorry for her, she seemed to try more’n the rest of ‘em—" (19.264)

Scout says that nobody in the courtroom was pleased with Tom’s answer. He made the mistake of saying he felt bad for a white person. During that time period in Maycomb, Alabama, African Americans were considered the lowest members of society. For a black man to feel sorry for a white person was unheard of. Even though the Ewells were considered dirty and trashy, they were still superior to any African Americans. What Tom Robinson said was considered an insult to white people. The fact that an inferior black individual would take pity on a white person was considered an offense.

In Chapter 19, Tom Robinson takes the witness stand and describes his background and interactions with Mayella Ewell. Atticus begins by questioning Tom as to why he was convicted of disorderly conduct. Tom explains that he got into a fight with a man and went to jail because he couldn't pay the fine. Then, Atticus asks Tom if he's ever spoken to Mayella before, and Tom admits that he has. He explains that Mayella asked him to help her with many chores and that he frequently offered his assistance when she asked. Tom tells Atticus that he was never paid for his services and refused to take a nickel from her. Later on, Mr. Gilmer cross-examines Tom and asks him why he went out of his way to help Mayella without excepting any type of payment. Tom says, "I felt right sorry for her, she seemed to try more'n the rest of 'em---" (Lee 264) Scout mentions that "the damage was done" and that nobody liked Tom's answer. In 1930s Alabama, a black man feeling sorry for a white person was unthinkable. Tom's answer was taboo, and the jury viewed him with contempt because of it. By telling the prosecutor he felt bad for Mayella, Tom hurt his chances of being acquitted and was eventually found guilty.

The main facts that prove that Tom Robinson has been falsely accused in To Kill a Mockingbird are that Bob Ewell did not call a doctor for Mayella and there is no proof the crime was committed, Bob Ewell is left handed, and Tom Robinson’s left hand is crippled.

First of all, Atticus goes to great pains to establish the inconsistencies in both Mayella and Bob Ewell’s stories.  Clearly they are both lying.  First of all, Ewell says he saw Tom Robinson rape his daughter, but he never called a doctor.  No one did.

"Well I can tell you why I didn't. It wasn't necessary, Mr. Finch.  She was mighty banged up. Something sho' happened, it was obvious." (ch 17)

If Mayella had really been attacked by someone other than her father, her father should have called a doctor.  He didn’t call a doctor because he didn’t want too many people asking questions.  A doctor would have revealed that Mayella had not been raped.

Second, Atticus also demonstrates that Mayella was beaten up on the right side of her face, and Bob Ewell is right handed.  Heck Tate testifies that the right side of Mayella’s face was beaten.

"'Mr. Finch. I remember now she was bunged up on [the right] side of the face.'" (ch 17)

For a person to be hit on the right side of the face, the person who attacked must be left handed.

If her right eye was blacked and she was beaten mostly on the right side of the face, it would tend to show that a left-handed person did it. (ch 17)

This is important forensic evidence.  Jem is quite convinced that there is no way that Tom Robinson can be convicted, since Bob Ewell is left-handed.

Finally, Tom Robinson’s left hand is crippled, so he could not have attacked Mayella on the right side of her face.

His left arm was fully twelve inches shorter than his right, and hung dead at his side. It ended in a small shriveled hand, and from as far away as the balcony I could see that it was no use to him. (ch 18)

In the end, it does not matter that there was no proof that the crime Tom Robinson is accused of was ever committed, that Bob Ewell beat his daughter, or that Tom Robinson is crippled.  Robinson is convicted because he is a black man accused by a white woman.

In chapter 14, Scout asks her father what rape is: "He sighed, and said rape was the carnal knowledge of a female by force and without consent" (135). She asks this because in chapter 12, when she goes to Calpurnia's church, she had asked Cal what Tom Robinson was in jail for. When Calpurnia told her it was for rape, she told Scout to get the definition from her father. The court case is detailed in chapters 17-20. Bob and Mayella Ewell claim that while Tom Robinson was helping Mayella with some chores one day, he violently raped her. There are no other eye witnesses to vouch for what they say, though. There is also no solid evidence to support their claims--not even a doctor's examination to draw evidence from because Ewell didn't think it was necessary. He didn't think it was necessary because the rape charge is clearly fiction. Unfortunately, in Maycomb, Alabama in the 1930s, a criminal charge by a white man against a black one winds up in court, gets tried without evidence or witnesses, and Tom is convicted of rape as charged.