In the novel Tom Robinson is being persecuted for the rape of a white woman, which he never committed.
He is purely being prosecuted for being black but when Atticus who is a white lawyer is defending him in court he becomes somewhat outlawed in the white community.
Through this Harper Lee ties in the theme of natural justice and the reader understands Tates reason for doing this.
Harper Lee displays Scout learning the principal of mockingbirds towards the end of the novel when she compares sending Boo to court as bring sort of like shootin a mockingbird.
Harper Lee firstly introduces the principal of mockingbirds through Atticus when he says, Shoot all the bluejays you want, if you can hitem, but remember its a sin to kill a mockingbird.
The metaphorical meaning at first is ambiguous to Scout and the reader.Also the noun slaughter makes the murdering of Tom sound more brutal whilst the adjective senseless emphasises the fact the killing was unnecessary and perhaps done through hatred.Harper Lee uses description of characters to indicate who the mockingbirds of the novel are.Arthur (Boo) Radley is described to have feathered hair which shows the reader that not only is he innocent but he resembles the features of a bird.This only strengthens the themes of the mockingbird and innocence and how they coincide.Mr Heck Tate realises that Boo is a mockingbird as he wants to protect him after Bob Ewells death.Mr Tate understands the principal of mockingbirds and demonstrates this when he says, To my way of thinkin, Mr Finch, taking one man whos done you and this town a great service an draggin him with his shy ways into the limelight- to me thats a sin it shows that he is prepared to forget about the crime Boo had committed as he knows that Boo had good intentions and is innocent.Furthermore, Harper Lee constantly reminds the readers of the theme of mockingbird by her use of the extended metaphor.After the demise of Tom Robinson, Mr Underwood goes on to describe the death as the senseless slaughter of songbirds by hunters and children This phrase portrays Tom Robinson as a vulnerable songbird which persuades the reader to think that the killing of Tom Robinson was sinful.Moreover it relates back to the theme which amplifies the unfairness of the killing even further.Within this description of Toms death Harper Lee uses the technique of sibilance to enhance the harshness of Tom Robinsons death.